3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
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seniors: total 13, age 68.5 ± 7.16; 10 F/3 M,
juniors: total 8, age 27.13 ± 3.63; 6 F/2 M.
Results
Antioxidant levels in apples are relatively low. Differences
were observed according to fruit colour (variety) – high
content was found mainly in yellow sorts (Golden Delicious).
Freezing led to very low changes of antioxidant levels. Controlled
drying caused concentration of all antioxidants including
ascorbate.
Apple surface natural microflora contained mostly
moulds and yeasts. Artificial infection of long-term stored
apples (158 days) was more intensive in apples stored under
normal atmosphere than under controlled storage conditions
(fluctuated anaerobiosis).
Total phenolic and flavonoid levels differed according
to apple sort and colour. A part of phenolics formed by flavonoids
was in range of 30–60 %. Ascorbate levels detected in
apples were in range 12–51 mg kg –1 . In Idared apples about
4 × higer content of ascorbate was found when compared
with Jonagored apple. Concentrations of individual flavonoids
(chlorogenic acid, morin, quercetin, rutin) carotenoids
(lycopene, beta-carotene) and catechins ((–)catechin, catechin
gallate, epicatechin) differed slighty according to apple sort.
These substances exhibited significant contribution to final
colour of apple fruits. Their content in apples was relatively
low. TAS levels were related to the content of phenolics and
flavonoids, no direct correlation was found. Antimutagenicity
corresponded to TAS.
Freezing is very suitable procedure for long-term conservation
without significant changes of active substance
content. After drying under regulated conditions (12 hours,
50 °C) the highest decrease was observed in ascorbate level
(62 %), TAS level decreased by 42 %, flavonoids and phenolics
content decreased by 40–50 %. Regulated drying has
probably no significant negative effect on biological activity
of apples with regard to amount of dried fruit intake.
Long-term storage (158 days) led to some increase in
levels of total as well as individual antioxidants in all studied
sorts. The highest level of all antioxidants was found
in Idared variety, which is characteristic by the lowest longterm
stability. Levels of most of antioxidants in apples stored
under modified atmosphere were also lower than under RA.
It seems that great group low molecular weight as well as
s625
high molecular weight antioxidants is mobilized in overriped
or damaged fruits, the higest response was observed in Idared
apples. Simultaneously, this variety was very sensitive to artificial
mould infection, fruit damage after artificial infection
was in this sort the highest from all studied apple varieties.
Thus, some unbalance in apple antioxidant status could be
accompanied with increased sensitivity to mould infection.
In stored apples some antioxidant enzymes were analyzed
too. The highest activity exhibited catalase (CAT) followed
by superoxide dismutase (SOD). Level of polyphenoloxidase
(PPO) was very low. Activities of CAT and PPO
were lower in apples stored under regular than under modified
atmosphere, while SOD activity was higher in apples
stored under FAn. In red varieties the antioxidant enzymes
exhibited higher values than in the green ones. Mainly CAT
and PPO are mobilized on overriped and/or slightly damaged
apples.
Sensory analysis results obtained in two gorups of agedifferent
subjects showed that in both groups no significant
differences in evaluation taste, aroma, colour and texture in
4 sorts of apples were found. The lowest degree of consumer
acceptance was found in Idared apple, while Jonagold was
the most prefferd sort from analyzed apples. In general, red
apple sorts were better accepted than green sorts. Both group
preffered fresh apples than dried fruits. Apple intake in senior
group (1 apple daily, on average) was about 2 × higher than
in junior group.
Conclusions
In general, apples contain a large number of different
low-molecular weight as well as enzyme antioxidants, but
levels of individual derivatives are relatively low. However,
high intake of apples confirmed by questionnaire analysis can
lead to cumulative effect. Thus, apples are one of the most
important sources of natural antioxidants in Czech population
(average intake in population is about 600 g per week).
At present, more than 90 % of produced apples are
being stored and the losses range from 5 % to 25 %. Study of
modern storage technologies and their influence of fuit quality
and consumer acceptability is very important problem.
This work has been partially supported by project
QH81056 of the Ministry of Agriculture of the Czech
Republic.