Effect of fermentation on the content of bioactive compounds in tofu-type products

A glimpse into plant-based fermented products alternative to animal based products: Formulation, processing, health benefits

Fermented foods and beverages are increasingly being included in the diets of people around the world, as they significantly contribute to flavor and interest in nutrition and food consumption. Plant sources, like cereals and pulses, are employed to produce vegan fermented foods that are either commercially available or the subject of ongoing scientific investigation. In addition, the inclination towards nutritionally healthy, natural, and clean-label products amongst consumers has encouraged the development of vegan fermented products alternative to animal-based products for industrial-scale production. However, as the vegan diet is more restrictive than the vegetarian diet, manufacturing food products for vegans presents a significant problem due to the limited availability of many raw materials. So further research is required on this topic. This paper aims to review the formulation, quality, microbial resources, health benefits, and safety of foods that can be categorised as vegan fermented foods and beverages.

Effects of fermentation time on the bioactive constituents of Kinema, a traditional fermented food of Nepal

Kinema is a traditional food prepared by the natural fermentation of cooked soybeans. The fermented Kinema is known to have several bioactive constituents, however, only limited reports on the effect of fermentation time on the bioactivity of Kinema are available. Therefore, in this work, changes in phenolics content and radical scavenging activity of Kinema at different fermentation times were explored. Furthermore, the optimum fermentation time for maximum bioactivities (total phenolic content, total flavonoid content, and DPPH radical scavenging activity) was determined using one-factor response surface methodology. The numerical optimization suggested an optimum fermentation time of 29.6 h with significantly higher total phenolics and flavonoid contents of 62.84 ± 0.89 mg GAEs/g dry extract, 45.41 ± 0.57 mg QEs/g dry extract, respectively (p < 0.05) compared to traditionally fermented Kinema. Similarly, the IC₅₀ concentration for DPPH radical scavenging activity of 1.78 ± 0.01 mg dry extract/mL, was significantly lower than those for traditionally prepared Kinema (p < 0.05). Moreover, optimized Kinema had significantly higher overall sensory scores compared to the traditional sample. The results suggested that fermentation time affects the amount of bioactive constituents of Kinema. Further studies are needed to explore the changes in the type of phenolic and flavonoid compounds.

Effect of Coagulant and Treatment Conditions on the Gelation and Textural Properties of Acidic Whey Tofu

This study aimed to investigate the properties of acidic whey tofu gelatin generated from two acidic whey coagulants by pure fermentation of Lactiplantibacillus paracasei and L. plantarum, as well as the characteristics of acidic whey tofu. The optimal holding temperature and the amount of coagulants added were determined based on the pH, water-holding capacity, texture, microstructure, and rheological properties of tofu gelation. Then, the differences in quality between tofu produced by pure bacterial fermentation and by natural fermentation were investigated under optimal tofu gelatin preparation conditions. The tofu gelatin presented the best texture at 37 °C with a 10% addition of coagulants fermented by both L. paracasei and L. plantarum. Under these conditions, the coagulant produced by the fermentation of L. plantarum resulted in a shorter formation time and stronger tofu gelatin compared with that produced from L. paracasei. Tofu produced by the fermentation of L. paracasei had higher pH, less hardness, and a rougher network structure, whereas tofu produced by the fermentation of L. plantarum was closer to tofu produced by natural fermentation in terms of pH, texture, rheology, and microstructure.

High-Pressure Homogenization and Biocontrol Agent as Innovative Approaches Increase Shelf Life and Functionality of Carrot Juice

Recently, application of high-pressure homogenization (HPH) treatments has been widely studied to improve shelf life and rheological and functional properties of vegetable and fruit juices. Another approach that has drawn the attention of researchers is the use of biocontrol cultures. Nevertheless, no data on their possible combined effect on fruit juices shelf life and functionality have been published yet. In this work, the microbial, organoleptic, and technological stability of extremely perishable carrot juice and its functionality were monitored for 12 and 7 days (stored at 4 and 10 °C, respectively) upon HPH treatment alone or in combination with a fermentation step using the biocontrol agent L. lactis LBG2. HPH treatment at 150 MPa for three passes followed by fermentation with L. lactis LBG2 extended the microbiological shelf life of the products of at least three and seven days when stored at 10 °C and 4 °C, respectively, compared to untreated or only HPH-treated samples. Moreover, the combined treatments determined a higher stability of pH and color values, and a better retention of β-carotene and lutein throughout the shelf-life period when compared to unfermented samples. Eventually, use of combined HPH and LBG2 resulted in the production of compounds having positive sensory impact on carrot juice.

A new style of fermented tofu by Lactobacillus casei combined with salt coagulant

This research provided a new way to improve the quality of tofu using lactic acid bacteria combined with salt coagulants. In this study, the effect of Lactobacillus casei (L. casei) combined with salt coagulants (MgCl₂, MgSO₄, CaCl₂, CaSO₄) on the yield, water-holding capacity (WHC), texture, sensory factors, microstructure and flavour were analysed to evaluate the quality characteristics of fermented tofu. The results showed that the yield of tofu was significantly increased by the fermentation of L. casei (24.75-31.26%). There was no significant difference in the WHC of the tofu, and the value range of WHC was 77.32-80.52%. Fermentation increased the hardness of the tofu and made the tofu structure uniform. In L. casei + MgSO₄ tofu, 10 flavour compounds were detected, and the relative content (54.29%) of the four main flavour compounds was highest. L. casei + MgSO₄ had the highest sensory value (23.26). The fermentation of L. casei combined with salt coagulants significantly improved the quality characteristics of tofu.

How Fermentation Affects the Antioxidant Properties of Cereals and Legumes

The major role of antioxidant compounds in preserving food shelf life, as well as providing health promoting benefits, combined with the increasing concern towards synthetic antioxidants, has led the scientific community to focus on natural antioxidants present in food matrices or resulting from microbial metabolism during fermentation. This review aims at providing a comprehensive overview of the effect of fermentation on the antioxidant compounds of vegetables, with emphasis on cereals- and legumes- derived foods. Polyphenols are the main natural antioxidants in food. However, they are often bound to cell wall, glycosylated, or in polymeric forms, which affect their bioaccessibility, yet several metabolic activities are involved in their release or conversion in more active forms. In some cases, the antioxidant properties in vitro, were also confirmed during in vivo studies. Similarly, bioactive peptides resulted from bacterial and fungal proteolysis, were also found to have ex vivo protective effect against oxidation. Fermentation also influenced the bioaccessibility of other compounds, such as vitamins and exopolysaccharides, enabling a further improvement of antioxidant activity in vitro and in vivo. The ability of fermentation to improve food antioxidant properties strictly relies on the metabolic activities of the starter used, and to further demonstrate its potential, more in vivo studies should be carried out.

Volatile Molecule Profiles and Anti-Listeria monocytogenes Activity of Nisin Producers Lactococcus lactis Strains in Vegetable Drinks

This work aimed to evaluate the potential of 15 nisin producing Lactococcus lactis strains, isolated from dairy products, for the fermentation of soymilk and carrot juice. In particular, the acidification and the production of nisin in the food matrices were recorded. Moreover, three strains (LBG2, FBG1P, and 3LC39), that showed the most promising results were further scrutinized for their anti-Listeria monocytogenes activity and volatile molecules profile during fermentation of soymilk and carrot juice. Lactococcus lactis strains LBG2, FBG1P, and 3LC39 resulted the most interesting ones, showing rapid growth and acidification on both food matrices. The higher amounts of nisin were detected in soymilk samples fermented by the strain LBG2 after 24 and 48 h (26.4 mg/L). Furthermore, the rapid acidification combined with the production of nisin resulted in a strong anti-Listeria activity, reducing the pathogen loads below the detection limit, in carrot juice samples fermented by the strains LBG2 and FBG1P and in soymilk by the strain LBG2. The fermentation increased the presence of volatile molecules such as aldehydes and ketones with a positive impact on the organoleptic profile of both the fermented products. These results highlighted the interesting potential of three nisin producing L. lactis strains for the production of fermented carrot juice and soymilk. In fact, the fermentation by lactic acid bacteria, combined or not with other mild technologies, represents a good strategy for the microbiological stabilization of these products. Furthermore, the increase of molecules with a positive sensory impact, such as aldehydes and ketones, in the fermented products suggests a possible improvement of their organoleptic characteristics.

Role of soybean-derived bioactive compounds in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, inflammatory condition of the gastrointestinal tract. Patients with IBD present with debilitating symptoms that alter the quality of life and can develop into severe complications requiring surgery. Epidemiological evidence indicates Westernized societies have an elevated IBD burden when compared with Asian societies. Considering the stark contrast between the typical Western and Eastern dietary patterns, it is postulated that differences in food and lifestyle contribute to lower IBD incidence in Asian countries. Soybeans (Glycine max), which are consumed in high quantities and as various preparations in Eastern societies, contain a wealth of natural, biologically active compounds that include isoflavones, bioactive peptides, protease inhibitors, and phytosterols, among many others. These compounds have been shown to improve human health, and preclinical evidence suggests they have potential to improve the prognosis of IBD. This review summarizes the current state of evidence regarding the effects and the mechanisms of action of these soybean-derived bioactive compounds in experimental models of IBD.