Effect of high hydrostatic pressure and thermal processing on cranberry juice

Cranberry is a native crop of North America. Many studies that have looked into the health benefits of consuming cranberry juice point to cranberry proanthocyanidins for the health promoting properties of the juice. Cranberry juice is usually sold as pasteurized juice; however, it is not known whether processing has any detrimental effect on the health promoting compounds. Anthocyanins, the major pigment compounds responsible for the color of cranberry juice are known to be unstable and sensitive to light, oxygen, high temperatures, and enzyme activity. Therefore, an alternative processing technology is needed to maintain color and nutraceuticals in cranberry juice. High hydrostatic pressure processing (HHPP) is a novel, non-thermal food processing method that destroys food borne bacteria while retaining thermally labile compounds. It has been shown the HHPP can be used to produce high quality orange juice. The objective of this research was to investigate the effect of thermal and high hydrostatic pressure processing on proanthocyanidins and anthocyanins in cranberry juice, immediately after processing and during storage, and to evaluate the impact of processing on the sensory attributes of the juice. During the study untreated cranberry juice was used as control. Proanthocyanidin content in the juice was analyzed by HPLC with UV/Fluorescence detection. Anthocyanin content was determined by pH differential method. Proanthocyanidin content was negatively affected by both pasteurization and high hydrostatic pressure treatments, and by storage time and temperature. Combination of higher pressure and longer time during HHPP was found to be the most detrimental process of for procyanidin retention. Anthocyanidin levels in the juice increased immediately after all treatments, but decreased in all samples during storage. However, no visual differences in color were observed after processing or during storage of the samples. Sensory evaluation of the processed and unprocessed juice samples showed no significant differences between the unprocessed and the processed samples.M.S.Includes bibliographical references (p. 75-80)