Improving stability of color, total phenolics, flavonoids and ascorbic acid in cranberry juice cocktail via alternative processing and storage techniques.

摘要

Strong evidence suggests potent bioactivity in the phenolic and especially flavonoid fractions of cranberry, particularly anthocyanins (ACYs), flavonols (FLVs) and proanthocyanidins (PACs). Understanding how processing, packaging and storage effects these phytochemicals is crucial to maintaining cranberry nutritional value yet remains a considerable research gap.;Chromatographic methods were developed to monitor cranberry ACYs and FLVs. CJC was then subjected to combinations of conditions affecting oxidation, including light exposure, ascorbic acid fortification and oxygen exposure over thermal processing and storage to assess their effects and interactions on flavonoids and color stability. Subsequently, such treatments were applied to solutions of purified cranberry flavonoids to identify degradation products. Finally, CJC was bottled in oxygen barrier and standard packaging to see how well oxygen ingress could be limited and the treatments' effects in practical conditions.;Flavonoids, color and added ascorbic acid were indeed destabilized when exposed to oxygen. However fortification with ascorbic acid often destabilized flavonoids and color more so. The effects of nearly all treatments were attenuated by oxygen exposure. In practical packaging, oxygen barrier bottles only marginally reduced dissolved oxygen content. Light and ascorbic acid suppressed dissolved oxygen more thoroughly for bottled CJC, but apparently accomplished this by converting oxygen to more reactive species as these were most often destabilizing factors. Removal of oxygen before pasteurization proved a moderately effective treatment in limiting losses of color, flavonoids and ascorbic acid.;PACs were most stable, followed by FLVs and more unstable ACYs. Deglycosylation appears to be a major route of degradation for ACYs and FLV glycosides. Reactions between ascorbic acid and ACYs seem to be through products of ascorbic acid degradation and direct reaction. PACs or similar compounds seem to be created during the aging of CJC under some conditions.;This study investigated the impact of oxygen, light, ascorbic acid fortification and heat treatments on the stability of cranberry flavonoids (and color) in cranberry juice cocktail (CJC). Oxygen was expected to play a central directive role, so two innovative conditions were applied to limit oxygen levels during pasteurization and storage: pre-processing degassing -- a novel processing step for hot-filled juices -- and oxygen-impermeable plastic packaging.