Antioxidants & it's applications in FF's.

Antioxidants & it's applications in FF's.

1. ANTIOXIDANTS AND THEIR APPLICATIONS IN
FROZEN FOODS.

2. Introduction
• Antioxidants work by either scavenging free radicals or by chelating metals
that can catalyze oxidation reactions. This helps maintain the quality, flavour,
and shelf life of frozen foods.
•An imbalance in the production of free radicals can lead to oxidative
damage to lipids, DNA, and proteins, making them unstable.
•If not neutralized, free radicals can contribute to various diseases affecting
many organs, including Alzheimer's, Parkinson's, stroke, diabetes, and others.

3. Role of Antioxidants in Frozen Foods
•RH → R˙+H˙
•R˙ → R˙+O2 → ROO˙
•2ROOH → ROO˙+RO˙+H2 O
Initiation
•R˙+O2 → ROO˙
•ROO˙+RH → ROOH+R˙
•RO˙+RH → ROH+R
Propagation
•R˙+R˙ →R–R
•R˙+ROO˙ →ROOR
•ROO˙+ROO˙ →ROOR+O2
•Antioxidants+O2 →Oxidized antioxidants
Termination

4. Various
types of
Antioxidants
Dietary
Endogenous
Natural
Synthetic

5. FROZEN FRUITS
•Frozen fruits are widely used in processing industries for various products like juices,
jams, canned goods, desserts, dairy, and bakery products.
•Freezing fruits causes drip loss, enzymatic browning, and softening due to ice crystal
formation and cell disruption, leading to changes in antioxidants, texture, and colour.
•Studies on the effects of freezing and frozen storage on the antioxidant activity (AOA)
of fruits have been conducted on both whole fruits and purees or juices.
Antioxidants and Antioxidant Activity of Fruits and Vegetables

6. Effect of Freezing and Freezing Temperature
•Studies on the effect of freezing on the antioxidant activity (AOA) of whole fruits
generally report no or slight variations.
•Liquid nitrogen freezing or Individual Quick Freezing (IQF) processes did not
significantly change the concentration of phenols, vitamin C, or AOA in fruits like
raspberries, strawberries, blueberries, and others.
•Freezing at higher temperatures also showed minimal effects on AOA in various fruits.
•Freezing can negatively affect the AOA of fruit purees or juices. Freezing of strawberry
pulp, guava puree, and apple puree resulted in decreased AOA as measured by various
assays.
•The effects observed on whole fruits and juices depend on the food's structure. Fruit
disintegration by homogenization or juice extraction before freezing can promote the
activity of oxidise enzymes, leading to a reduction in antioxidants.

7. Effect of Storage and Storage Temperature
Author Poianaet
al.
González
et al.
Ścibisz
and Mitek
Chaovana
likitand
Wrolstad
Sacchett
iet al.
Polinati,
Faller,
and
Fialho
ObservationObserved
a decrease
in AOA of
blueberry,
red
raspberry,
and
blackberr
y during
frozen
storage.
Observed
no AOA
variation
in different
raspberry
cultivars
and wild
blackberry
after one
year of
frozen
storage.
did not
find
differences
in AOA
evolution
in
blueberries
stored at
different
temperatur
es.
observed a
decrease in
AOA of
cherries
stored at
−23 °C but
an increase
at −70 °C.
saw a
decrease
in AOA
of
strawberr
ies at
−80 °C
but an
increase
at −18
°C.
found no
variation
in AOA of
apple
puree and
orange
juice
stored at
different
temperatur
es.

8. Effect of Freezing and Freezing Temperature
•The impact of low temperatures on the antioxidant activity (AOA) of vegetables can be
influenced more by blanching pre-treatments than by freezing itself.
•For example, studies on various vegetables processed by blanching and freezing have
shown a decrease in AOA, attributed to reductions in phenols caused by the blanching
process. However, some studies have shown that proper handling and processing of frozen
foods can retain their functional properties. Properly blanched and frozen vegetables have
shown no significant loss in AOA or vitamin C compared to blanched samples.
•The freezing temperature can affect the freezing rate, which in turn influences ice crystal
size, food texture, and the content of bioactive compounds.
FROZEN VEGETABLES

9. Effect of Frozen Storage and Storage Temperature
•The effects of frozen storage on the antioxidant activity (AOA) of vegetables vary in
studies. Some studies have shown negative effects on AOA, primarily due to reductions
in vitamin C and polyphenols in vegetables like broccoli and cauliflower.
•Other studies have not observed significant losses in AOA during storage at −20°C for
vegetables like peas, spinach, and kale leaves, despite initial losses from blanching and
freezing.
•The storage temperature can impact the quality of frozen plant foods by influencing ice
crystal coarsening. Lower temperatures can preserve antioxidant compounds better, but
the dynamics of high molecular weight bio molecules like enzymes can also be affected.

10. Cryoprotectants and Their Effect on Antioxidant Activity of
Frozen Plant Products
•Cryoprotectants are compounds like sugars, salts, proteins, and hydrocolloids that
prevent damage from freezing. They can be naturally in foods or added during
processing.
•They work through 2 mechanisms, stabilizing the product during freezing.
•Studies have shown that sugars, such as glucose and fructose, can positively impact the
antioxidant activity (AOA) of fruits like sweet and sour cherries, blackberries and
apples.
•The effectiveness of cryoprotectants can vary depending on the fruit and the specific
assay used to determine AOA.
•Some studies have also investigated the use of ice structuring proteins as
cryoprotectants, which have shown positive effects on AOA in cherries.
•The complex interactions between cryoprotectants and antioxidant compounds make it
challenging to predict their effectiveness in preserving specific classes of bioactives.

11. Applications
Preventing Freezer Burn:
Indication: Freezer burn occurs when moisture evaporates from the surface of frozen
foods, leading to dehydration. It is often accompanied by oxidation, which can cause
off-flavours and deterioration in texture.
Application: Antioxidants like ascorbic acid (vitamin C) are used to prevent freezer
burn in frozen fruits and vegetables. By inhibiting oxidation, these antioxidants help
maintain the moisture content and texture of the food, preventing the development of
freezer burn.
Maintaining Colour and Flavour:
Indication:Frozen foods can lose their natural colour and flavour during storage due to
oxidation and other chemical reactions.
Application:Antioxidants can help maintain the natural colour and flavour of frozen
foods, such as meats and seafood. By preventing oxidation, antioxidants preserve the
pigments and flavour compounds in the food, ensuring that they remain visually
appealing and flavourful.

12. Vitamin E (Tocopherols):
Indication: Vitamin E is a potent antioxidant that prevents lipid oxidation, which is
crucial for maintaining the quality of frozen foods.
Application: It is commonly used in frozen fruits, vegetables, and meats to preserve
their color, flavor, and texture. Vitamin E helps extend the shelf life of these products
by protecting them from oxidative rancidity.
Butylated Hydroxytoluene(BHT):
Indication: BHT is a synthetic antioxidant that is effective in preventing the oxidation
of fats and oils in frozen foods.
Application: It is used in a variety of frozen foods that contain fats and oils, such as
frozen meals and snacks. BHT helps maintain the quality and freshness of these
products by preventing the development of off-flavorsand odors.

13. Butylated Hydroxyanisole (BHA):
Indication: Similar to BHT, BHA is a synthetic antioxidant that helps prevent the
oxidation of fats and oils in frozen foods.
Application: It is used in a wide range of frozen foods as a preservative. BHA helps
extend the shelf life of these products by protecting them from oxidative damage.
Rosemary Extract:
Indication: Rosemary extract is a natural antioxidant that has strong anti-oxidative
properties.
Application: It is used in meats, poultry, and some frozen prepared foods to prevent
oxidation and extend shelf life. Rosemary extract is valued for its ability to maintain the
quality and freshness of frozen foods without the use of synthetic additives.

14. THANKS !