Innovative fermentation methods reveal how pressed black cabbage, enriched with yeast or bacteria, delivers superior health benefits and flavor, opening new possibilities for functional foods.
Study: Innovative approaches for the fermentation of black cabbage with improved nutritional and health-promoting traits. Image Credit: Robyn-May / Shutterstock
In a recent article published in the journal LWT - Food Science and Technology, researchers investigated how controlled fermentation can improve the safety and nutritional value of black cabbage.
They found that fermentation significantly enhanced the antioxidant activity and polyphenol content of black cabbage, increased levels of health-supporting short-chain fatty acids (SCFAs) in yeast-fermented samples, introduced health-supporting compounds that varied with the starter used, and promoted the growth of beneficial gut bacteria, with all treatments boosting microbial abundance, but with only modest differences between unfermented and fermented samples in terms of overall microbiome shifts.
The study also found that yeast fermentation was associated with greater increases in the neurotransmitter GABA, which has been linked to blood pressure regulation and anti-depressive effects.
This study is notable as one of the first to systematically compare both lactic acid bacteria and yeast starters for black cabbage fermentation.
Background
Vegetables such as broccoli, cauliflower, and cabbage are rich in beneficial compounds, including glucosinolates, flavonoids, and polyphenols, which have been linked to lower risks of chronic illnesses, including neurodegeneration, cancer, and cardiovascular disease.
However, how these vegetables are processed is key in improving and preserving their beneficial compounds. Fermentation is a widely used method that preserves food, enhances its sensory and nutritional qualities, and makes it safer to consume. In cabbage, natural fermentation is driven by the lactic acid bacteria present in the plant, but this may lead to safety concerns, and the consistency of the fermented product cannot be easily controlled.
Attention has turned to the use of specific starter cultures, such as Lactiplantibacillus plantarum, to ensure improved, predictable, and consistent results. Studies have shown that starter-driven fermentation enhances the beneficial properties, polyphenol content, and antioxidant levels. However, the use of other starters, such as yeast, has not been explored. This study is the first to systematically compare the effects of both lactic acid bacteria and yeast starters for black cabbage fermentation.
About the study
Researchers applied controlled fermentation using selected bacteria and yeast starters to black cabbage to investigate how these treatments would affect its nutritional traits.
Fresh black cabbage leaves were sourced from a local Italian market before being washed and chopped into small pieces. The cabbage was then subjected to one of two fermentation methods, either immersion in a saltwater brine (80 g/L NaCl) or pressing the leaves with dry salt (40 g/kg) to release juices and start fermentation.
Two microbial strains were selected: the lactic acid bacterium Lactiplantibacillus plantarum TB 11-32 and the yeast Saccharomyces cerevisiae LI 180-7. These were cultured separately before being added to the cabbage to reach specific concentrations (~7 log CFU/g for bacteria, ~6 log CFU/g for yeast). The fermentation took place at room temperature in the dark for approximately 30 days. The mixture’s pH and salinity were monitored, and it was stirred every 10 days. Fermentation was considered complete if the pH was lower than 4.6.
After fermentation, samples were evaluated for microbial safety, chemical composition, and sensory traits. A sensory panel of 14 untrained participants assessed taste and texture using a scale from 0 (none) to 6 (intense). Samples were chewed and swallowed, with palate cleansing between tastings.
For microbial analysis, samples were diluted and cultured to assess the presence of beneficial microbes and check for harmful bacteria. Additionally, biochemical tests were done to measure changes in nutrients, polyphenols, and antioxidant activity using hydroalcoholic extracts from the fermented samples.
Findings
Fermentation of black cabbage using starter cultures (bacteria or yeast) significantly altered its chemical, sensory, and nutritional properties.
The pH dropped from 6.0 to around 4.0–4.1 by day 30, marking the end of fermentation, while salt levels stabilized at 70 g/L after 10 days in both brined and pressed samples. Pressed cabbage showed more texture loss, including softness and reduced fibrousness, but both preparations maintained food safety standards. Low levels of Enterobacteriaceae (~3 log CFU/g) were detected but were controlled by salt concentration and starter competition.
Starter cultures influenced taste and biochemical changes. Pressed cabbage fermented with yeast had lower bitterness and higher sweetness and umami than untreated samples. The organic acid content varied: lactic acid was highest in the bacterial samples, while the yeast-fermented samples showed more acetic acid.
Pressed samples also had higher counts of microbial lactic acid bacteria, supporting greater fermentation activity. Yeast growth was most pronounced in the yeast starter sample, while all treatments remained free of major pathogens.
Total phenolic content and antioxidant activity increased in all samples, with the yeast-fermented cabbage showing the largest gains: phenolic content rose 4.6 times, and antioxidant activity increased 3.4 times compared to unfermented cabbage. Fermentation enhanced the release of bioactive compounds from plant tissues. This effect was particularly marked in the pressed, yeast-fermented cabbage, while brined samples showed smaller increases.
LAB-fermented samples, on the other hand, showed increases in released phenolic compounds, which have potential cardiovascular health benefits.
Free amino acid content increased notably for both starters, especially for essential and bioactive amino acids. However, the yeast-fermented cabbage showed the highest overall increase, demonstrating a significant nutritional enhancement through fermentation. Specifically, the concentration of GABA (γ‑aminobutyric acid), a neurotransmitter associated with hypotensive and neuroprotective effects, rose significantly with both bacteria and yeast fermentation.
Distinct aroma profiles were observed: yeast fermentation produced more diverse and fruitier esters, while LAB fermentation resulted in higher levels of sulfur and other aroma-active compounds.
In vitro digestion and faecal fermentation experiments showed that all black cabbage samples, whether fermented or not, increased the abundance of beneficial gut bacteria compared to untreated faecal slurry. However, the differences between unfermented and fermented cabbage were modest for some bacterial groups. Yeast-fermented samples specifically promoted the production of short-chain fatty acids and related esters, compounds with potential benefits for gut health and irritable bowel syndrome, while LAB-fermented samples led to increased release of phenolic compounds that may help reduce oxidative stress and support cardiovascular health.
Conclusions
This study confirms that starter-driven fermentation can improve the safety, taste, and nutritional quality of black cabbage.
Both bacteria and yeast effectively reduced pH, enriched flavor, and enhanced the content of health-promoting compounds, including phenolics, antioxidants, and amino acids. Pressing cabbage before fermentation helped release more nutrients and improved microbial growth, particularly for beneficial bacteria and yeasts.
Using yeast showed the strongest improvements in taste, including lower bitterness and higher umami, as well as increased polyphenol content, antioxidant activity, and amino acid levels, suggesting that yeast starters can be highly effective. However, the study found that pressing with either good starter culture (LAB or yeast) offered optimal results, and both approaches showed distinct functional advantages. The findings suggest that fermentation using selected starters serves as a sustainable bio-preservation technique, producing a shelf-stable product without wastewater or by-products. Industrial-scale-up trials (processing over 300 kg batches) are underway, and a clinical trial is planned to further assess health impacts in humans.
These changes align with previous studies on sauerkraut and fermented vegetables, emphasizing the importance of fermentation methods and microbial strain selection.
Notably, no harmful microbes were found in any fermented product, demonstrating the safety of the process. All products met food safety standards, and the fermentation protocol offers environmental benefits by minimizing waste and allowing for year-round production.
Overall, pressed black cabbage fermented with yeast or LAB emerged as especially promising methods for developing flavorful and functionally enriched fermented vegetables, with yeast showing particular strength in sensory and nutritional enhancement, but both approaches contributing important health benefits.
Journal reference:
- Innovative approaches for the fermentation of black cabbage with improved nutritional and health-promoting traits. Tarantini, A., Mancini, L., Vacca, M., Celano, G., Romano, G., D’Amico, L., Cardinali, A., Bleve, G., De Angelis, M. LWT (2025). DOI: 10.1016/j.lwt.2025, https://www.sciencedirect.com/science/article/pii/S0023643825006450