Nutrient Loss in Foods
Due to Processing and
Storage
Susanne Talcott
Assoc. Professor
Nutrition and Food Science
Texas A&M University
Luke R. HoLukeward, Ph.D.
Overview
• Processing Techniques
• Examples of Nutrients
– Minerals
– Vitamins
– Botanicals (Polyphenols)
Loss of Minerals Due to Processing
What impacts minerals in foods
– Depleted soils vs. volcanic soils
– Organic vs. conventional practices
– Selective breeding vs. genetic manipulations
– Food composition (fiber, chelators)
– Processing?
Food Processing
– Peeling (physical or chemical)
– Dehulling
– Trimming/Slicing (sharp or dull knife)
– Altering redox states (ie. Added antioxidants)
– Concentration/dehydratation/membrane filtration
– Soaking, blanching, boiling, frying, brining
– Grinding
– Roasting and toasting to induce Maillard-complexes
– Enzyme treatments (ie. Phytase)
– Brewing, steeping, fermenting
– Additives: enrichment and fortification
Food Composition vs Activity
• Minerals that are present may not be bioavailable
– “100%” present pre-processing
– Assume some physical loss with processing
• Processing may increase/decrease bioavailability
– Fiber breakdown (physical or enzymatic)
– Particle size reduction
– Starch hydrolysis
– Anti-nutritionals (oxalates, phytates, and other chelators)
• Unavailable minerals are still part of its nutritional profile
• Released minerals are often detrimental to food quality
– AsA + Copper + O2 = superoxide radicals
Mineral Analysis
Minerals from Ashes
• ASH is the residue remaining in a food after complete
combustion (oxidation).
• What is in foods that won’t burn ???
• How Hot? Total ash determinations may range from 400 to
700°C
• There are 2 common methods of ashing:
–
DRY
– WET
How Does Ash Relate to Proximate
Analysis?
• What are the proximates
– Moisture, Protein, Fat, Carbohydrate
• Sum of other Proximates + Ash = ~100%
Ash Content in Common Foods
•Most fluid dairy products
•Evaporated milk
•Nonfat dry milk
•Pure fats; oils; and shortenings
•Fresh fruits
•Dried fruits
•Vegetables
•Pickles/sauerkraut/ butter
•Beans
•Fresh meat and poultry
0.5- 1.0%
1.5%
8%
0%
0.2 - 0.8%
up to 3.5%
1.0%
NaCl added
4%
1%
What is Really in the Ashes?
•
•
•
•
•
•
•
•
•
Calcium (most all foods except sugar, starch or oil)
Phosphorus (dairy, grains, nuts, meats, poultry products)
Iron (enriched foods, grains, nuts; meats, eggs, legumes
Sodium (primarily from added salt)
Potassium (dairy products, F&V, cereals, nuts, meats)
Magnesium (nuts, cereals, legumes)
Manganese (cereals, F&V, meats)
Copper (sea foods, liver, cereals, vegetables)
Zinc (sea foods)
These can be tested for individually by other methods:
Atomic absorption (AA) spectroscopy
Inductively coupled plasma (ICP)
Ash Determination….
• DRY ASHING
– Use of a muffle furnace capable of maintaining 500-600 °C.
– Water and volatiles are vaporized and organic compounds are
oxidized into H2O, CO2, CO, and oxides
– Most minerals are converted to oxide (NO2, CaO, Fe2O3),
sulfates, phosphates, chlorides and silicates.
– Some minerals are volatile (Fe, Se, Pb, Hg) and dry ashing
temperatures should be carefully monitored.
• WET ASHING
– Use acids alone or in combination with other oxidizing agents.
– Nitric, hydrochloric, or perchloric acid are used.
Food Processing Examples
Cereal Grain
Rice Milling
• Remove husk, bran, germ by rubbing with
abrasive disks or rubber belts
• Polish endosperm to glassy finish
• Removes bran/germ and nutrients
• Brown rice = very little milling
Rice
Rice Enrichment
• Add some vitamins, minerals
• Coat rice with nutrients (B-vits, minerals)
Parboiling or steeping (converted rice)
• “Cook” rice before milling (~10 hrs, 70°C)
• Nutrients, vitamins and minerals, will migrate
into endosperm (no fortification)
Canning in the Literature
• Trace minerals were shown to decrease during
canning, presumably due to minerals diffusing
into the cover solution (Saldamli, 2007).
• Most food minerals are water-soluble, so
losses are greatest during water-based
processes such as boiling (Cermeroglu, 2009)
• Cover solution composition, pH, particle size,
surface area, and temperature all play a role
(Clydesdale, 1991; Saldamly, 2007).
Strawberry and Plum Canning
(Yagmur and Taskin, 2011)
•
•
•
•
•
•
•
•
•
•
Raw fruits
Slicing, de-seeding, leaf/stem removal
1st wash and sorting (water turns light red)
2nd wash
Can washing
Filling with fruit
Cover solution (ie. sugar-water)
Thermal processing
Strain fruit from cover solution
Analyze for trace minerals by AA
Strawberry and Plum Canning
(Yagmur and Taskin, 2011)
• Results: Trace minerals decreased in the fruit
following thermal processing in both fruits…???
Raw
Fe 5.84
Cu 0.45
Zn 0.86
Mn 0.53
Plums (ppm)
Wash Canned Syrup Entire Can
4.70
2.61 2.17
4.78
0.41
0.31
0.09
0.40
0.81
0.68
0.13
0.81
0.45
0.40
0.09
0.49
Strawberry (ppm)
Raw Wash Canned Syrup Entire Can
Fe 5.08 4.72
4.60
2.81 7.41
Cu 0.49 0.41
0.36
0.05
0.41
Zn 0.89 0.84
0.72
0.10
0.82
Mn 2.51 2.34
2.11
0.14
2.25
Pectin
and
Minerals
Ca+2
Ca+2
Ca+2
Ca+2
Ca+2
Ca+2
Overall Effect of Processing on Minerals
• Minerals are not really sensitive to the heat of food
processing
– But they can leach out during processing into
cooking medium (water/oil).
• Some foods are more susceptible to lose than others
– 50% decrease for manganese, cobalt, and zinc for
canned spinach/beans
• Mineral loss can be re-captured into soup, gravy, or
sauces
• Hard water can increase calcium, magnesium and iron
• Soft water can increase sodium.
• Processing to decrease phytates, oxylates, and
breakdown of insoluble fiber can improve mineral
bioavailability
Loss of Vitamins Due to Storage
and Processing
How can Vitamins Be Loss
• Removal
• Leaching into processing solution
• Degradation due to heat or interactions with
other food components
Do Canned Foods
Lose Nutrients?
• Fat-soluble vitamins and most minerals are
relatively stable
– Not affected much by canning
• Three vulnerable water-soluble vitamins
– Thiamin
– Riboflavin
– Vitamin C
Example 1: Thiamine
Thermal Degradation of Vitamin B1
H2N
Cl
+
N
-
H2C
N
N
HO
S
Thiazol
Pyrimidine
Degradation of Thiamine under Basic Condition
H2N
Cl+ HC
N 2
HO
S
N
N
-
H2N
OH-
+ H2O
N
HO
+
N
CH3
S
N
no odor
( Coffee aroma with meaty note )
Degradation of Thiamine under Acidic Condition
H2N
N
H2N
N
H3C
N
HO
+
H+
H2C
N
+ H2O
H H2C
H3C N
C H
HO
S
N
+ H2O
S
CHO
H2N
O
HO (CH2)2 CH C CH3
SH
Coffee
+
HCOOH
+
H2N
H+
N
N
No odor
Formation of Thiazole Compounds from Thiamine
N
HO
S
-H2O
N
Reduction
S
Cocoa
Methyl-vinyl-thiazole
N
S
(Cocoa, beef)
Methyl, ethyl-thiazole
Formation of Furan Compounds from Thiamine
O
H3C-C-CH-CH2-CH2-OH
SH
-SH
+H
+
O
H3C-C-CH2-CH2-CH2-OH
Cyclization
From the decomposition of
thiamin under acidic condition
C
O
OH
CH3
Reduction
-H2O
O
CH3
-H2
CH3
O
( Coffee, tea )
Formation of Furan Compounds from Thiamine
O
-H2S
H3C-C-CH-CH2-CH2-OH
H2O
SH
O
OH
keto enolization
H3C-C-CH-CH2-CH2-OH
H3C-C=C-CH2-CH2-OH
OH
OH
OH
H3C-CH-C-CH2-CH2-OH
O
O
-H2O
Roasted onion, beef, tomato, white bread
O
CH3
Reducing nutrient loss
To reduce the loss of fat-soluble vitamins A
and E, cook with very little oil, e.g. grilling or
baking.
In order to reduce the loss of watersoluble, oxygen-sensitive vitamin C, fruits
and vegetables should be cooked using
minimal amount of water and cooking time
as possible.
Most minerals are unaffected by heat. However,
potassium can leach (release from cells of food)
into cooking liquids.
Reducing nutrient loss
When vegetables are prepared (e.g.
chopping) the cell walls are broken.
An enzyme called ascorbic acid
oxidase escapes, mixes with and then
destroys the vitamin C. The enzyme is
destroyed by heat.
To reduce loss of vitamin C:
• use a sharp knife, keep chopping and shredding to a minimum;
• prepare vegetables just before use;
• do not store the food in water;
• use a small amount of water when cooking;
• avoid over cooking as the enzyme is destroyed quickly;
• serve immediately after cooking.
Loss of Polyphenols from Plantbased Foods
Fruits and Vegetables are Living Systems
Postharvested Fruits and Vegetables:
• Breathe, Eat, Sleep, Tired, Sick, Die
• Enzymes still very active
• Softening, color change, etc.
• Respiration continues long after harvest
• Production of water, heat
– Glucose + oxygen => CO2 + H2O + Heat
• Transpiration continues
– Loss of water (wilting) due to evaporation
Factors Influencing Phytonutrient Content of
Fruits and Vegetables
• Genotype
• Cultural practices
• Environmental growing
conditions
• Maturation
• Postharvest handling and storage
conditions
• Processing
Luke Howard, Food Science Department, University of Arkansas
Chemical and Physical Factors Influencing the
Stability of Vitamins and Phytonutrients
•
•
•
•
•
•
•
•
Heat
Light
Oxygen
Co-factors
Metals
Enzymes
Chemical structure/solubility
Tissue localization: Free vs bound
Luke Howard, Food Science Department, University of Arkansas
Processing Factors Influencing Phytonutrient
Content
• Unit operations
Washing/cleaning
Physical removal of tissues
Soaking (beans and peas)
Blanching (steam vs water)
Particle size reduction
Enzyme treatments, pressing, clarification
Luke Howard, Food Science Department, University of Arkansas
Processing Factors Influencing Phytonutrient
Content
•
•
•
•
Filling and Brining
Ratio of product:brine
Dissolved oxygen
Food additives
Luke Howard, Food Science Department, University of Arkansas
Processing Factors Influencing Phytonutrient
Content
Preservation method
Thermal process (time
and temperature, still vs
agitated, aseptic)
Freezing process (rate
and temperature)
Luke Howard, Food Science Department, University of Arkansas
Factors Influencing Phytonutrient Content of
Fresh-cut Products
•
•
•
•
•
Washing/sanitizing
Peel removal
Degree of wounding
Package atmosphere
Storage temperature
Luke Howard, Food Science Department, University of Arkansas
Processing of Blueberries –
Effects on Polyphenolics
Luke Howard, Food Science Department, University of Arkansas
Fresh Berries
(Blueberries, Blackberries, Black raspberries)
Analysis of Fresh Berries
Frozen Berries
Juice
Puree
Individually Quick Frozen (IQF)
Canned (Syrup)
Clarified
Baking
Canning
Canned (Water)
Non-Clarified
Pie-Canned in
Water
Pie-Frozen
Berries
Sampling: 1 d, 1 mo, 3 mo, 6 mo
Luke Howard, Food Science Department, University of Arkansas
Total Anthocyanin Retention and Polymeric
Color in Blueberry Juices
100
25
90
20
70
60
15
50
40
10
30
20
5
% Polymeric color
% Retention
80
10
0
0
P
1 (mo)
NonClar-ACY
3 (mo)
Clar-ACY
6 (mo)
NonClar-PC
Clar-PC
Luke Howard, Food Science Department, University of Arkansas
Total Anthocyanin Retention and Polymeric
Color in Canned Blueberries
100
40
90
35
80
% Retention
70
25
60
50
20
40
15
30
10
% Polymeric color
30
20
5
10
0
0
P
1 (mo)
Water-ACY
3 (mo)
Syrup-ACY
Water-PC
6 (mo)
Syrup-PC
Luke Howard, Food Science Department, University of Arkansas
% Retention
Total Anthocyanin Retention in Blueberries
Canned in Syrup
100
90
80
70
60
50
40
30
20
10
0
Syrup
Berries
P
1 (mo)
3 (mo)
6 (mo)
Luke Howard, Food Science Department, University of Arkansas
Total Anthocyanin Retention and Polymeric
Color in Blueberry Puree
100
45
90
40
80
35
% Retention
30
60
25
50
20
40
15
30
10
20
10
5
0
0
P
1 (mo)
3 (mo)
ACY
% Polymeric Color
70
6 (mo)
PC
Luke Howard, Food Science Department, University of Arkansas
Total Flavonol Retention in Blueberry Juices
100
90
% Retention
80
70
60
Non-clarified
Clarified
50
40
30
20
10
0
P
1 (mo)
3 (mo)
6 (mo)
Luke Howard, Food Science Department, University of Arkansas
% Retention
Total Flavonol Retention in Blueberries Canned
in Syrup
100
90
80
70
60
50
40
30
20
10
0
Syrup
Berries
P
1 (mo)
3 (mo)
6 (mo)
Luke Howard, Food Science Department, University of Arkansas
Total Flavonol Retention in Blueberry Puree
100
90
% Retention
80
70
60
50
40
30
20
10
0
P
1 (mo)
3 (mo)
6 (mo)
Luke Howard, Food Science Department, University of Arkansas
% Retention
Chlorogenic Acid Retention in Blueberries
Canned in Syrup
100
90
80
70
60
50
40
30
20
10
0
Syrup
Berries
P
1 (mo)
3 (mo)
6 (mo)
Chlorogenic Acid Retention in Blueberry
Puree
100
90
% Retention
80
70
60
50
40
30
20
10
0
P
1 (mo)
3 (mo)
6 (mo)
ORACFL Retention in Blueberry Juices
100
90
% Retention
80
70
60
Non-clarified
Clarified
50
40
30
20
10
0
NP
P
1 (mo)
3 (mo)
6 (mo)
ORACFL Retention in Canned Blueberries
100
90
% Retention
80
70
60
Water
Syrup
50
40
30
20
10
0
P
1 (mo)
3 (mo)
6 (mo)
ORACFL Retention in Blueberry Puree
100
90
% Retention
80
70
60
50
40
30
20
10
0
P
1 (mo)
3 (mo)
6 (mo)
This is all for the exam 
Phenolic and Antioxidant
Changes in Fresh-cut Carrots
Processing and Sampling
• Carrot coins (with peel removed)
packed in ventilated bags
• Stored at 4oC
• Sampled at 0, 3, 7, 14 and 21 days
Chemical Analyses
• Phenolics – HPLC
HCA quantified as chlorogenic acid
equivalents at 320 nm
pHBA quantified as hydroxybenzoic acid
equivalents at 265 nm
• Carotenoids – HPLC C30 column
Beta, alpha and carotene isomers quantified
as beta carotene equivalents
HPLC
chromatogram
of a canned
sample (at 450
nm) with the
peak maxima
for all-trans(1)
lutein, (6) carotene, and
(7) -carotene.
Other labeled
peaks: (2) 13cis , (3) 13’cis , (4) 15cis , (5) 13cis , and (8)
9-cis .
PCL Antioxidant Assay
• Antioxidant capacity
Measured using a Photochem® antioxidant analyzer
L + hv + O2
L.+ + O2.-
• Detection of excess superoxide radicals left after
quenching by antioxidants
O2.- + L.+
L (luminescence)
HCA and pHBA Contents of Fresh-cut Carrots
During Storage
25
HCA
pHBA
20
20
15
15
10
10
5
5
0
0
0
5
10
15
Storage Time (days)
20
25
pHBA (mg pHBAE/100 g FW)
HCA (mg CAE/100 g FW)
25
AOX Capacity (umol TE/100 g FW)
Antioxidant Capacity of Fresh-cut Carrots as
Affected by Storage
350
300
250
200
150
100
50
0
0
5
10
15
Storage Time (days)
20
25
Relationship Between HCA Content and
Antioxidant Capacity
AOX Capacity (umol TE/g FW)
300
250
R2=0.988
200
150
100
50
0
0
2
4
6
8
10
12
HCA (mg CAE/100 g FW)
14
16
18
Alpha, Beta and Total Carotene Contents of
Fresh-cut Carrots as Affected by Storage
Total Carotene (mg/100g FW)
12
10
Alpha
Beta
Total
8
6
4
2
0
5
10
15
Storage Time (days)
20
25
Other Studies
Effect of Cooking on Total Flavonoid Content of
Spinach
Concentration (mg/kg FW)
1200
1000
800
600
400
200
0
Fresh
Cooking
Water
Cooked
Tissue
Sum
Gil et al. (1999) J. Agric. Food Chem., 47, 2213-2217.
Effects of Thermal Processing and Canned Storage on
Total Phenolic Content in Peaches
Total phenolics (mg/kg FW)
400
350
300
250
213F (40 min)
220F (10 min)
230F (2.4 min)
200
150
100
50
0
0
3
6
Storage Time (months)
Asami et al. (2003), J. Sci. Food Agric., 83, 56-63
Comparison of Individual Procyanidin Oligomers in
Frozen and Canned Clingstone Peaches
Normalized Peak Area
0.6
0.5
0.4
0.3
Frozen
Canned
0.2
0.1
0
M
o
on
m
er
m
Di
er
im
Tr
er
T
m
ra
t
e
er
Pe
am
t
n
er
er
am
am
t
x
p
He
He
er
Asami et al. (2003), J. Sci. Food Agric., 83, 56-63
Total Flavonoid Content of Frozen Vegetables
During Storage
Total flavonoids (mg/kg DW)
800
700
600
500
Fresh
Blanched
6 mo
12 mo
400
300
200
100
0
Cauliflower
Broccoli
Cabbage
Puupponen-Pimia et al. (2003), J. Sci. Food Agric., 83, 1839-1402
Total Carotenoid Content of Frozen Vegetables
During Storage
Total Carotenoids (mg/100g DW)
4.5
4
3.5
3
Fresh
Blanched
6 mo
12 mo
2.5
2
1.5
1
0.5
0
Pea 1
Pea 2
Carrot 1 Carrot 2 Spinach
Puupponen-Pimia et al. (2003), J. Sci. Food Agric., 83, 1839-1402
% Retention
Retention of Flavonoids in Canned Green Beans
Price et al. (1998) J. Agric. Food Chem., 46, 4898-4903.
Retention of Polyphenolics in Pasteurized
Blueberry Juice
60
40
30
20
10
ac
id
hl
or
og
en
ic
C
Pr
oc
ya
ni
di
ns
no
ls
Fl
av
o
nt
ho
c
ya
ni
ns
0
A
% Retention
50
Skrede et al. (2000), J. Food Sci., 65, 357-364
Concentration (mg/100g FW)
Effect of Cooking on Procyanidin Content of
Pinto Beans
800
700
Monomers
Dimers
Trimers
4-6 mers
7-10 mers
> 10 mers
Total PCs
600
500
400
300
200
100
0
Raw
Simmered
Gu et al. (2004) J. Nutr. 134: 613-617
Changes in Antioxidant Activity as Affected
by Heating
Nicoli et al. (1999) Trends Food Sci. Tech. 10:94-100
Changes in the Overall Antioxidant
Properties of Foods as Affected by Heating
No changes
• No changes in naturally occurring AOX
• Loss of native AOX = formation of compounds
with novel or improved AOX
• Improvement of AOX properties of native
compounds
• Formation of novel compounds having AOX
properties (MRPs)
Nicoli et al. (1999) Trends Food Sci. Tech. 10:94-100
Conclusions
• Different unit operations and preservation
methods markedly affect the retention of fruit
and vegetable phytonutrients and antioxidant
capacity
• Increased number of processing steps
exacerbates phytonutrient losses
• Processing by-products are a potentially rich
source of phytonutrients
• Water-soluble phytonutrients readily leach
into liquid canning media
Conclusions
• Fresh-cut produce may exhibit high
antioxidant capacity due to the synthesis and
accumulation of wound-induced phenolic
compounds
• Mitigation strategies are needed to prevent
losses of phytonutrients during processing
• More research is needed on the bioavailability
of phytonutrients in processed foods