Açaí Flan, A Functional Food with Lacticaseibacillus rhamnosus HN001 Probiotic: Physicochemical Characteristics, Probiotic Survival, Sensory Acceptance and Consumer Perception

Research background

Açaí berry is rich in antioxidant compounds and is therefore closely associated with beneficial health effects. In this study, we aim to investigate the potential of using Lacticaseibacillus rhamnosus HN001 as a probiotic culture on açaí flan.

Experimental approach

The chemical composition, physicochemical and microbiological characteristics, and sensory acceptance during refrigerated storage (5 °C for 42 days) of flan were investigated. In addition, the consumer perception of the product was evaluated using word association when consumers were shown a photo of the product with or without the added ingredients accompanied with a brief description of the product.

Results and conclusions

The flan had a suitable chemical composition, mainly carbohydrates and proteins, probiotic viability reached 8 log CFU/g in the product and 4 log CFU/g after gastrointestinal simulation, typical açaí coloration, significant antioxidant activity and high sensory acceptability. The information about the ingredients and properties of the products increased the health value and positive feelings of the consumers towards the product.

Novelty and scientific contribution

Açaí flan has proven to be a suitable carrier for L. rhamnosus HN001 as a probiotic culture, further enhancing the characteristic beneficial properties of the fruit. Therefore, combining this information with marketing strategies that inform consumers about the benefits of the product can further improve its acceptance. As far as we know, this is the first study on açaí flan with added probiotic culture.

Maturation of honey from Uruçú-Amarela (Melipona mondury): Metagenomics, metabolomics by NMR 1H, physicochemical and antioxidant properties

The objective of this study was to characterize the microbiota biodiversity of Uruçú-Amarela honey through metagenomics. Furthermore, the impact of maturation temperatures (20 and 30 °C) and time (0-180 days) on the physicochemical and antioxidant properties was investigated. ¹H NMR was performed to verify metabolites formed during maturation. Uruçú-Amarela honey was mainly composed by lactic acid bacteria and osmophilic yeasts of genus Zygosaccharomyces. Maturation at 30 °C led to a higher fermentation activity, resulting in greater carbohydrate consumption, ethanol formation (0.0-0.6 %) and increased acidity (34.78-45.74 meq/kg) over the 180 days. It also resulted in honey with higher brown color (a* 0.7 to 3.89, b* 17.50-25.29) and antioxidant capacity, corroborating that the maturation is a suitable preservation technique for stingless bee honey, because it does not cause negative changes as it extends the shelf life of the stingless bee honey.

Bacterial cellulose production by Komagataeibacter hansenii can be improved by successive batch culture

Bacterial cellulose (BC) is a biopolymer principally synthetized by strains of the genus Komagataeibacter. However, high costs and low production yield make large-scale application difficult. The aim of this work was to evaluate the effects of successive batch culture before fermentation on the ability to increase the capacity of bacterial cellulose biosynthesis by a low-producing strain. The Komagataeibacter hansenii strain ATCC 23,769 was initially cultivated in fermentation broth for two periods of 35 or 56 days under static conditions. At the end of each period of time, they were transferred to new broth to be cultivated again (new batch culture cycle) for 35 or 56 days and carried out in parallel with a 10-day fermentation to determine the quantity of BC produced. As a result, a greater increase was observed after the end of the second and third batch cultures of 56 days (increases of 137% and 187% in relation to the nonbatch cultured strain, respectively). The produced samples presented higher crystallinity and thermal properties but lower water holding capacity. Through this work, it was concluded that the longer the batch culture time was, the greater the increase in the capacity of cellulose biosynthesis, which also depended on the number of successive batch culture cycles carried out.

Spectralprint techniques coupled with chemometric tools for vinegar classifications

Vinegar is a versatile product used for food preservation, cooking, healthcare, and cleaning. In this study, 80 vinegar of different raw materials, aging time, and for the first time by the agronomic method of raw material cultivation were classified by spectralprint techniques with chemometrics. Datasets were obtained by proton nuclear magnetic resonance (¹H NMR), Fourier transforms mid-infrared (FT-IR), near-infrared (NIR), and ultraviolet-visible (UV-vis); then evaluated by common dimension (ComDim) and partial least squares-discriminant analysis (PLS-DA). NMR with PLS-DA had the best prediction performance compared to other techniques, with accuracy values between 92.3 and 100 %, followed by FT-IR and UV-vis of 80.8 and 96.0 % and NIR between 69.2 and 84.0 %. The results indicated that the classification of vinegar according to the agronomic cultivation method is more complex than aging time or raw material. However, any of these spectralprint techniques have demonstrated that they can be used in the classification of vinegar.

Role of Acetic Acid Bacteria in Food and Beverages

Acetic acid bacteria (AAB) are microorganisms widely distributed in nature. Although this group is involved in the spoilage of some foods, AAB are of great industrial interest, and their functionality is still poorly understood. AAB converts ethanol, sugars, and polyols into various organic acids, aldehydes, and ketones via oxidative fermentation. These metabolites are produced during a succession of biochemical reactions in various fermented foods and beverages, such as vinegar, kombucha, water kefir, lambic beer, and cocoa. Furthermore, important products such as gluconic acid and ascorbic acid precursors can be produced industrially from their metabolism. The development of new AAB-fermented fruit drinks with healthy and functional appeal is an interesting niche for research and the food industry to explore, as it can meet the needs of a wide range of consumers. Exopolysaccharides such as levan and bacterial cellulose (BC) have unique properties, but they need to be produced on a larger scale to expand their applications in this area. This work emphasizes the importance and applications of AAB during the fermentation process of various foods, as well as the role of AAB in the development of new beverages and the numerous applications of levan and BC.

Nutritional Supplementation with Amino Acids on Bacterial Cellulose Production by Komagataeibacter intermedius: Effect Analysis and Application of Response Surface Methodology

Bacterial cellulose (BC) is a biopolymer mainly produced by acetic acid bacteria (AAB) that has several applications in the medical, pharmaceutical, and food industries. As other living organisms, AAB require sources of chemical elements and nutrients, which are essential for their multiplication and metabolite production. So, the knowledge of the nutritional needs of microorganisms that have important industrial applications is necessary for the nutrients to be supplied in the appropriate form and amount. Considering that the choice of different nutrients as nitrogen source can result in different metabolic effects, this work aimed to verify the effects of amino acid supplementation in the culture media for BC production by an AAB strain (Komagataeibacter intermedius V-05). For this, nineteen amino acids were tested, selected, and optimized through a Plackett and Burman factorial design and central composite design to determine the optimal concentrations of each required amino acid. Membranes produced under optimal conditions were characterized in relation to chemical structure and properties by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), and hydrophilic properties. Three amino acids had a significant positive effect and were required: aspartic acid (1.5 g L^-1), phenylalanine (1.5 g L^-1), and serine (3.0 g L^-1). Conversely, all sulfur and positively charged amino acids had a negative effect and reduced the production yield. After optimization and validation steps, a production level of 3.02 g L^-1 was achieved. Membranes produced from optimized media by this strain presented lower crystallinity index but greater thermal and hydrophilic properties than those produced from standard HS medium.

Komagataeibacter intermedius V-05: An Acetic Acid Bacterium Isolated from Vinegar Industry, with High Capacity for Bacterial Cellulose Production in Soybean Molasses Medium

Research background

Despite the great properties of bacterial cellulose, its manufacture is still limited due to difficulties in large-scale production. These problems are mainly related to low production yields and high overall costs of the conventional culture media normally used. To surpass these problems, it is necessary to identify new cheap and sustainable carbon sources. Thus, this work aims to isolate and select a high cellulose-producing Komagataeibacter strain from vinegar industry, and study its potential for bacterial cellulose synthesis in an industrial soybean co-product, known as soybean molasses, used as fermentation medium.

Experimental approach

One isolated strain was able to produce high amount of cellulose in the standard Hestrin-Schramm medium, so we tested its ability to produce this biopolymer in a soybean molasses medium. The characteristics and properties of the produced bacterial cellulose membranes were analyzed by thermogravimetric analysis, X-ray diffraction, infrared spectroscopy, water-holding capacity and rehydration ratio. Genetic analysis of the selected strain served to determine its genus and species.

Results and conclusions

An isolated strain that produced the highest amount of cellulose in Hestrin-Schramm medium (3.7 g/L) was genetically identified as Komagataeibacter intermedius V-05. This strain produced 10.0 g/L of cellulose in soybean molasses medium. Membranes from both substrates had similar chemical structure, crystallinity and thermal degradation. Soybean molasses proved to be a suitable alternative medium for biosynthesis of cellulose in comparison with the standard medium. In addition to providing higher production yield, the membranes showed great structural characteristics, similar to those obtained from standard medium.

Novelty and scientific contribution

In this research, we have isolated and identified a Komagataeibacter strain which exhibits a high capacity for cellulose production in soybean molasses. The isolation and selection of strains with high capacity for microbial metabolite production is important for decreasing bioprocess costs. Furthermore, as there is a necessity today to find cheaper carbon sources to obtain microbial products at a lower cost, soybean molasses represents an interesting alternative medium to produce bacterial cellulose for its industrial application.

Effects of adding spices with antioxidants compounds in red ale style craft beer: A simplex-centroid mixture design approach

The growing demand for authentic products that provide sensory characteristics combined with health benefits has been the focus of current studies. This study developed a Red Ale style craft beer with spices such as turmeric (T), black pepper (P) and aroma hops (H), used isolated or in mixtures. A mixture design was employed to evaluate the total phenolic compounds and the antioxidant activity in the green and aged beers formulations. The spice extracts influenced the product's shelf-life. The addition of spices into the beers did not affect the physicochemical parameters that classify the Red Ale style, according to the hierarchical cluster analysis, except for aroma hops. A multiresponse optimization approach simultaneously maximized the antioxidant activity and the phenolic compounds in beers. The ideal formulation obtained for green beers was 25% T and 37.5% P and H; for aged beers, the formulation was 50% T, 20% P and 30% H.

Acetic Acid Fermentation of Soybean Molasses and Characterisation of the Produced Vinegar

Soybean molasses is a by-product from the production of protein concentrate from soybean meal that predominantly contains sugars, with sucrose as the major component. In Brazil, soybean molasses is used for animal feed or it is discarded, although some industries use it to produce ethanol. This study aims to evaluate the parameters required for the acetic acid fermentation of soybean molasses, and characterise the resultant vinegar. To study the most suitable parameters for the acetic acid fermentation, vinegar was produced from the alcohol fermentation of soybean molasses through eight fermentation cycles: five for adaptation and three for production. The average acidity of the acetic acid fermentation product was 50.60 g/L, with an acetic acid fermentation yield, total yield of acetic acid in broth and productivity 65.01%, 92.76% and 0.033 g/(L·h), respectively. The vinegar produced from soybean molasses has an acidity of 5.07% (m/V), residual ethanol content 0.17% (m/V), sugars 7.86% (m/V), dry extract 14.67% (m/V), ash 2.27% (m/V) and a density of 1.023 g/cm³. The contents of total phenolics and isoflavones decreased after the alcohol and acetic acid fermentations. Moreover, the isoflavones profile of the fermented product comprised only three forms: daidzein, glycitin and genistin. According to our results, 3460 L of vinegar can be produced for every tonne of soy molasses, with an acetic acid concentration of 40 g/L, the minimum required by the legislation on vinegar production. Thus, these findings demonstrate that soy molasses represents a useful raw material for the production of vinegar.

Acetic Acid Bacteria in the Food Industry: Systematics, Characteristics and Applications

The group of Gram-negative bacteria capable of oxidising ethanol to acetic acid is called acetic acid bacteria (AAB). They are widespread in nature and play an important role in the production of food and beverages, such as vinegar and kombucha. The ability to oxidise ethanol to acetic acid also allows the unwanted growth of AAB in other fermented beverages, such as wine, cider, beer and functional and soft beverages, causing an undesirable sour taste. These bacteria are also used in the production of other metabolic products, for example, gluconic acid, l-sorbose and bacterial cellulose, with potential applications in the food and biomedical industries. The classification of AAB into distinct genera has undergone several modifications over the last years, based on morphological, physiological and genetic characteristics. Therefore, this review focuses on the history of taxonomy, biochemical aspects and methods of isolation, identification and quantification of AAB, mainly related to those with important biotechnological applications.