Investigation into the development of probiotic starter culture for industrial production of sauerkraut : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Auckland, New Zealand. EMBARGOED until 12 March 2028.

Abstract

While traditional fermentation methods continue to serve sauerkraut production, lack of defined, inherent starter cultures with predictable fermentation characteristics limits the continuous production of sauerkraut with consistent quality and safety. This study investigated to develop a probiotic starter culture for industrial production of sauerkraut. Organic white and mixed sauerkraut were prepared with added salt and allowed to ferment naturally at ambient temperature for seven weeks. The lactic acid bacteria (LAB), isolated from brine samples collected during fermentation were morphologically, physiologically and biochemically characterised and categorised based on their biochemical and physiological properties. Of the dominant subgroups of the dominant main groups, one representative LAB was selected and phylogenetically characterised using full length 16S rRNA gene sequencing. Based on phylogenetic analysis, three representative isolates (LA, LB and LP) were selected and evaluated for their in vitro probiotic potential and fermentation characteristics as mono- co- and mixed starter cultures using pasteurised organic cabbage juice fermented at 30 °C for 30 h. Altogether, 175 LAB isolates were obtained during natural fermentation of organic white and mixed sauerkrauts. The LA, LB and LP isolates had high 16S rRNA gene sequence identity (>99%) to Lactiplantibacillus argentoratensis DSM 16365, Levilactobacillus brevis ATCC 14869 and Lactiplantibacillus pentosus DSM 20314, respectively, and were dominant during natural fermentation of New Zealand organic sauerkraut. The three isolates exhibited significant in vitro probiotic potential, which requires further investigation for application in food fermentations and development of other probiotic products. The mixed culture (LA + LB + LP) was identified as the most promising starter culture based on the fermentation characteristics evaluated using cabbage juice as a laboratory model system. Further studies are recommended to evaluate the potential of using the mixed starter culture for fermentation of sauerkraut. To our knowledge, this is the first study on the identification and characterisation of inherent LAB in natural fermentation of New Zealand organic sauerkraut aimed at developing potential starter cultures with beneficial properties. The findings may be useful for potential development of inherent starter cultures for production of fermented cabbage and other vegetables.