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CHANGES OF PHYSICOCHEMICAL AND SENSORY CHARACTERISTICS OF
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PACKED RIPE TABLE OLIVES FROM SPANISH CULTIVARS DURING SHELF LIFE
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Pedro García-García*, Antonio Higinio Sánchez-Gómez
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Fernández
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Department of Food Biotechnology, Instituto de la Grasa (AECSIC)
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Avda. Padre García Tejero 4, 41012 Sevilla (Spain)
and Antonio Garrido-
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Short title: Ripe olive shelf-life
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*Corresponding author:
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Pedro García-García
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Department of Food Biotechnology, Instituto de la Grasa (AECSIC)
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Avda. Padre García Tejero 4, 41012 Sevilla (Spain)
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Tlf: +34 954690850
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Fax: +34 954691262
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e-mail: pedrog@cica.es
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Summary
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Changes in the physicochemical and sensory characteristics of commercial plain
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(whole) and pitted ripe olives of the Gordal, Manzanilla, Hojiblanca and Cacereña
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cultivars were studied during a three-year period in conditions that mimic those found in
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real life during the storage of such products. No spoilage developed during this period.
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Throughout the shelf-life, a marked valley decrease in the pH of cover brine at the
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beginning of storage followed by a progressive decrease was observed, the surface
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colour (measured instrumentally) and firmness of the olives degraded in accordance
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with a first-order kinetic, iron and calcium addition reduced colour and firmness
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degradation respectively. Also, a slight browning of the cover brines at the beginning of
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the storage was observed. No significant changes in most of the sensory characteristics
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were observed by the panel test during shelf-life except for a limited change in olive
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surface colour. At the end of the shelf life, most of the samples were classified as “extra”
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category according to the IOC sensory evaluation method and only plain Gordal
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presentation was classified as “first, choice or select”.
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Key words: olives, sensory analysis, shelf-life
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Introduction
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Ripe olive processing was introduced in California (USA) at the beginning of the 20th
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century. Nowadays, this style is wide spread in all table olive producing countries.
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According to the latest data published by the International Olive Council (IOC), ripe
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olives may account for around 30% of the world’s table olive production, which was
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about 2,400,000 tons in the 2011/2012 season (IOC, 2013); this means that 630,000
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tons/year are prepared as ripe olives.
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The style is described as “olives darkened by oxidation” in the Trade Standard for
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Table Olives issued by the International Olive Council (IOC, 2004). However, they are
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commonly known by their original American name: ripe olives.
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Usually, fruits for producing this style are previously stored in an aqueous
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solution (brine or acidic water) and darkened throughout the year according to demand
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(de Castro et al 2007). The darkening process consists of successive treatments of the
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fruits with a dilute solution of NaOH (lye); during the intervals between lye treatments
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the fruits are suspended in water through which air is bubbled (Sánchez-Gómez et al
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2006). Throughout this operation the fruits darken progressively (Brenes et al 1992).
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The colour formed is not stable and fades progressively after oxidation. To prevent this
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deterioration, fruits are immersed in ferrous lactate or gluconate for several hours
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(García et al 2001). The product has a final pH above 4.6 and its preservation is only
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achieved by sterilization (CODEX/COI 1990). The most common commercial
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presentations in retail are whole and pitted olives.
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The UK Institute of Food Science and Technology (IFST) defined shelf-life as
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‘‘the period of time during which the food product will remain safe, retain its desired
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sensory, chemical and microbiological characteristics, and comply with any label
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declaration of nutrition data” (IFST 1993).
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According to the European Union Directive (2000) relating to the labelling,
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presentation and advertising of foodstuffs, "date of minimum durability of a foodstuffs is
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the date until which the food retains its specific properties when properly stored”.
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However, after that date, the food may still be in satisfactory condition and quality, with
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a high probability of retaining those circumstances for a further additional period of time.
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The shelf-life is different from the expiration date, which refers to food safety,
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while shelf-life has to do with quality of food. Basically, the appropriate shelf-life
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depends on the manufacturer who makes the product. To be confident of its statement,
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the company should have done the necessary work in order to determine the correct
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shelf-life.
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In Spanish style green olives, a first approach to the shelf-life was carried out by
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Sánchez et al (1997) but was limited to only Manzanilla cultivar packed under laboratory
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conditions stored at 20 ºC but, recently, a research with different cultivars and
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commercial preparations under real conditions of storage has been published
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(Sánchez-Gómez et al 2013). Additionally, the losses in fruit firmness and colour with
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time in untreated green olives of the Conservolea cultivar packed in vacuum or modified
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atmospheres were reported by Panagou (2004).
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In ripe olives, the evolution of parameters such as the pH of the cover brine,
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surface colour and fruit firmness of different cultivars (Hojiblanca, Manzanilla and
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Cacereña) has been monitored, using an accelerated shelf-life test (ASLT) (García-
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García et al 2008). However, changes in sensory characteristics were not monitored
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due the reduced time period of study and the strong effect of temperature (up 60 ºC) on
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these attributes.
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The aims of the present work were to study the evolution of the physico-chemical
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and sensory characteristics of commercial ripe olives of different Spanish cultivars
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(Gordal, Manzanilla, Hojiblanca and Cacereña), according to presentations (plain and
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pitted) and stored under real preservation conditions during the period of time (3 years)
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currently adopted for the "best before" recommendation on the label.
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Materials and Methods
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Olives and storage
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The study was carried out with fruits from the most common cultivars devoted to ripe
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olive trade preparations in Spain (Gordal, Manzanilla, Hojiblanca and Cacereña),
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presented as plain and pitted (Table 1). The olives were packed in tin cans and glass
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bottles (jars) with contents ranging from 150 g in “12oz cans” of pitted Manzanilla to
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1.800 g in “A10 cans” of whole Gordal.
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The experiment was initiated immediately after processing the olives (supplied by
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Spanish processors) and the sample collection was coordinated by INTERACEITUNA
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(Spanish Inter-professional Association of Table Olives).
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The samples were stored in the pilot plant of the Food Biotechnology Department
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of the Instituto de la Grasa (Sevilla, Spain). The storage temperature was periodically
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controlled, between 12:00 and 13:00 hours, at least every 10-14 days. The average
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temperature of storage was 22.7ºC, and ranged
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summer (Sánchez-Gómez et al 2013), with a maximum daily fluctuation of about 3 °C.
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Only, ¼ gallon containers (pitted Hojiblanca, pitted and whole Cacereña) were exposed
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to entering light through the windows of pilot plant. Therefore, the applied storage
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conditions properly mimic those found in real life during the storage of such products.
from 13 ºC in winter to 32 °C in
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Physicochemical analysis
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Samplings were made upon receiving the product (0 months) and at 2, 6, 9, 12, 18, 24,
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30 and 36 months of storage. At each sampling time, two samples (tin cans or glass
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bottles) for each of the commercial presentations were analyzed.
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In the case of jars, the presence of sediment at the bottom of the containers was
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observed before opening. Then, regardless of the type of container, vacuum or
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overpressure (mm of mercury) the interior of the containers was monitored by
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introducing a gauge through the lid of the can or jar.
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The determination of pH and NaCl concentration in the cover brines was carried
out using the routine methods described by Garrido Fernández et al (1997).
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The colour of the solutions was determined as the difference in absorbance at
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440 and 700 nm (A440–A700), using a 1-cm cell path length and a Varian Cary 1E
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Spectrophotometer (Malgrave, Vi, Australia). Previously, the liquids were centrifuged at
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12,000g for 10 min (Montaño et al 1988). The colour was also expressed in terms of the
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CIE
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(yellowness/blueness).
L*
(whiteness
or
brightness/darkness),
a*
(redness/greenness)
and
b*
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The surface colour of the fruits was measured using a BYK-Gadner Model 9000
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Colour view spectrophotometer (Silver Spring, MD, USA). Any interference from stray
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light was minimized by covering the samples with a box, which had a matt black interior.
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Colour was expressed as reflectance at 700 nm (R700) (Garrido Fernández et al 1997).
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Lower reflectance values indicate darker colours. In addition, colour was measured in
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terms of the CIE L* a* b* parameters and their derivates Chroma (C) and Hue angle (H).
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Results were the mean of 10 measurements.
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Firmness was measured using a Kramer shear compression cell coupled to an
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Instron Universal Testing Machine (Canton, MA, USA). The cross head speed was 200
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mm/min. The firmness of the olives, shear compression force in Newton (N), was
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expressed as N/100 g pitted olives and the value was the mean of 10 measurements,
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each of which was performed on one pitted olive for the Gordal cultivar and on three
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pitted olives for the other cultivars.
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Iron and calcium in the olive flesh was determined, in triplicate, by flame atomic
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absorption spectrometry in 3 samples of each commercial presentation (García et al
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2002).
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Sensory evaluation
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Canned fruits were evaluated by an 8-member trained panel, using the Department’s
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standardized testing room. Evaluations were made at product reception (0 months) and
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at 6, 12, 24 and 36 months of storage. This panel has a high level of training since it has
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been used for decades for different studies on various types of olives (Rejano et al
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1995; Medina et al 2011; Sánchez-Gómez et al 2013) and, particularly, for all the works
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related to the development of the sensory method issued by the International Olive
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Council (2010).
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The olives were tested according to the "Method for sensory analysis of table
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olives", COI/OT/MO 1/Rev.2 No 1 (IOC 2010), using the profile sheet also included in
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this methodology. This method employs the descriptors related to the perception of
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negative sensations (abnormal fermentation and other defects), gustatory attributes
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(salty, acid, bitter) and kinaesthetic sensations (hardness, fibrousnesses, crunchiness),
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in order to commercially classify the olives. When appropriate, specific descriptors were
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added to the sheet; these were related to external appearance: surface colour,
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brightness and skin defects; odour/flavour: typical flavour, soap taste (due to possible
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wrong neutralization) and metallic taste (due to iron addition); and texture: skin strength
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and pit release, using the same unstructured scale recommended in the IOC Standard
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(IOC 2010).
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Three or four olives were presented to each taster in a normalized glass
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according to standard COI/T.20/Doc. No 5 (Glass for oil tasting). Panellists should
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indicate the intensity they perceived for each of attributes in the scales of the provided
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profile sheet. The left extreme indicates the absence of an attribute while the right end
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was maximum perception.
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To determine the intensities of the attributes listed in the profile sheet the
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segment running from the origin of the scale to the mark made by the tester was
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measured using a ruler. The segment was expressed to one decimal place. The scale
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measured 10 cm long and the intensity ranged from 1 to 11. The statistic used to
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indicate the values of the attributes is the median of the individual data of the 8 testers
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(IOC 2010).
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Degradation kinetic
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For the degradation of surface colour and texture, kinetics of diverse orders was
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checked. Finally, a first-order kinetics was assumed. It was similar to that used by
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Sánchez-Gómez et al (2013) in Spanish green table olives and that applied to other
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parameters for ripe olives (García-García et al 2008). If the quality factor is designated
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as F, its rate of destruction over time (month) is given by the equation:
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dF/dt = - k * F
(1)
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where dF/dt = degradation of parameter per unit of time, F = value of parameter at time
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t, k = rate constant (month-1) which leads to the integrated equation:
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Ln (F/F0) = -k * t
(2)
where F0 represents the initial value of the studied parameter at time zero (month).
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Statistical analysis
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Statistica version 6.0 (StatSoft, Tulsa, USA) for windows was used for data analysis.
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Comparison of parameters among commercial presentations was carried out by
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superimposing their corresponding confidence intervals (CI) at p<0.05. Differences were
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considered significant when the CI did not overlap. ANOVA post comparisons were also
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made considering the same level of probability (p<0.05).
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Results and discussion
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Visual observation of jars and vacuum
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The jars of whole and pitted ripe olives did not present sediment at the bottom of
the containers or turbidity in cover brines after three years of conservation.
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During shelf-life, no significant variation in the determinations of vacuum in the
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olive containers was observed. As shown in Table 1, the highest vacuum values were
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observed in non-deformable containers such as jars (11.1-15.7 mm of mercury). In
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cans, the vacuum values were lower (3.2-8.3 mm of mercury), possibly because of the
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slight deformation produced when the can was pressed with the vacuum gauge as
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demonstrated by the fact that the lowest vacuum value (p<0.05) was shown in the
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largest can (A10 Gordal–Plain, Table 1), which deforms more easily. This also was
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observed in the shelf-life study of Spanish green table olives (Sánchez-Gómez et al
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2013).
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It is noteworthy that this vacuum retention means that the product was stable and
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no secondary fermentation was produced in the containers during shelf-life. Therefore,
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thermal sterilization treatments applied as well the closures of containers were always
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appropriate.
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pH changes in brines
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The initial pH values (6.4-7.2) of cover brines were normal for this type of
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preparation. However, contrary to what happens with green olives (Sánchez-Gómez et
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al 2013), pH did not remain stable over the shelf-life. As can be seen in Figure 1 there
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was always a rapid decrease in the initial levels followed by a subsequent increase after
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the 6th month of storage. However, after the 9th month a new gradual decrease was
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noticed up to the end of storage.
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Garcia-García et al (2008) observed that the pH of the ripe olive cover brine
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decreased with time according to a first-order kinetic, the rate was higher when the
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temperature increased. The absence of the initial decrease and subsequent increase
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shown in Figure 1 in the ASLT tests could have been due to the constant (although
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different) temperatures used for the storage in the ASLT experiments.
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On the contrary, in this study the storage temperature was not constant. During
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the first four months (March-June) the temperature increased up to 32°C, a level which
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was maintained until the 6th month sampling at the end of August. These high
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temperatures can produce, according to the study of Garcia-García et al (2008), a more
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rapid decrease in pH, which may explain the initial drop in pH observed in Figure 1.
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When trying to adjust the pH evolution to a 1st order kinetics as García-García et
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al (2008), the fit obtained was low (R2 <0.4) as expected from the evolution during the
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first few samplings (Figure 1). However, when removing the points corresponding to
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sampling at 2 and 6 months, the remaining points fit well (R2> 0.81) to a first-order
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kinetics, as shown in Table 2.
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Rate constant values (0.0015-0.0052 month-1) were of the same order as the
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average value (0.0033 month-1) for all commercial presentations at 20 °C obtained by
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Garcia-García et al (2008).
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The most influential factor on the pH change rate was the commercial
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preparation. Thus, for the same cultivar, the rate was statistically higher (p<0.05) in
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plain olives than in pitted olives (Table 2). This may be because during sterilization the
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pulp-liquid exchanges are favoured in the pitted olives. The cultivar had no effect on the
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rate constant. This decrease in pH over time had no meaning from the safety point of
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view because ripe olives are preserved by heat treatment and are then a sterile product.
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Cover brine colour
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As shown in Figure 2, the evolution of (A440-A700) parameter, brine colour, with time was
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similar in all commercial preparations. The profile showed a progressive increase in the
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coloration of the liquid during the first six months but, from this moment, (A440-A700)
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values were stable or slightly increased.The initial increase in the coloration of the liquid
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may be related, as in the pH evolution (Figure 2), with the marked increase in the
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environmental temperature during the first month’s storage as spring was advancing.
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The high summer temperatures may have favoured osmotic exchanges of the
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compounds responsible for the colour, and a rapid equilibrium between the pulp and the
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liquid in just 6 months.
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The (A440-A700) rise in the cover brine during shelf-life was related to the increase
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in red tonality, because the CIE a* parameter values increased 5-15 units (Table 3); in
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addition, a very significant decrease in the luminance values (19-33 units) occurs
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simultaneously, which moved the colour toward darker tonalities. The CIE b* parameter
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has a variable evolution, suffering changes of ±15 units in some cases while it only
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changed slightly in others.
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Accordingly, during the packed storage, the cover brine of ripe olives intensified
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the red tonality (a*) and simultaneously suffered a darkening as evidenced by the
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decrease in luminance values (L*).
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Surface olive colour
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In the plain olives of Gordal and Hojiblanca cultivars (Figure 3), a slight increase in the
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reflectance at 700nm (R700) with storage time was observed. The highest R700 increase
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(more than 3 units after 3 years) was recorded for whole Cacereña olives. In pitted
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olives the colour practically remained stable throughout the three years of study.
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The R700 increase in whole olives was related to a slight increase (1-2 units) in
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luminance (L*) and in red tonalities (a*) and a slightly larger increase (2-4 units) in
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yellowness (b*) (data not shown). In pitted olives, the CIE L*, a*, b* parameters did not
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statistically (p<0.05) change during shelf-life in agreement with R700 stability. Therefore,
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only a small initial black discoloration was observed during plain olive shelf-life.
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The colour stability of the pitted olives is due to the greater iron content (> 100
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mg of Fe/ Kg of flesh) than in the whole olives (Table 1) and to the fact that the pH did
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not change during shelf-life (Brenes et al 1985). It is known that higher amounts of iron
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in the olive flesh led to a more intense black surface colour (lower R700) (García et al
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2001). In fact, adding an amount of iron in packed cover brine, as is performed
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industrially, implies a greater amount of fixed iron in pitted olives than in whole olives
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(Garrido et al 1995).
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García et al (2008) fit a first-order kinetic to the degradation of the surface colour
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of ripe black olives in a ASLT test. However, in this study, the fit to the reflectance at
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700nm (R700) curves from pitted samples of Manzanilla, Hojiblanca and Cacereña
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cultivars (Figure 3) of such kinetic was also rather poor (R2 <0.40, Table 2) due to the
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limited changes in R700 (Figure 3).
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On the contrary, in plain olives there were reasonable fits (R2>0.77) and the rate
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constants of R700 increase were very similar to Gordal and Hojiblanca (0.0058 and
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0.0078 month-1) and considerably lower than for the Cacereña cultivar (0.0119 month-1)
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(Table 2). The greater rate constant (p<0.05) in the Cacereña cultivar may be
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associated with the sharp decrease in the cover brine pH (Figure 1) which implies a
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change in colour of iron-phenol complexes as demonstrated by Brenes et al (1995).
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The rate constant values (Table 2) are higher than the average value, 0.003 (±
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0.00045) month-1, extrapolated in the accelerated shelf-life test at 20 ºC (García-García
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et al 2008). This may due to highest temperatures during summer.
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Equation 2 allows for the estimation of the R700 increase after a given period of
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shelf-life. Fixing this as 3 years, it can be calculated that plain olives can increase R700
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between 23 and 54% of their initial reflectance values at 700 nm.
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Firmness
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As seen in Figure 4, the range of the initial values for fruit firmness was high,
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2256-4792 N/100g, which means that some preparations have values twice the levels of
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the others. The difference may be due to many factors, such as fruit ripeness, storage
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time and preservation system prior to darkening (de Castro et al 2007), number and
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NaOH concentration in alkaline treatments (Sánchez-Gómez et al 2006), the recycling
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of preservation solutions (Medina et al 2011) and the possible addition of calcium at
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some stage of processing (de Castro et al 2007).
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Olive firmness decreased with time and its evolution in all cases showed a similar
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profile with seemingly small differences in the degradation rate since firmness evolution
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curves were almost parallel (Figure 4).
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Sánchez-Gómez et al (2013) and García-García et al (2008) fit the evolution of
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texture during the shelf-life of Spanish green olives and black ripe olives respectively to
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first-order kinetics. In this work, the degradation rate constant (k) of firmness ranged
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from (0.0052-0.0096) month-1 (Table 3) and was lower (almost half the value) than the
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rate constants found for Spanish green table olives (0.0119-0.0205) month-1 (Sánchez
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et al 2013). This may be due to more acidic conditions in the green (pH<4.5) than in ripe
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olives (6.0>pH>7.3), a factor that may favour a more rapid deterioration of the texture
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(Brenes et al 1994).
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The softening rate constants in this study (0.0052 month-1 < k < 0.0096 month-1)
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(Table 2) were higher than those obtained by García et al (2008), extrapolated at 20 °C
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(0.0027 month-1 < k < 0.0047 month-1). This may be because during the three summers
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included in the study period, the containers were held at 30 °C or even higher, a fact
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that could have contributed to increasing the firmness degradation rate.
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For the same cultivar, Hojiblanca or Cacereña, the highest values of firmness
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rate degradation (p<0.05) (Table 2) corresponded to olives with the lowest calcium
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concentrations in the flesh (Table 1).
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Fresh olives have a high Ca concentration (Garrido et al 1997) but, to prevent
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softening, the addition of CaCl2 in some phases of the production process is a common
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practice (de Castro et al 2007). In general, olive flesh can absorb Ca and this Ca is not
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released during the different changes in liquids involved in the darkening process.
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Equation 2 allows for the estimation of firmness losses after a given shelf-life
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period. Fixing this as 3 years, it can be calculated that olives can lose between 17 and
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29% of their initial firmness. However, it should be noted (Figure 4) that the range of
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values for this characteristic in the diverse presentations was very wide and even some
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olive samples (plain Gordal and pitted Hojiblanca) had higher final firmness than those
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initially observed in other samples. Apparently, this attribute is not homogeneous and
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strongly depends on the procedures applied by processors.
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There are no lowest firmness limits established for table olive commercialization
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in any standard. However, Sánchez et al (1997) estimated that green table olives with
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values below 1000 N/100 g pitted olive could be considered as a non-marketable
343
product. In this study, no sample had a final firmness lower than this possible threshold
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and all samples of table olives analyzed had the appropriate firmness for
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commercialization.
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Sensory characteristics
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Changes during storage
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No significant changes in the perceptions of external appearance (brightness and skin
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defects), gustatory attributes (odour/flavour to typical olives, salty, bitter, soap taste and
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metallic taste) and kinaesthetic sensations (firmness, fibrousness, crunchiness, skin
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strength and pit release) were observed during the shelf-life of the different commercial
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presentations of the studied ripe table olives.
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The scores of “odour/flavour to typical olives” for most of the samples were above
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the central value of the scale (7.5-9.1) (data not shown), except for the whole Gordal,
356
which always had the lowest values (5.1±0.4).
357
In pitted olives, the panellists did not find any differences (p<0.05) in the surface
358
colour during storage (Figure 5). This is consistent with the objective measures of
359
surface colour (R700) which did not change during the shelf-life (Figure 3). However, in
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plain olives, panellists showed (Figure 5) a decrease in the scores (p<0.05), with the
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largest decline in plain Cacereña olives which also had the highest colour kinetic
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constant degradation value (Table 2).
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Evaluation at the end of shelf-life
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The results obtained for the sensory assessment of all samples by the IOC method
365
(IOC, 2010) at the end of the shelf-life period (Table 4) showed that only plain Gordal
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olives presented a median value of “other defects” higher than 3.0; hence, this sample
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was classified as First, Choice or Select.
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In the remaining samples, no median value of the most frequently perceived
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defect of "negative sensations" ("abnormal fermentation" and "other defects") exceeded
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the 3.0 value threshold. Therefore, pitted Manzanilla, pitted and whole Hojiblanca and
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Cacereña ripe black olives were classified as "extra" commercial category even after 3
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years of shelf-life.
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This is consistent with the absence of alteration during shelf-life, as evidenced by
the maintenance of the vacuum in all containers.
With respect to gustatory sensations, the ripe olives included in this study
376
showed a low intensity of salty, bitterness and acidity because the median values were
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below 4.6.
378
Low salty sensation (range of median values: 3.5-4.6) (Table 4) was due to the
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limited NaCl concentration used in this type of olives. Although there was no statistical
380
difference (p<0.05) in the median scores of the different samples (Table 4), the median
381
values showed good correlation (R2=0.89) with the NaCl concentrations in the cover
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brines (range of averages: 1.2-1.9, Table 1). Such correlation can be considered as an
383
indirect index of the proper performance of the panel.
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As expected, because of the high pH values (usually close to neutrality) of the
385
ripe olives (Figure 2), median values of the acid sensation were low (range: 1.5-2.5).
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The medians of the bitter sensations were also low (Table 4), as correspond to the total
387
removal of the compounds responsible for such taste during the lye treatments (Romero
388
et al 2004; Sánchez-Gómez et al 2006).
389
With regards to the "kinaesthetic sensations", the lowest scores of hardness were
390
obtained for plain Cacereña olives (Table 4) which always presented the lowest shear-
391
compression values throughout the study (Figure 4) and, in fact, this was the only
392
sample with a value slightly below the centre of the scale. The highest median score
393
(8.1) was found in pitted Hojiblanca which also have the highest shear compression
394
values (Figure 4). The rest of samples had hardness values slightly above the centre of
395
the scale (6.3-7.5).
396
There was a moderate variability in the fibrousnesses sensation (Table 4); the
397
lowest sensation was observed in pitted Manzanilla. This cultivar also had the lowest
398
values in Spanish style green table olives (Sánchez-Gómez et al 2013). The rest of
399
samples can be considered somewhat fibrous (range of medians: 5.8-7.3).
400
There was a great variability among samples in crunchiness (range of median
401
values: 2.8-7.3), as shown by the high values of robust standard deviation (Table 4).
402
Plain Gordal and pitted Hojiblanca had a moderate median value, 7.3 and 6.5
403
respectively while the remaining samples showed a low crunchiness sensation.
404
Hence, in agreement with the above comments, all commercial ripe olive
405
presentations included in the study remained stable without any alteration during 3
406
years of shelf-life and even most of them can still be considered as “extra” category,
407
according the sensory evaluation method of the International Olive Council (2004); only
408
plain Gordal olives will be classified as slightly lower quality, “first, choice or select”.
409
410
Conclusion
411
The results found during the ripe olive shelf-life study have shown a marked valley
412
decrease in the pH of cover brine at the beginning of storage followed by a progressive
413
decrease and initial increase in colour. In packed olives, the surface colour showed very
414
limited changes in pitted olives but was slightly more evident in plain fruits which
415
followed a first-order kinetics fading.
416
Fruit firmness degraded during shelf life, according to first-order kinetics. Calcium
417
addition reduced firmness degradation. By the end of the shelf-life time (3 years), olives
418
can lose between 17 and 29% of their initial firmness, although the final products were
419
still adequate for commercialization.
420
No significant changes were observed by the panellists for most of the sensory
421
descriptors studied. Only in whole olives, in which the instrumental colour changes were
422
significant, sensory differences in surface colour were noticeable. In any case, at the
423
end of the shelf life, most of samples were classified as “extra” category, according to
424
the IOC sensory evaluation method and only plain Gordal was classified as “first, choice
425
or select”.
426
From the above mentioned results, it follows that ripe olives do not suffer
427
changes which markedly affect their quality during the current established 3-year shelf-
428
life period. Furthermore, it could eventually be possible that the product preserves its
429
quality for an even longer period of time.
430
431
Acknowledgements
432
This research work was supported by the Spanish Inter-professional
433
Association of Table Olives (INTERACEITUNA) under contract with Instituto de
434
la Grasa nº 20081067.
435
436
23
437
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438
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439
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440
Agricultural and Food Chemistry, 40, 1192–1196.
441
Brenes, M.; García, P.; Garrido, A. (1994). Influence of salt and pH on the
442
firmness of olives in acidic conditions. Journal of Food Quality, 17, 335–
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Brenes, M.; Romero, C.; García, P; Garrido, A. (1995). Effect of pH on the
445
colour formed by Fe-phenolic complexes in ripe olives. Journal of the
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Science and Food Agriculture, 67, 35-41.
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De Castro, A.; Garcia, P.; Romero, C.: Brenes, M.; Garrido, A. (2007). Industrial
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implementation of black ripe olive storage under acid conditions. Journal
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CODEX/COI (1990). Codex standard for table. CODEX STAN 66-1881, as
admended 1990. Roma: FAO.
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European Union. Directive 200/13/EC of the European Parliament and the
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Member States relating to the labelling, presentation and advertising of
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García P.; Brenes, M.;Romero, C.; Garrido, A. (2001). Colour fixation in ripe
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Science of Food and Agriculture, 81, 1364-1370
460
García, P.; Romero, C.; Brenes, M.; Garrido, A. (2002). Validation of a method
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for the analysis of iron and manganese in table olives by flame atomic
24
462
absorption spectrometry. Journal of Agriculture and Food Chemistry, 50,
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3654–3659.
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García-García, P.; López-López, A.; Garrido-Fernández, A. (2008). Study of the
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Garrido, A.; García, P.; Brenes, M.; Romero, C. (1995). Iron content and color
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Garrido Fernández, A.; Fernández Díez, M. J.; Adams, R. M. (1997). Table
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IFST. (1997). Shelf life of foods–Guidelines for its determination and prediction.
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IOOC. (2004). Trade standard applying to table olives. Madrid, Spain:
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IOOC. (2013) On line reference included in World table olives figures:
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production. URL http://www.internationaloliveoil.org/estaticos/view/132-
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world-table-olive-figures. Accessed 2/2013.
479
480
IOOC. (2010). Sensory analysis of table olives. COI/OT/MO No 1/Rev.1.
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López, A.; García, P.; Garrido, A. (2008). Multivariate characterization of table
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olives according to their mineral nutrient composition. Food Chemistry,
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106, 369–378.
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Medina, E.; García, P; Romero, C; Brenes, M. (2011). Recycling preservation
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solutions in black olive processing. International Journal of Food Science
486
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25
487
Montaño, A.; Sánchez, A.H.; Rejano, L. (1988). Método para la determinación
488
del color en salmueras de aceitunas verdes de mesa. Alimentaria, 193,
489
137–139.
490
Panagou, E. Z. (2004). Effect of different packing treatments on the
491
microbiological and physicochemical characteristics of untreated green
492
olives of the Conservolea cultivar. Journal of the Science of Food
493
Agriculture, 84, 757–764.
494
Rejano, L.; Brenes, M.; Sánchez, A.H.; García, P.; Garrido, A. (1995). Brine
495
recycling: its application in canned anchovy-stuffed olives and olives
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Romero, C.; Brenes, M.; Yousfi, K.; García, P.; García, A.; Garrido, A. (2004).
498
Effect of Cultivar and Processing Method on the Contents of Polyphenols
499
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Sánchez, A.H.; Rejano, L.; Montaño, A. (1985). Determinación del color en las
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Grasas&Aceites, 36, 258–61.
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Manzanilla.
503
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(2006).
505
Sánchez, A.H.; Montaño, A.; Rejano, L. (1997). Effect of preservation treatment,
506
light, and storage time on quality parameters of Spanish style green
507
olives. Journal of Agriculture and Food Chemistry, 45, 3881–3886.
508
509
Sánchez-Gómez, A.H.; García-García, P.; Garrido-Fernández, A. (2013).
510
Spanish style green table olive shelf-life. International Journal of Food
511
Science and Technology (in press).
512
513
26
GORDAL-Plain
MANZANILLA-Pitted
HOJIBLANCA-Plain
HOJIBLANCA-Pitted
CACEREÑA-Plain
CACEREÑA-Pitted
7.0
pH
6.5
6.0
5.5
0
6
12
18
24
(months)
30
36
514
515
TIME
Figure 1 pH changes in cover brines during shelf-life. When error bars are not
516
visible, standard deviations were within the ranges of symbols on the graph.
517
518
519
GORDAL-Plain
MANZANILLA-Pitted
HOJIBLANCA-Plain
HOJIBLANCA-Pitted
CACEREÑA-Plain
CACEREÑA-Pitted
(A440-A700)
2.5
2
1.5
1
0.5
0
0
6
12
18
24
30
36
TIME (months)
520
521
Figure 2 Cover brine colour changes (A440-A700) during shelf-life. When error
522
bars are not visible, standard deviations were within the ranges of symbols on
523
the graph.
524
27
GORDAL-Plain
MANZANILLA-Pitted
HOJIBLANCA-Plain
HOJIBLANCA-Pitted
CACEREÑA-Plain
CACEREÑA-Pitted
R700
8
7
6
5
4
3
0
6
12
18
24
30
36
TIME (months)
525
526
Figure 3 Surface colour changes in ripe olives during shelf-life, expressed as
527
reflectance at 700 nm (R700). When error bars are not visible, standard
528
deviations were within the ranges of symbols on the graph.
FIRMNES (N/100 g pitted olive)
529
GORDAL-Plain
MANZANILLA-Pitted
HOJIBLANCA-Plain
HOJIBLANCA-Pitted
CACEREÑA-Plain
CACEREÑA-Pitted
4500
4000
3500
3000
2500
2000
1500
0
530
6
12
18
TIME
24
(months)
30
36
531
Figure 4 Firmness changes in ripe olives during shelf-life. When error bars are
532
not visible, standard deviations were within the ranges of symbols on the graph.
533
534
535
28
SURFACE COLOR
GORDAL-Plain
MANZANILLA-PITTED
HOJIBLANCA-Plain
HOJIBLANCA-PITTED
10
CACEREÑA-Plain
CACEREÑA-PITTED
9
8
7
6
5
0
536
6
12
18
24
30
36
TIME (months)
537
Figure 5 Changes in the perception by panellists of the surface colour (median
538
of observations) during shelf-life. When error bars are not visible, standard
539
deviations were within the ranges of symbols on the graph.
540
29
541
Table 1. Characteristics of the commercial ripe table olives used in the shelf-life study
SAMPLE
Vacuum
Container
(CULTIVAR-Presentation)
(mm Hg)
NaCl
Minerals in olive flesh
(mg / kg)
in cover brine
(%,w/v)
Fe
Ca
GORDAL-Plain
Ca, A10
3.2c (0.7)dfg
1.5c(0.1) d
95e (2) c
1138e (65) bc
MANZANILLA-Pitted
C, 12oz
8.3 (1.6) e
1.8 (0.1) b
100 (3) b
1100 (98) c
HOJIBLANCA-Plain
Jb, 16 Par
12.0 (1.1) c
1.6 (0.1) c
67 (5) d
1045 (53) c
HOJIBLANCA-Pitted
J, 1/4Galon
13.1 (1.3) b
1.2 (0.1) e
107 (4) a
1141 (20) bc
CACEREÑA-Plain
J, 1/4Galon
15.7 (1.3) a
1.6 (0.1) c
60 (8) d
1160 (45) b
CACEREÑA-Pitted
J, 1/4Galon
11.1 (1.5) d
1.9 (0.1) a
102 (5) b
1262 (58) a
542
Note: a C, Tin can; b J, Jar (Glass bottled); c average of 16 samples; d standard deviation in parenthesis;
543
e
average of 3 samples; g Values in column followed with different letters are significantly different (p < 0.05).
544
30
545
546
Table 2. pH of cover brine, surface colour (R700) and firmness changes during shelf-life of different commercial presentation of ripe
table olives. Characteristics of the first-order kinetic fit to data.
pH
SURFACE COLOUR (R700)
FIRMNESS
R700
SAMPLE
k
k
R2
(CULTIVAR-Presentation)
(10-3 months-1)
R2
(10-3 months-1)
Firmness
increase
k
at 3 years
(10-3 months-1)
R2
reduction
at 3 years
(%)
(%)
547
GORDAL-Plain
4.07 (0.20) b
0.95
5.84 (0.28) a
0.98
23
9.61 (2.71) c
0.89
29
MANZANILLA-Pitted
1.54 (0.15) a
0.84
-
0.40
<5
6.98 (0.92) b
0.96
22
HOJIBLANCA-Plain
5.19 (0.62) b
0.81
7.81 (2.24) a
0.80
32
8.96 (2.66) cb
0.84
28
HOJIBLANCA-Pitted
1.90 (0.12) a
0.92
-
0.24
<5
5.60 (1.37) ab
0.88
18
CACEREÑA-Plain
4.58 (0.19) b
0.97
11.92 (3.08) b
0.77
54
9.31 (1.82) c
0.93
28
CACEREÑA-Pitted
1.89 (0.10) a
0.93
-
0.32
<5
5.21 (1.48) a
0.85
17
Note: a Standard deviation in parenthesis; b Values in column followed by different letters are significantly different (p < 0.05).
31
548
Table 3. Changes in the CIE L* a* b* parameters of cover brines during shelf-life in different commercial presentation of ripe olives.
L*
SAMPLE
549
550
a*
b*
(CULTIVAR-Presentation)
Initial
3 years
Initial
3 years
Initial
3 years
GORDAL-Plain
74.2 (2.9)a
53.2 (1.8)
0.9 (0.2)
4.5 (0.8)
21.8 (0.4)
37.5 (0.2)
MANZANILLA-Pitted
63.8 (1.2)
30.7 (0.7)
7.8 (0.2)
16.4 (0.2)
30.5 (0.9)
33.2 (0.4)
HOJIBLANCA-Plain
61.6 (2.9)
19.8 (2.0)
10.7 (2.5)
23.8 (0.7)
36.8 (1.3)
32.0 (1.4)
HOJIBLANCA-Pitted
48.4 (0.3)
17.5 (0.7)
19.3 (0.5)
24.4 (0.3)
47.7 (1.0)
32.0 (1.0)
CACEREÑA-Plain
49.9 (2.8)
30.8 (2.5)
11.9 (0.7)
20.4 (0.2)
36.8 (0.1)
43.1 (3.0)
CACEREÑA-Pitted
52.8 (1.6)
31.1 (0.6)
10.8 (0.1)
16.0 (0.1)
25.0 (0.6)
31.7 (0.3)
Note: a Standard deviation in parenthesis; for each CIE parameter, initial and final values are statically different by all samples
(p<0.05).
551
32
552
Table 4. Sensory evaluation of the commercial presentations of ripe table olives at the end of shelf-life (3 years) according IOC
553
method. Results are medians of 8 observations.
NEGATIVE
SAMPLE
Abnormal
Others
Flavour
defects
GORDAL-Plain
2.2 (0.6)aab
MANZANILLA-Pitted
(CULTIVAR-Presentation)
554
555
556
SENSATIONS
GUSTATORY SENSATIONS
KINAESTHETIC SENSATIONS
Salty
Bitter
Acid
Hardness
Fibrousness Crunchiness
3.2 (0.2)b
3.4 (0.7)a
3.0 (0.6)a
2.4 (0.4)a
7.0 (0.3)ab
6.7 (0.6)ab
7.3 (1.1)ab
1.4 (0.7)a
1.4 (0.2)a
4.6 (0.8)a
2.4 (0.6)a
1.5 (0.3)a
7.5 (0.7)ab
4.8 (0.5)a
3.6 (1.3)ab
HOJIBLANCA-Plain
1.3 (0.2)a
1.3 (0.1)a
4.3 (0.9)a
2.6 (1.1)a
2.5 (0.9)a
6.3 (0.8)ab
5.8 (0.7)ab
4.8 (1.3)ab
HOJIBLANCA-Pitted
1.6 (0.3)a
1.6 (0.3)a
3.5 (0.4)a
3.0 (0.5)a
1.7 (0.6)a
8.1 (0.5)b
7.3 (0.8)b
6.5 (0.8)ab
CACEREÑA-Plain
1.5 (0.2)a
1.8 (0.6)a
4.1 (0.5)a
4.6 (1.2)a
1.7 (0.9)a
5.9 (0.6)a
5.6 (0.7)ab
2.8 (1.4)a
CACEREÑA-Pitted
1.6 (0.3)a
1.7 (0.4)a
4.6 (0.6)a
3.2 (0.6)a
2.2 (0.5)a
6.3 (0.7)ab
6.1 (0.7)ab
5.1 (1.5)ab
Notes: a robust standard deviation in parenthesis; b Medians in each column followed by different letters are significantly different
(p<0.05).
557
33
558
34