Natural glycolipids inhibits certain yeasts and lactic acid bacteria pertinent to the spoilage of shelf stable beverages
Yupawadee Galasong, Jonathan H. Sogin, Randy W. Worobo
Abstract
The public health concern around artificial preservatives in food and beverage has contributed to the rising demand for clean-label products, which inevitably require changes in formulation and processing of existing products. Natural glycolipids (NG), derived from Dacryopinax spathularia, is a novel naturally derived preservative shown to be highly inhibitory against spoilage yeasts, Gram-positive bacteria, and to a lesser extent molds. The inhibitory effect of NG against major spoilage microorganisms was determined in acidified beverages (iced tea and sparkling beverage containing fruit juice). Three-strain suspensions of yeasts (Saccharomyces cerevisiae, Zygosaccharomyces bailii and Candida parapsilosis), bacteria (Lactiplantibacillus plantarum, Lactococcus lactis and Gluconacetobacter liquefaciens) and fungal spores (Aspergillus brasiliensis, Byssochlamys nivea and Penicillium roqueforti) were inoculated (100 CFU/mL per species) in commercial beverages. NG was added to beverages at low concentrations ranging from 5 to 15 ppm. Additionally, the combination of NG and dimethyl dicarbonate (DMDC) was tested in the still beverage. The efficacies of NG and NG + DMDC were compared to treatment with 250 ppm sodium benzoate (SB) as determined by log reduction after beverage samples were maintained for 12 weeks at ambient temperature. The applied NG concentrations were lethal to lactic acid bacteria (LAB) and yeasts, thus capable of protecting the beverages from microbiological spoilage for 12 weeks; NG was more effective than SB, which resulted in microbial growth comparable to the control (untreated) samples. NG exhibited mildly microstatic properties against acetic acid bacteria (AAB) and fungal spores. While NG + DMDC treatments improved the inhibition of yeasts and bacteria, there was no observable effect on fungal spores. This study demonstrated that NG can be used alone or combined with DMDC to prevent spoilage in beverages maintained at ambient temperature.