Growth-Promoting Effect of Cava Lees on Lactic Acid Bacteria Strains: A Potential Revalorization Strategy of a Winery By-Product

Potential benefits of yeast Saccharomyces and their derivatives in dogs and cats: a review

Yeast Saccharomyces and its derivatives have been largely used in livestock and poultry nutrition for their potential positive impact on growth, performance, and general health. Originally included in animal diets as a source of protein, yeasts can also offer a wide range of by-products with interesting bioactive compounds that would confer uses beyond nutrition. Although its supplementation in livestock, poultry and even in humans is well documented, the available body of literature on the use of yeast and its derivatives in companion animals' food, mainly dogs and cats' diets, is still developing. Despite this, gut microbiota modulation, immune system enhancement or decreasing of potentially pathogenic microorganisms have been reported in pets when using these products, highlighting their possible role as probiotics, prebiotics, and postbiotics. This review attempts to provide the reader with a comprehensive on the effects of Saccharomyces and its derivatives in pets and the possible mechanisms that confer their functional properties.

Potential Prebiotic Effect of Cava Lees: Changes in Gut Microbiota

Lees are a winery by-product with a fiber-rich composition that could have a potential prebiotic effect on gut microbiota. Prebiotics cannot be digested by humans but can be used by bacteria found in the large intestine. To evaluate the potential prebiotic effect of lees, they were administered to Wistar rats for 14 days. Feces were collected daily, and DNA was extracted and analyzed by shot gun sequencing. The supplementation with lees did not affect weight, food intake, or water consumption of the studied rats. It was found that lees promoted the increase of relative abundance of probiotic bacteria belonging to the Lactobacillaceae family, as well as other potentially probiotic species such as Blautia hansenii, Roseburia intestinalis, and Ruminococcus obeum. Moreover, lees supplementation also reduced the abundance of certain pathogenic bacteria. In conclusion, lees can improve the presence of beneficial bacteria in the gastrointestinal tract and can be re-valorized as a new ingredient in food formulation.

Changes in the Volatile Profile of Wheat Sourdough Produced with the Addition of Cava Lees

The volatile fraction is of great importance for the organoleptic quality and consumer acceptance of bread. The use of sourdough improves the sensory profile of bread, as well as the addition of new ingredients to the fermentation. Cava lees are a sparkling wine by-product formed of dead microorganisms, tartaric acid, and other inorganic compounds, rich in antioxidant compounds as well as β-glucans and mannoproteins. The aim of this study was to evaluate the effect of different concentrations of Cava lees (0–2% w/w) on sourdough volatile compounds to re-valorize this by-product of the wine industry. Headspace solid-phase microextraction (HS-SPME) was optimized to study the volatile fractions of sourdoughs. The parameters selected were 60 °C, 15 min of equilibrium, and 30 min of extraction. It was found that the addition of Cava lees resulted in higher concentrations of volatile compounds (alcohols, acids, aldehydes, ketones and esters), with the highest values being reached with the 2% Cava lees. Moreover, Cava lees contributed to aroma due to the compounds usually found in sparkling wine, such as 1-butanol, octanoic acid, benzaldehyde and ethyl hexanoate.

By-Product Revalorization: Cava Lees Can Improve the Fermentation Process and Change the Volatile Profile of Bread

Wine lees are a by-product that represents a 25% of the total winery waste. Although lees are rich in antioxidant compounds and dietary fiber, they have no added value and are considered a residue. The aim of this study was to evaluate the effect of Cava lees (0 and 5% w/w) on microbial populations during sourdough and bread fermentation and the volatile fraction of the final bread. The results showed that 5% Cava lees promoted the growth of both lactic acid bacteria (LAB) and yeast in short fermentations (bread) but did not improve microbial growth in long fermentations (sourdough). Regarding volatile compounds, the addition of Cava lees increased the concentration of volatiles typically found in those products. Also, some compounds reported in sparkling wines were also identified in samples with Cava lees adsorbed on their surface. To sum up, the addition of Cava lees to sourdough and, especially, bread formulation may be a new strategy to revalorize such by-product.

Inhibition of Biogenic Amines Formation in Fermented Foods by the Addition of Cava Lees

Food safety can be compromised by some bioactive compounds such as biogenic amines that can be specially found in fermented foods due to the bacterial decarboxylation of some amino acids by fermentative or spoilage bacteria. Cava lees are a winery by-product rich in fiber and phenolic compounds and previous works have raised their revalorization from a food safety point of view. The aim of the current work was to investigate whether the use of cava lees can help to control biogenic amine formation in bread and fermented sausages. In bread, only very low levels of biogenic amines (putrescine, cadaverine, and/or spermidine) were found, whose content did not vary with the addition of different amounts of lees. However, the addition of lees in fermented sausages significantly reduced the formation of tyramine and cadaverine. In sausages spontaneously fermented and inoculated with Salmonella spp., the presence of cadaverine and putrescine diminished by 62 and 78%, respectively, due to the addition of cava lees. The addition of cava lees phenolic extract also showed an anti-aminogenic effect (21% for cadaverine and 40% for putrescine), although in a lesser extent than cava lees. Cava lees and their phenolic extract were shown to be an effective strategy to control the undesirable accumulation of high levels of biogenic amines during the production of fermented products.

Revalorization of Cava Lees to Improve the Safety of Fermented Sausages

The revalorization of food processing by-products not only reduces the environmental impact of their disposal, but also generates added economic value. Cava lees consist of inactive cells of Saccharomyces cerevisiae, and though regarded as a valueless winery by-product, they are rich in fiber and phenolic compounds. In this study, a challenge test was performed to assess the effect of cava lees and a phenolic extract (LPE) derived therefrom on the behaviour of technological microbiota (lactic acid bacteria used as a starter culture) and the foodborne pathogens Salmonella spp. and Listeria monocytogenes during the fermentation and ripening of pork sausages. Ten batches of fermented sausages were prepared with and without cava lees or the LPE, and with or without different strains of Latilactobacillus sakei (CTC494 or BAP110). The addition of cava lees reduced the pH values of the meat batter throughout the fermentation and ripening process. No growth-promoting effect on spontaneous lactic acid bacteria (LAB) or the starter culture was observed. In contrast, the presence of cava lees prevented the growth of the tested pathogens (Salmonella and L. monocytogenes), as did the starter culture, resulting in significantly lower counts compared to the control batch. In addition, the combination of cava lees with L. sakei CTC494 had a bactericidal effect on Salmonella. LPE supplementation did not affect the pH values or LAB counts but reduced the mean counts of Salmonella, which were 0.71 log10 lower than the control values at the end of the ripening. The LPE did not exert any additional effect to that of the starters applied alone. The revalorization of cava lees as a natural ingredient to improve the microbiological safety of fermented sausages is a feasible strategy that would promote a circular economy and benefit the environment.