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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Publications at this Location » Publication #283642
Title: Storage stability of sterilized liquid extracts from pomegranate peel

Author
item QU, WENJUAN - Jiangsu University
item Breksa, Andrew
item Pan, Zhongli
item MA, HAILE - Jiangsu University
item McHugh, Tara

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2012
Publication Date: 7/3/2012
Citation: Qu, W., Breksa III, A.P., Pan, Z., Ma, H., Mchugh, T.H. 2012. Storage stability of sterilized liquid extracts from pomegranate peel . Journal of Food Science. 77(7):C765-C772. DOI: 10.1111/j.1750-3841.2012.02779.x.

Interpretive Summary: Pomegranate marc, a byproduct of commercial juice production, has shown promise as a starting material for the recovery of health promoting phenolic compounds. The stability of aqueous extracts prepared from pomegranate marc was evaluated in preparation to directly using these extracts as nutraceuticals or food additives. The liquid extracts were produced under extraction conditions of 25 ºC, water to peel ratio of 50:1 (w/w) for 2 min, and then sterilized at 121 ºC for 10 s. Storage conditions tested included three different pH values (3.5, 5.0, and 7.0) and two packaging methods (no light and exposure to light). The results showed that both pH value and packaging method significantly influenced the industrial (pH, total soluble solid content, and clarity), and color characteristics of the extracts. The high pH had a negative effect on spectral and antioxidant characteristics. Therefore, the recommended storage conditions are low pH and with dark packaging to maintain the high storage stability.

Technical Abstract: Pomegranate marc, a byproduct of commercial juice production, has shown promise as a starting material for the recovery of health promoting phenolic compounds. The stability of aqueous extracts prepared from pomegranate marc was evaluated in preparation to directly using these extracts as nutraceuticals or food additives. The liquid extracts were produced under extraction conditions of 25 ºC, water to peel ratio of 50:1 (w/w) for 2 min, and then sterilized at 121 ºC for 10 s. Storage conditions tested included three different pH values (3.5, 5.0, and 7.0) and two packaging methods (no light and exposure to light). The extracts were evaluated for industrial (pH, total soluble solid content, and clarity), color, spectral and antioxidant characteristics over 180 days. The results showed that both pH value and packaging method significantly influenced the industrial and color characteristics of the extracts. The high pH had a negative effect on spectral and antioxidant characteristics. Therefore, the recommended storage conditions are low pH and with dark packaging to maintain the high storage stability. After 180 days of storage, extracts stored at low pH 3.5 in dark packaging still retained 67% and 58% of their total soluble phenolic concentration and antioxidant activity, compared to 61% and 43% of phenolic concentration and antioxidant activity of high pH 7.0 samples, and were found to be composed of high concentrations of punicalagins A and B, gallic, and ellagic acids.