Title : Ecology of traditional wooden fermentation vessels (Theki) and their role in spontaneous dairy fermentation
Abstract:
Traditional wooden fermentation vessels are increasingly recognized as functional microbial reservoirs; however, their role in spontaneous dairy fermentation remains insufficiently explored. This study provides a scientific basis for the traditional fermentation of dahi in a closed-neck wooden vessel (Theki) carved from Boehmeria rugulosa, which is widely used in the Himalayan region of India. The microbial diversity and functional role of indigenous microflora associated with the wooden vessel and fermented product were investigated. Microbial populations of Lactic Acid Bacteria (LAB) and yeasts were analyzed from both B. rugulosa wood and theki-fermented dahi. Comparable microbial profiles were observed between the wooden substrate and the fermented milk, confirming the transfer and persistence of resident microflora during fermentation.
A total of 33 microbial isolates were recovered, comprising 19 bacterial and 14 yeast strains. LAB populations (8.21 log CFU g⁻¹) were higher than yeast populations (7.29 log CFU g⁻¹). Dominant strains were identified using 16S rRNA gene sequencing and included Leuconostoc falkenbergense, Leuconostoc pseudomesenteroides, Leuconostoc mesenteroides, Bacillus paramycoides, and the yeast Naganishia adeliensis. These microorganisms constitute a stable indigenous consortium responsible for spontaneous milk fermentation without the requirement for external starter cultures or back-slopping. To evaluate the functional influence of this microbial ecosystem, dahi fermented naturally in the theki was compared with control dahi prepared in a glass container using an inoculated starter culture. The theki-fermented product exhibited improved physicochemical and sensory characteristics, including higher protein, mineral content, viscosity, and water-holding capacity, along with reduced syneresis and enhanced mouthfeel.
These findings demonstrate that Boehmeria rugulosa wooden vessels function as naturally sustained microbial ecosystems that regulate spontaneous milk fermentation and contribute to superior product quality. Understanding the microbial ecology of traditional fermentation vessels provides valuable insights for designing controlled fermentation systems and may support the development of novel processing approaches, including emerging technologies aimed at improving microbial functionality and product stability in fermented foods.
