Apple Peels as a Value-Added Food Ingredient

Abstract

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 powder had 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). Apple peel powder may be used in a various food products to add phytochemicals and promote good health.

Current options for the valorization of food manufacturing waste: a review

“…Due to large quantity of produced apple pomace, the preparation of single product would not be economically feasible and production of alternative products should be explored. Million pounds of waste apple peels are also generated in apples industry each year (Wolfe and Liu, 2003), with high costs of disposal and threat to the environment. Several studies focused on apple peel properties, due its high content of phenolic compounds and antioxidants.…”

“…High concentrations of phenolic compounds in apple peels may support the prevention of chronic diseases, such as cardiovascular diseases and cancer. In their review, Wolfe and Liu (2003), stated that valuable food ingredient could be made using the waste peels, trough drying and grounding processes without large losses of phytochemicals. Rome Beauty apple peels were treated with citric acid dips, ascorbic acid dips, and blanches and dried under various conditions.…”

“…Finally, it is remarkable that the risk of excessive manipulations and modification of food could be critical in some cases; this issue should be further investigated to avoid potential risks to consumers' health. Henríquez et al, 2010Huber and Rupasinghe, 2009Shalini and Gupta, 2010Wolfe and Liu, 2003 M A N U S C R I P T …”

Effect of l-ascorbic acid addition on quality, polyphenolic compounds and antioxidant capacity of cloudy apple juices

“…Also Jaros et al [41] marked the content of polyphenolic compounds from different varieties of apples, in the range of 585-655 mg/L. According to Wolfe and Lui [47], the content of polyphenolic compounds in apple juices can affect the maturity and the variety of used fruit and to the greatest extent is shaped by the production process [7]. During the production of apple juice, a part of polyphenolic compounds undergo the process of enzymatic oxidation to quinones.…”

Byproducts of orange extraction: influence of different treatments in fiber composition and physical and chemical parameters

“…Citrus fiber is of high quality when compared to other forms of dietary fiber, due to the presence of associated bioactive compounds, such as flavonoids and other polyphenols, and carotenoids (Fernández-Ginés et al, 2003;Wolfe, Liu, 2003). Some studies have demonstrated the importance of the recovery of orange processing byproducts to obtain beneficial substances for the body, especially the gastrointestinal tract.…”