oxygenmagAU Jan/Feb 2018 69
ROUND 2
The study: Compared six vegetables — beet
greens, spinach, broccoli, carrot, onion, and
celery — for their antioxidant compounds
(called the ORAC value) for fresh versus
frozen processing. The ORAC value depends
on the quality and quantity of the antioxidants
contained in the vegetable.
Findings: Four of six frozen
vegetables showed lower
phenolic and ORAC values
than the fresh vegetables. The
results suggest that people
who use frozen vegetables will
have a 30 to 50 per cent drop in
antioxidant capacity compared
to those who eat an identical
amount of fresh vegetables.^3
SCORE: FROZEN 0 –
FRESH 1ROUND 3
The study: Nitrite and
nitrate levels in frozen
and fresh broccoli were
measured.
Findings: Fresh broccoli
had only traces of nitrites
and low levels of nitrates.
Freezing the broccoli gave
rise to an increase in the nitrate
levels, possibly due to the quality
of water used. However, cooking
decreases nitrate levels, leaving
no difference in the levels of
reduction between fresh and
frozen status, and nitrite levels
were scarcely affected by freezing
or by cooking.^4
SCORE: FROZEN 0- FRESH 0
ROUND 4
The study: A variety of vegetables were
measured for changes in carotenoids, vitamin
E, minerals, and fibre.
Findings: Results found that these nutrients
were generally similar in comparison for fresh,
frozen, and canned vegetables. It was noted
that minerals and fibre are generally stable, but
may be lost in peeling and cooking processes.
Added sodium can change the natural mineral
composition of a product, so choose a ‘no salt
added’ item.^5
SCORE: FROZEN 0 – FRESH 0ROUND 5
The study: Focused on fresh versus frozen
Brassica vegetables.
Findings: Fresh Brassica vegetables were able
to retain phytonutrients and antioxidants
better than frozen samples overall.^6
SCORE: FROZEN 0 – FRESH 1ROUND 6
The study: Kale, spinach, and New Zealand
spinach were tested for contents of mineral
content comparing with fresh and frozen and
then cooked.
Findings: Frozen products prepared for
consumption contained significantly less
potassium, magnesium, phosphorus, and
copper. There was also a decrease in calcium,
but only in the kale, and a decrease in
chromium and nickel in the New Zealand
spinach only.^7
SCORE: FROZEN 0 – FRESH 1ROUND 7
The study: The effect of long-term freezer
storage on the mineral and antioxidant content
of more than 20 vegetables was investigated.
Findings: Fibre content remained the same;
some minerals were lost, but mostly remained
stable. However, significant losses of up to
20 to 30 per cent in antioxidant activity were
discovered. Large amounts of folic acid and
vitamin C contents were lost during blanching,
but became stable during freezer storage.^8
SCORE: FROZEN 0 – FRESH 1ROUND 8
The study: Most of the studies assessing
antioxidant levels in frozen vegetables are
based on both hydrophilic and lipophilic
properties in combination. Hydrophilic
are affiliated with water and lipophilic are
affiliated with fat. This study chose to analyse
only the antioxidants of a hydrophilic nature in
carrots, zucchini, tomatoes, green beans, peas,
and yellow peppers.
Findings: Overall, the decrease in hydrophilic
antioxidants after cooking was relatively small
and not likely to cause a significant decrease in
antioxidant intake.^9
SCORE: FROZEN 1 – FRESH 0FINAL RESULT: FROZEN 2 – FRESH 4It’s not a significant difference, but by a margin
the winner is fresh is best.
The outcome here demonstrates that
including both fresh and frozen produce in
your diet will more than accommodate your
requirements — but, more importantly, the
results should serve to encourage you to
ensure a wide variety of fruits and vegetables
are included in your diet.REFERENCES(^1) Mazzeo, T., et al. (2011). Food Chemistry 128(3): 627-33. 2 Favell, D. J. (1998). Food Chemistry 62(1): 59-64. (^3) Ninfali, P., & Bacchiocca, M. (2003). Journal of Agricultural
and Food Chemistry 51(8): 2222-26.^4 Huarte-Mendicoa, J. C., Astiasarán, I., & Bello, J. (1997). Food Chemistry 58(1): 39-42.^5 Rickman, J. C., Bruhn, C. M., & Barrett, D.
M. (2007). Journal of the Science of Food and Agriculture 87(7): 1185-96.^6 Pellegrini, N., et al. (2010). Journal of Agricultural and Food Chemistry, 58(7): 4310-21.
(^7) Lisiewska Z, Gębczyński P, Bernaś E, Kmiecik W. (2009). Journal of Food Composition and Analysis 22(3):218-23. (^8) Puupponen-Pimiä, R., et al. (2003). Journal of the
Science of Food and Agriculture, 83(14):1389-02.^9 Danesi, F., & Bordoni, A. (2008). Journal of Food Science 73(6): H109-12.