Purpose: The objectives of this study were to determine the antiviral effects of GSE at 37°C in (1) apple juice (AJ) and 2% milk as model food systems; and (2) under simulated gastrointestinal conditions against FCV-F9 and MNV-1.
Methods: FCV-F9 and MNV-1 at ~5 log PFU/ml were treated with GSE at 2, 4 or 8 mg/ml prepared in apple juice (AJ; pH 3.6), 2% milk, simulated gastric fluid (SGF; pH 1.5) or simulated intestinal fluid (SIF; pH 7.5), and AJ, 2% milk, SGF, SIF, malic acid (pH 1.5 and 3.0) and phosphate buffered saline (pH 7.2) over 24 h at 37°C. Virus infectivity of triplicate treatments was evaluated using plaque assays in duplicate and data were statistically analyzed.
Results: GSE at 1 mg/ml in AJ reduced FCV-F9 to undetectable levels after 5 min, while 4 mg/ml GSE in milk reduced FCV-F9 by 1.07 ± 0.03 log PFU/ml after 24 h. GSE at 1 mg/ml in AJ reduced MNV-1 to undetectable levels after 1 h, while 1, 2 and 4 mg/ml GSE in milk all reduced MNV-1 by merely 0.3 log PFU/ml after 24 h. Both viruses did not survive in SGF after 1 h. GSE at 1 mg/ml in SIF reduced FCV-F9 to undetectable levels after 1 h and MNV-1 by 1.03 ± 0.04 log PFU/ml after 1 h.
Significance: Reduced antiviral activity of GSE was observed in milk compared to apple juice. These results indicate that time-released GSE encapsulation may be needed for use as antivirals or application in food systems to cause optimal foodborne viral reduction.