Effects of high hydrostatic pressure and thermal processing on bioactive compounds, antioxidant activity, and volatile profile of mulberry juice

Abstract

The aim of this study was to investigate the effects of high hydrostatic pressure and thermal processing on microbiological quality, bioactive compounds, antioxidant activity, and volatile profile of mulberry juice. High hydrostatic pressure processing at 500 MPa for 10 min reduced the total viable count from 4.38 log cfu/ml to nondetectable level and completely inactivated yeasts and molds in raw mulberry juice, ensuring the microbiological safety as thermal processing at 85 ℃ for 15 min. High hydrostatic pressure processing maintained significantly (p < 0.05) higher contents of total phenolic, total flavonoid and resveratrol, and antioxidant activity of mulberry juice than thermal processing. The main volatile compounds of mulberry juice were aldehydes, alcohols, and ketones. High hydrostatic pressure processing enhanced the volatile compound concentrations of mulberry juice while thermal processing reduced them in comparison with the control. These results suggested that high hydrostatic pressure processing could be an alternative to conventional thermal processing for production of high-quality mulberry juice.

Physicochemical properties and bioactive compounds of fermented pomegranate juice as affected by high-pressure processing and thermal treatment

“…Similar results were obtained by others. [5,7] Wang et al [7] found that Y&M were not detected in mulberry juice treated at 300 MPa/10 min, and the minimum holding times sufficient to produce mulberry juice with no detectable TAB was located at 500 MPa/10 min. According to Chen et al [5] , the Y&M were not detected in cloudy pomegranate juice, treated at 400 MPa/5 min, while the TAB were detected at 1.52 log 10 CFU/mL.…”

“…The FPJ was processed using the method described by Wang et al [7] with slight modifications. For the HPP treatments, 40 mL of FPJ was poured into polyethylene/nylon vacuum bags (Huadun Plastics Co., Chengdu, China).…”

“…The total flavonoid content was determined using the modified aluminum chloride colorimetric method described by Wang et al [7] A 0.5 mL volume of FPJ (previously diluted 10-fold with distilled water) was mixed with 0.15 mL of 5% NaNO 2 . Following incubation for 6 min, 0.15 mL of 10% AlCl 3 was added to the mixture.…”

“…The volatile compounds in the FPJ were analyzed using a headspace solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS) system as described by Wang et al [7] with some modifications. The GC-MS QP2010plus, (Shimadzu USA MANUFACTURING, Inc., Kyoto, Japan) was used.…”

“…However, this method significantly depreciates the quality of the juice by causing the loss of nutritional components, and inducing changes in color, flavor, and texture due to their heat sensitivity. [5][6][7] Subjecting pomegranate juice to TP might cause the degradation of anthocyanins, leading to a brownish color during processing and storage. [8] The color changes substantially affect consumer behavior and result in a loss of the marketability of processed pomegranate products.…”