Institute of Comparative and Environmental Toxicology and Department of Food
Science, Stocking Hall, Cornell University, Ithaca, New York 14853-7201,
USA.
Consumption of fruits and vegetables has been shown to be effective in the
prevention of chronic diseases. These benefits are often attributed to the
high antioxidant content of some plant foods. Apples are commonly eaten and
are large contributors of phenolic compounds in European and North American
diets. The peels of apples, in particular, are high in phenolics.
During applesauce and canned apple
manufacture, the antioxidant-rich peels of apples are discarded. To
determine if a useful source of antioxidants is being wasted, the
phytochemical content, antioxidant activity, and antiproliferative activity
of the peels of four varieties of apples (Rome Beauty, Idared, Cortland, and
Golden Delicious) commonly used in applesauce production in New York state
were investigated. The values of the peels were compared to those of the
flesh and flesh + peel components of the apples. Within each variety, the
total phenolic and flavonoid
contents were highest in the peels, followed by the flesh + peel and
the flesh. Idared and Rome Beauty
apple peels had the highest total phenolic contents (588.9 +/- 83.2
and 500.2 +/- 13.7 mg of gallic acid equivalents/100 g of peels,
respectively). Rome Beauty and Idared peels were also highest in flavonoids
(306.1 +/- 6.7 and 303.2 +/- 41.5 mg of catechin equivalents/100 g of peels,
respectively). Of the four varieties, Idared apple peels had the most anthocyanins, with 26.8 +/- 6.5 mg of cyanidin 3-glucoside equivalents/100 g
of peels. The peels all had significantly higher total antioxidant
activities than the flesh + peel and flesh of the apple varieties examined. Idared peels had the greatest antioxidant activity (312.2 +/- 9.8 micromol
of vitamin C equivalents/g of peels). Apple peels were also shown to more
effectively inhibit the growth of HepG(2) human liver cancer cells than the
other apple components. Rome Beauty
apple peels showed the most bioactivity, inhibiting cell proliferation by
50% at the low concentration of 12.4 +/- 0.4 mg of peels/mL.
The high content of phenolic
compounds, antioxidant activity, and antiproliferative activity of apple
peels indicate that they may impart health benefits when consumed and should
be regarded as a valuable source of antioxidants.
PMID: 12537430 [PubMed - indexed for MEDLINE]
J Nutr. 2000 Aug;130(8S Suppl):2086S-92S.
Procyanidin content and
variation in some commonly consumed foods.
Hammerstone JF, Lazarus SA, Schmitz HH.
Analytical and Applied Sciences Group, Mars, Incorporated, Hackettstown, NJ
07840, USA.
Procyanidins are a subclass of flavonoids found in commonly consumed foods
that have attracted increasing attention due to their potential health
benefits. However, little is known regarding their dietary intake levels
because detailed quantitative information on the procyanidin profiles
present in many food products is lacking. Therefore, the procyanidin content
of red wine, chocolate, cranberry juice and four varieties of apples has
been determined. On average,
chocolate and apples contained the largest procyanidin content per
serving (164.7 and 147.1 mg, respectively) compared with red wine and
cranberry juice (22.0 and 31.9 mg, respectively). However, the procyanidin
content varied greatly between apple
samples (12.3-252.4 mg/serving) with the
highest amounts on average observed
for the Red Delicious (207.7 mg/serving) and
Granny Smith (183.3
mg/serving) varieties and the lowest amounts in the Golden Delicious (92.5
mg/serving) and McIntosh (105.0 mg/serving) varieties. The compositional
data reported herein are important for the initial understanding of which
foods contribute most to the dietary intake of procyanidins and may be used
to compile a database necessary to infer epidemiological relationships to
health and disease.
PMID: 10917927 [PubMed - indexed for MEDLINE]
J Agric Food Chem. 2003 Mar
12;51(6):1676-83
Apple
peels as a value-added food ingredient. Wolfe KL, Liu RH.
Institute of Comparative and Environmental Toxicology,
Cornell University, Ithaca, New York 14853-7201, USA.
There is some evidence that chronic diseases, such as cancer and
cardiovascular disease, may occur as a result of oxidative stress.
Apple peels have high concentrations
of phenolic compounds and may assist in the prevention of chronic diseases.
Millions of pounds of waste apple peels are generated in the production of
applesauce and canned apples in New York State each year. We proposed that a
valuable food ingredient could be made using the peels of these apples if
they could be dried and ground to a powder without large losses of
phytochemicals. Rome Beauty apple peels were treated with citric acid dips,
ascorbic acid dips, and blanches before being oven-dried at 60 degrees C.
Only blanching treatments greatly preserved the phenolic compounds, and
peels blanched for 10 s had the highest total phenolic content. Rome Beauty
apple peels were then blanched for 10 s and dried under various conditions
(oven-dried at 40, 60, or 80 degrees C, air-dried, or freeze-dried). The
air-dried and freeze-dried apple peels had the highest total phenolic,
flavonoid, and anthocyanin contents. On a fresh weight basis, the total
phenolic and flavonoid contents of these samples were similar to those of
the fresh apple peels. Freeze-dried peels had a lower water activity than
air-dried peels on a fresh weight basis. The optimal processing conditions
for the ingredient were blanching for 10s and freeze-drying. The process was
scaled up, and the apple peel powder ingredient was characterized. The total
phenolic content was 3342 +/- 12 mg gallic acid equivalents/100 g dried
peels, the flavonoid content was 2299 +/- 52 mg catechin equivalents/100 g
dried peels, and the anthocyanin content was 169.7 +/- 1.6 mg cyanidin
3-glucoside equivalents/100 g dried peels.
These phytochemical contents were a
significantly higher than those of the fresh apple peels if calculated on a
fresh weight basis (p < 0.05). The
apple peel powderhad a total
antioxidant activity of 1251 +/- 56 micromol vitamin C equivalents/g,
similar to fresh Rome Beauty peels on a fresh weight basis (p > 0.05). One
gram of powder had an antioxidant activity equivalent to 220 mg of vitamin
C. The freeze-dried apple peels also had a strong antiproliferative effect
on HepG(2) liver cancer cells with a median effective dose (EC(50)) of 1.88
+/- 0.01 mg/mL. This was lower than the EC(50) exhibited by the fresh apple
peels (p < 0.05). Applepeel powder
may be used in a various food products to add phytochemicals and promote
good health.
