Bacteriocin production by lactic acid bacteria using ice cream by-product as the fermentation substrate

Authors: Miller, Amanda; Renye, John; Oest, Adam; LIANG, CHEN - Oak Ridge Institute For Science And Education (ORISE); Garcia, Rafael; Plumier, Benjamin; Tomasula, Peggy

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2023
Publication Date: 6/1/2024
Citation: Miller, A.L., Renye Jr, J.A., Oest, A.M., Liang, C., Garcia, R.A., Plumier, B.M., Tomasula, M.M. 2024. Bacteriocin production by lactic acid bacteria using ice cream by-product as the fermentation substrate. Journal of Dairy Science. https://doi.org/10.3168/jds.2023-24249.
DOI: https://doi.org/10.3168/jds.2023-24249

Interpretive Summary: Ice cream manufacture commonly results in the accumulation of wasted product which contains valuable food-grade quality components, including fat, carbohydrates, and protein. Companies are unable to dispose of this material within landfills due to melting and potential environmental concerns, and removal would be a significant financial burden for the industry. Currently the waste has been used for animal feed, soil amendment or energy production via anaerobic fermentation; but all these outlets result in the loss valuable components which could be recaptured and upcycled for production of new foods. Methods have been developed for the extraction of food grade butter fat from wasted ice cream, which results in the generation of a watery by-product rich in fermentable carbohydrates. This study investigated the potential for using fermentation with dairy starter cultures to generate natural antimicrobial peptides with can be used in the formation of animal feed, with the intention of preventing infections and reducing the need for antibiotics.

Technical Abstract: Ice cream manufacture commonly results in the accumulation of wasted product which contains valuable food-grade quality components, including fat, carbohydrates, and protein. Methods have been developed for recovering the fat from this waste stream, but this results in the generation of a by-product rich in fermentable carbohydrates. This study aimed to investigate the potential for using this by-product as a fermentation substrate for production of antimicrobial peptides, called bacteriocins, by dairy starter cultures. Results showed that Streptococcus thermophilus B59671 and Lactococcus lactis 11454 produced the broad spectrum bacteriocins thermophilin 110 and nisin respectively when the fermentation substrate was melted ice cream, or a by-product generated when fat was extracted using a modified butter churning technique. Bacteriocin production varied depending on the brand and variety of vanilla ice cream used in this study, with thermophilin 110 concentrations ranging from 90 AU mL-1 to 960 AU mL-1; and nisin concentrations varying between 200 AU mL-1 to 360 AU mL-1. When an alternate enzyme-assisted fat extraction technique was utilized, S. thermophilus growth was significantly impaired within the resulting by-product, and thermophilin 110 production was not observed. L. lactis was still able to grow in this by-product, still no antimicrobial activity was observed. Results from this study suggest the by-product generated when using the churning technique is a better choice to use as a base medium for future studies to optimize bacteriocin production.