Dairy by-product offers natural preserving alternative to chlorine
preserver, suggests new research, as the industry looks to
alternatives to chlorine solutions for preserving fresh-cut
vegetables.
"These results suggest that whey permeate could be a promising alternative to chlorine for sanitising fresh-cut vegetables," said the researchers from Dublin Institute of Technology.
Fresh-cut fruits and vegetables are a rapidly growing segment of the market, and chlorine solutions are widely used by the industry to sanitise and prolong the shelf-life. But concerns about the potential formation of carcinogens from chlorine usage has prompted some to investigate alternative sources including essential oils and irradiation.
The new research, published in the journal Innovative Food Science and Emerging Technologies (Vol. 7, pp. 112-123), looks at the use of whey permeate (WP) solutions of varying concentrations on the markers of preservation, such as colour and textural changes, microbiological concentrations and nutritional content (vitamin C and carotenoid).
Three concentrations of WP solutions were prepared: 0.5 per cent (pH 3.84), 1.5 per cent (pH 3.53), and 3 per cent (pH 3.45). The whey permeate was provided by Glanbia, Ireland. A chlorine solution (120 ppm, pH 8) was also prepared for comparison. Iceberg lettuce and carrots were used as test vegetables.
The microbial counts for 3 per cent WP were similar or better than the chlorine solution, but the less concentrated WP solutions were found to result in higher microbial counts. However at the end of storage (10 days) the microbial counts for the 0.5 and 1.5 per cent WP solutions was still lower than the recommended safety levels for fresh-cut vegetables (100m CFU per grams).
The sensory analysis showed that both the 3 per cent WP and the chlorine solution produced less acceptable products due to slight blanching of the vegetables. The use of the higher concentration WP also reduced the vitamin C and carotenoid level more than the 0.5 and 1.5 per cent WP washes.
"Whey permeate showed good antimicrobial activity when used as a wash treatment for sliced carrots and fresh-cut lettuce. The concentration of the WP was an important factor in the control of microbial growth," wrote lead author Anabelen Martin-Diana.
This anti-microbial activity is most likely due to the pH of the wash solutions, suggested the researchers, or perhaps due to the presence of bio-active peptides.
"These results suggest that three per cent WP is a promising formula although further investigations are needed in order to optimise in terms of shelf-life, nutritional value, safety and quality," concluded the researchers.
