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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION AND UTILIZATION OF THE GENETIC RESOURCES OF APPLES, GRAPES, AND TART CHERRIES

Location: Plant Genetic Resources

Title: Biodiversity of Total Phenolics, Antioxidant Capacity, and Juice Quality in Apple Cider Taxa

Authors
item Al-Turki, Saleh - COLORADO STATE UNIV
item Shahba, Mohamed - COLORADO STATE UNIV
item Forsline, Philip
item Stushnoff, Cecil - COLORADO STATE UNIV

Submitted to: Journal of Horticulture, Environment and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 10, 2008
Publication Date: December 30, 2008
Citation: Al-Turki, S., Shahba, M., Forsline, P.L., Stushnoff, C. 2008. Biodiversity of Total Phenolics, Antioxidant Capacity, and Juice Quality in Apple Cider Taxa. Journal of Horticulture, Environment and Biotechnology. 49(6):409-417.

Interpretive Summary: Apple antioxidants may play an important role in human health by providing protection against free radicals that can react and damage a wide range of biological molecules, including nucleic acids, lipids and proteins. While fresh apple juice is the main product of processed apples, little information is available about differences in the multiple varieties that consumers are offered nor about the impact of pasteurization on apple juice antioxidant properties. The objectives of this study were to document the differences among a broad range of apples in the world’s most diverse genetic collection of apples at the USDA-ARS Geneva, NY. We also defined the effect of pasteurization on total phenolic content, antioxidant capacity and juice quality. Juice from the fruit of 21 familiar apple varieties as well as juice from a broad range of wild apples was extracted and divided into two equal portions. One portion was immediately pasteurized in a water bath for 30 min. at 75o C. Non-pasteurized and pasteurized samples were tested for total phenolics. Nine common varieties and samples from 2 wild apple species were selected for further investigations. Juice browning, sugar content, acidity, antioxidant capacity and total phenolics were determined for both non-pasteurized and pasteurized juice samples. Pasteurization had no effect on totals phenolics but had a significant effect on antioxidant activity. Also there was a significant difference among common varieties and wild apple species in both cases. Pasteurization decreased juice browning only for one of the wild species representatives and there was no effect on other samples. Pasteurization had no effect on sugar content nor on juice acidity. There was no relationship between total phenolics content and juice browning, total sugars or acidity. This study advances the understanding of apple biodiversity on total phenolics and antioxidant capacity of apple juices, their quality, and the relationship among them.

Technical Abstract: Apples are known to contain antioxidants that may play an important role in human health by providing protection against reactive free radicals affecting a wide range of biological molecules including nucleic acids, lipids, and proteins. While fresh apple juice is a main product of processed apples, there is little information on cultivar differences or on the impact of pasteurization on apple juice antioxidant properties. The objectives of this study were to document differences among apple species and cultivars in antioxidant properties and to define the effect of pasteurization on total phenolics content, antixodant capacity, and juice quality. Juice from the fruit of 21 apple cultivars (Malus domestica) and eleven apple species (M. sieversii) was extracted and divided into two equal portions. One portion was immediately pasteurized in a water bath for 30 min at 75 degrees Celsius. Non-pasteurized and pasteurized samples were tested for total phenolics content using Folin-Ciocalteu reagent. Depending on their total phenolics content, these were divided into eleven similar groups using Duncan’s multiple range test. Nine cultivars and two species representing the eleven groups were selected for further investigations. Juice browning, soluble solids content, pH, and total phenolics content were determined for both non-pasteurized and pasteurized juice samples. Antioxidant radical scavenging capacity was measured with a 2,2’-axino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) assay. In non-pasteurized juice, total phenolics content ranged from 107.9 to 1,5550 mg L -1 and from 127.1 to 2,212.3 mg L -1 in pasteurized juice. ABTS radical scavenging capacity ranged from 16.2 to 63.3 mM trolox equivalent antioxidant capacity in non-pasteurized juice from 11.5 to 41.3 mM in pasteurized juice. Pasteurization had no effect on total phenolics content, but had a significant effect on antioxidant capacity. There was a significant difference among cultivars and species in both cases. Pasteurization decreased juice browning only for M. sieversii 4002.a and there was no effect on other taxa. Pasteurization had no effect on soluble solids content nor on juice pH. The results suggested an approximate 92 and 73% relationship between total phenolics and ABTS radical scavenging in non-pasteurized and pasteurized juices, respectively. There was no relationship between total phenolics content and juice browning, total soluble solids content, or pH. This study advances the understanding of the biodiversity of total phenolics components and antioxicant capacity of apple juices, their quality, and the relationship among them.

Last Modified: 4/18/2014