Abstract:

A comparative analysis of the effect of three different sterilization methods, namely pasteurization, ultra high
temperature treatment (UHT) and ultra high hydrostatic pressure (UHHP), on the microbial load, quality and aroma
composition of mulberry juice was carried out in the present investigation. The results indicated mulberry juice met the
requirement of commercial sterilization according to the Chinese national standard GB 19297—2003 after being sterilized
by the above three methods, especially by UHT treatment, which achieved complete microbial inactivation. Compared
with the blank group, soluble solids and total sugar contents significantly decreased (P < 0.05) after pasteurization and
UHT treatment. UHHP treatment had the largest impact on the content of anthocyanins. The content of total phenol
and flavonoids, and antioxidant capacity declined to different extents after different sterilization treatments, and UHHP
treatment changed the least. As indicated by solid-phase micro-extraction (SPME) coupled with gas chromatography-mass
spectrometry (GC-MS), 52, 42, 44 and 49 volatile aroma components were identified in the blank control and mulberry
juice subjected to pasteurization, UHT and UHHP treatments, respectively. UHHP treatment was the most close to the blank
group as far as the main aroma components were concerned. In general, UHHP technology has good sterilization efficiency
while effectively maintaining the quality of mulberry juice.

Key words: mulberry juice, pasteurization, ultra high temperature treated (UHT), ultra high hydrostatic pressure (UHHP)