DRYING SURPLUS FRUIT – ADDING VALUE TO INCREASE FOOD SAFETY,
YIELD, EFFICIENCY AND SUSTAINABILITY FOR WEST VIRGINIA FRUIT OPERATIONS
Litha
1
Sivanandan ,
Alexandra
2
Smith ,
Kaushlendra
2
Singh ,
Winifred W.
3
McGee ,
Brett
2
Kenney ,
Jacek
2
Jaczynski ,
Judy
1
Matlick ,
Brenda
1
Porter
1. Extension Service; West Virginia University, 2. Davis College of Agriculture, Natural Resources, and Design; West Virginia University, 3. Penn State Extension; Pennsylvania State University.
ABSTRACT
METHODS
West Virginia fruit producers regularly face production and marketing risk, in that they are frequently
unable to sell all the fruit grown. Since the cost of production remains the same, whether fruit is sold,
left un-harvested, or harvested then discarded, it is important to convert the surplus into a valuable
commodity, such as shelf-stable dried fruit. Fruit may then be sold direct to consumers, or whole-sale to
value-added producers, generating revenues. WVU research indicates that pre-treatments such as fruit
firming and/or osmotic dehydration (OD) drying are affordable options for small-scale producers. OD
results in moisture loss and sugar solids gain, thus improving the overall quality and food safety of the
dried fruit products. Spent osmotic solutions (SOS) can be converted into value-added bio-products
using hydrothermal treatment, thereby eliminating regulatory treatment requirements for waste disposal.
INTRODUCTION
Materials:
o 1500g of Sugar Solution (or juice concentrate)
675 grams Sugar+ 825 ml Distilled Water (45°Brix)
975 grams Sugar+ 525 ml Distilled Water (65°Brix)
o 500grams of frozen, scarified berries
Equipment:
o Vacuum Chamber
o Compressed Air/Vacuum Pump
o Refractometer @$1,400(to measure
sugar in °Brix)
o Steam jacketed mixing with agitator
($200)
o Conventional food dehydrator ($100)
o Water activity meter @$2,400 (to
measure water activity)
RESULTS/OUTCOMES
50.0
Water Activity
49.0
Air
Tank
Percent Yield
48.0
46.0
44.0
41.1
42.0
40.0
38.0
0.75
0.74
0.73
0.72
0.71
0.7
0.69
0.68
0.67
0.66
0.65
0.7398
0.7171
0.7003
0.6602
45°Brix/25°C
36.0
45°Brix/50°C
65°Brix/25°C
65°Brix/50°C
Solution Concentration*Temperature
45
65
Solution Concentration in °Brix
Effect of Solution Concentration and Temperature
on Final Water Activity
Effect of Solution Concentration on Percent Yield
After Conventional Drying
50.0
47
48.0
48.0
Percent Yield
EQUIPMENT/MATERIALS
Incubator
Percent Yield
Osmotic dehydration (OD): Fruit is placed in a hypertonic solution (juice
concentrate/sugar) resulting in diffusion of water from the fruit with
Osmotic
Dehydration
concurrent diffusion of the solutes from the solution.
Chamber
Vacuum impregnation (VI): Fruit is placed in a hypertonic solution with a
1:3g/g
decrease in external pressure for a certain amount of time; after which
Fruit
to Solution
external pressure is raised back up to atmospheric pressure.
Shaker
Plate
Pulsed vacuum osmotic dehydration (PVOD): Fruit is placed in a
Schematic of osmotic
hypertonic solution with a decrease in external pressure for a short time,
dehydration apparatus.
followed by a relatively longer OD interval at atmospheric pressure.
Fruit firming: Some fruits are susceptible to textural quality changes during
ripening. Pectin methyl esterase (PME) removes methyl ester groups from
Vacuum
the cell wall pectin constituents, which are accessible to depolymerization
Pump
Vacuum
by polygalacturonase, reducing intercellular adhesiveness and tissue
Chamber
rigidity, and fruit firmness, making fruit-firming a necessary pretreatment.
Research has shown that fruits treated with PME and calcium compound
improves its firmness.
Osmotic
Value-added bio-products using hydrothermal treatment: Hydrothermal Dehydration
Chamber
carbonization (HTC) is defined as a mild form of pyrolysis using an aqueous 1:3g/g Fruit
feedstock. During HTC, biomass is treated in hot compressed water
to Solution
yielding three product forms: solid hydrochar, aqueous compounds, and
Schematic of the Pulsed Vacuum
gases. The hydrochar isolates carbon and serves as chemical adsorbate
Osmotic Dehydration Apparatus.
media for other environmental applications.
Fruit drying research and its industrial applications were disseminated through a series of Extension hands-on
workshops (2011-2014) for educators, agricultural service providers, entrepreneurs, and prospective entrepreneurs.
The resulting 6-hour intensive hands-on training workshops focused on various processes and equipment needed for
increased fruit food safety, overall quality, yield, process efficiency, risks management, target market identification, and
utilization of waste for bio-product applications.
OD: Scarified, frozen blueberries were placed in sugar syrup concentrations of 65°Brix with a fruit to syrup ratio of 1:3
g/g. Fruit and syrup were heated at 50°C for 4 hours with occasional stirring. Weight of fruit was taken before and after
processing for calculating yield. Conventional dehydration was used after osmotic dehydration at 135°F for 6.5 hours.
Sunflower oil was applied to prevent stickiness and to provide a glossy appearance.
Fruit-Firming: PME and calcium chloride was dissolved in water at 105°F. One pound of frozen strawberries was
heated at 105°F in the above solution for two hours. The solution was drained and fruit was processed as stated above
in OD section; drying time might be longer than blueberries.
SOS: Fruit leather preparation, re-concentrating and re-using the syrup etc. are food product development options
trained during the Extension workshops.
HTC: Direct benefits for producing high functionality
hydrochar were discussed. Additionally, indirect benefit
Conventional
for saving millions of gallons of fresh water needed to
Dehydrationreduce biochemical oxygen demand, pH, and total
135°F, 6.5 hours
soluble solids to meet regulatory standards, and
capturing SOS-carbon, reducing green house gas
emission in light of current federal and state regulations.
46.0
44.1
44.0
42.7
42.0
46
45
44
180
240
OD Time in Minutes
Effect of OD Time on Percent Yield After
Conventional Drying
300
43.3
43
42
41
40.0
46.5
25
50
Temperature in °C
Effect of OD Temperature on Percent Yield After
Conventional Drying
Workshops: Hands-on training combined with risk management education, food safety measures, and sustainability
has been an attractive package for participants. Decreased waste, inexpensive costs, high yields (=$$), and shelfstable products were appealing for entrepreneurs. 100% of the participants wanted to learn more about application of
these techniques and were willing to attend another workshop however limited resources restrict us from providing
these workshops and workshops for specific product (fruit) for each region.
Funding: Partial support from National Science Foundation's ADVANCE IT Program under Award HRD-1007978. Any opinions,
findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the
views of the National Science Foundation.
Partial support from Branch Banking and Trust Company’s CRA / Community Development Donation Fund.
Partial support from Northeast SARE Professional Development Grant# ENE12-125
Acknowledgements: Susan Slider, Brett Kenney, West Virginia University.