UC Davis

Food fermentations are an ancient practice, integral to many global cultural and culinary practices. Traditional fermented foods (FF) have developed from access to unique raw materials, with distinctive properties of aroma, texture, appearance, and ingredients. FFs have long been relied on for their ability to transform raw substrates into a safe, nutritious, and flavorful final product. While documentation of FF dates back to ancient civilizations, our understanding of these foods was greatly expanded in the seventeenth century when early microbiologists determined this transformation process to be controlled by microorganisms. This understanding led to the commercial production of FFs, such as sauerkraut and pickled cucumbers, in large quantities, thus establishing them as a dietary staple. The prevalence of more highly processed and convenience foods in the diet of Western countries led to decreased interest in and consumption of FFs. However, recent consumer demand for FFs has led to a revival of such products which has coincided with a growing movement towards artisanal and locally sourced food production. This research aims to improve understanding of this recent trend within the U.S. with the main objectives: 1) to evaluate consumer familiarity with consumption patterns, and perceptions of FF; 2) determine frequency and type of fermentations conducted in U.S. households; and 3) determine replicability of a novel cabbage-based fermentation.To evaluate consumer perceptions and consumption patterns of FFs, an online public survey was developed. This survey assessed participants’ recognition of different types of FFs, the most frequently consumed categories, and gained insight into motivations for consumption.

A total of 751 participants completed this survey in 2022; survey questions are listed in Appendix 1, with responses for general questions and demographic questions in Appendix 2 and Appendix 4, respectively. From a list of provided FFs, only 7% (n=55) of participants correctly identified all as fermented with yogurt the most frequently identified by all participants. The least frequently identified FF was escabeche, by 15.71% (n=118) of participants. Of the provided categories, participants reported consuming fermented cereal grains (46.17%; n=307), fruits and vegetables (42.26%; n=281), dairy (39.70%; n=264), meat (30.68%; n=204), and rice or soybean products (37.60%; n=250). Approximately half (50.68%; n=337) of participants reported taste of FFs as the primary motivator for consumption while health benefits and cultural reasons were selected by 35.54% (n=235) and 12.03% (n=80) of participants, respectively. The most frequently associated health benefits of fermented foods were “improved gut microbiome” (77.14%; n=513), “digestive benefits” (76.39%; n=508), and “probiotic” (68.87%; n=458). Responses to matched questions about both non-alcoholic fermented foods and fermented fruits and vegetables did not vary, suggesting consumers do not differentiate expectations and motivations for different categories of FFs.A second portion of this survey assessed if people in the U.S. ferment fruits and vegetables at home. All survey questions are listed in Appendix 1 with participant responses of each question in Appendix 3. Of the 751 total participants, 49.20% (n=367) reported fermenting fruits and vegetables at home. When asked what fruits or vegetables they ferment at home, most frequently reported from free responses were cabbage (53.30%; n=202), cucumbers (23.22%; n=88), alliums (14.25%; n=54), carrots (13.72%; n=52), and peppers (12.66%; n=48). Participants reported using recipe style books (46.32%; n=170) most frequently as a source of information on fermenting fruits or vegetables. Participants expressed interest in learning more about the fermentation of cucumbers (37.60%; n=138), berries (29.16%; n=107), peppers (28.61%; n=105), olives (28.33%; n=104), and cabbage (26.43%; n=97). Due to this interest in home fermentations, a recipe for a small-batch fermentation was developed containing red cabbage, carrots, and ginger. Two salt concentrations, 2% and 3% NaCl, were evaluated at 22°C in a laboratory environment. To assess environmental influence on the fermentation repeatability, the 3% NaCl recipe was replicated in five household kitchens near Davis, CA. Brine pH and salinity measurements were collected across a 21-day fermentation period for laboratory ferments. Microbial growth was measured through culturing of fungal and lactic acid bacteria, evaluated in combination with V4-16S rRNA gene sequencing. By day 2 of the fermentation, all treatments achieved a pH of below 4.6. While observed pH reductions were consistent across fermentations, salinity had an effect on microbial population dynamics. In the 3% NaCl lab fermentation, statistically higher counts of LAB were detected on days 1, 2, 3, 4, 5 and 7. Alpha diversity of fermentations decreased during fermentation for all treatments yet was higher for the 2% NaCl fermentation compared to those with 3% NaCl, with a greater abundance of Enterobacterales and lower abundance of Lactobacillales across all measured time points. Leuconostoc was the most abundant genus by day 2 of the laboratory-based fermentations. However, all fermentations, including those conducted in households, had differing Leuconostoc amplicon sequencing variants (ASV) represented. These results indicate that while differences in salinity and fermentation environment influenced the final fermentation microbial population, all fermentation treatments reached the key critical control point of a pH decline to below 4.6.