Influence of industrial blanching, cutting, and freezing treatments on in vitro gastrointestinal digestion stability of orange (Citrus sinensis L.) and lemon (Citrus limon L.) peel polyphenols

Abstract

BACKGROUNDCitrus peels, which are often discarded as waste in the food‐processing industry, are rich sources of polyphenols. The aim of the current study was to investigate the influence of an industrial freezing process along with blanching and cutting pretreatments on the in vitro gastrointestinal digestion stability of orange (Citrus sinensis L.) and lemon (Citrus limon L.) peel polyphenols. The major polyphenols were identified and quantified with ultra‐performance liquid chromatography‐electrospray tandem mass spectrometry (UPLC‐ESI‐MS/MS) and high performance liquid chromatography‐photodiode array detector (HPLC‐PDA), respectively.RESULTSThe results revealed that hesperidin and chlorogenic acid were the predominant flavonoid and phenolic acids in orange peels whereas, for lemon peels, eriocitrin and caffeic acid were the dominant flavonoid and phenolic acids, respectively. Blanching pretreatment enhanced the levels of major flavonoids in orange and lemon peels (by 39–82% and 54–146%, respectively) (P < 0.05) after in vitro gastrointestinal digestion. On the other hand, the application of cutting treatment after blanching significantly reduced the levels of flavonoids (23–62%) (P < 0.05); however, there was no statistically significant difference between the phenolic acid levels of cut and uncut citrus peels. Overall, the bioaccessibility of individual flavonoids and phenolic acids from frozen orange peels was generally slightly lower than that of untreated peels (9–34% and 9–49%, respectively). Nevertheless, frozen lemon peels contained higher bioaccessible flavonoids and phenolic acids in comparison with untreated peels (40–172% and 32–98%, respectively).CONCLUSIONThese results suggest that industrial freezing steps could largely preserve the bioaccessibility of polyphenols in orange and lemon peels. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bioaccessibility of Carotenoids and Polyphenols in Organic Butternut Squash (Cucurbita moschata): Impact of Industrial Freezing Process

“…These modifications in the matrix may enhance the release of flavonoids during in vitro gastrointestinal digestion. The positive impact of the industrial freezing process on the bioaccessibility of flavonoids also has been observed in previous studies involving strawberry [16] and lemon peel [9].…”

“…The disposal of such waste products in the industry not only has the potential to create adverse environmental impacts but also poses a significant cost for the industry. On the other hand, multiple studies have indicated that some industrial food wastes can be utilized as sources of bioactive compounds including carotenoids and polyphenols [9][10][11]. Moreover, pumpkin seed, belonging to the same family as squash, may be consumed fresh or roasted as appetizers, and is quite popular in Türkiye with the production of 42.000 tons per year [12,13].…”