Identification of Putative β-Galactosidase Genes in the Genome of Lactobacillus helveticus OSU-PECh-4A

The Lactobacillus helveticus OSU-PECh-4A strain, from the Ohio State University Parker Chair collection, produces exceptional β-galactosidase activity using acid whey as a culture medium, compared with a commercial broth. The strain has a genome sequence of 1,834,843 bp, and its GC content is 36.69%. Using InterProScan v5.50-84.0 software, four genes with putative β-galactosidase function were found.

Fermentation of Dairy-Relevant Sugars by Saccharomyces, Kluyveromyces, and Brettanomyces: An Exploratory Study with Implications for the Utilization of Acid Whey, Part I

Acid whey from Greek-style yogurt (YAW) is an underutilized byproduct and a challenge for the dairy industry. One alternative is the fermentation of YAW by yeasts such as Saccharomyces, Brettanomyces, and Kluyveromyces spp., to produce new styles of fermented beverages. Previous research in our group suggested that the sugar profiles of the dairy coproducts impacted the fermentation profiles produced by B. claussenii. The present work aims to describe the fermentation of dairy sugars by S. cerevisiae, K. marxianus, and B. claussenii, under conditions comparable to those of YAW. For this purpose, four preparations of yeast nitrogen base, each containing 40 g/L of either lactose (LAC), glucose (GLU), galactose (GAL), or a 1:1 mixture of glucose and galactose (GLU:GAL), all at pH 4.20, were used as fermentation media. The fermentation was performed independently by each organism at 25 °C under anoxic conditions, while density, pH, cell count, ethanol, and organic acids were monitored. Non-linear modeling was used to characterize density curves, and Analysis of Variance and Tukey’s Honest Significant Difference tests were used to compare fermentation products. K. marxianus and S. cerevisiae displayed rapid sugar consumption with consistent ethanol yields in all media, as opposed to B. claussenii, which showed more variable results. The latter organism exhibited what appears to be a selective glucose fermentation in GLU:GAL, which will be explored in the future. These results provide a deeper understanding of dairy sugar utilization by relevant yeasts, allowing for future work to optimize fermentations to improve value-added beverage and ingredient production from YAW.

Effect of Acid Whey, Enzymatic Whey, Magnetized and Unmagnetized Whey on the Qualitative and Productive Traits of Date Palm

This study was conducted in one of the private orchards in the district of Abu Al-Khaseeb, Basrah province during the growing seasons 2017 - 2018 in order to examine the effect of spraying acidic whey, enzymatic whey and magnetized and non-magnetized whey on date palm cultivars Phoenix dactylifera L. agricultural (yellow Shwithi and Al-Khdrawi). A Concentration of 100% of the whey was applied to the fruits. The results of the study showed the superiority of the yellow Shwithi and Al-Khdrawi regarding the Qualitative and Productive characteristics. There was a significant difference between the date palm cultivars regarding the length, diameter, the weight of fruit, dry matter, total and reduced sugars and fruit content of invertase enzyme were recorded 33.45 mm, 20.89 mm, 9.302 g, 37.685%, 50.28%, 36.09% and 2347 units/kg/ CO2. The spray treatment was characterized by enzymatic whey in most of the study treatments of fruit length, fruit weight, total sugars and invertase enzyme. It reached 34.55 mm, 9.883 g, 56.15% and 2005.3 units/kg/CO2. The results also showed the importance of bilateral interaction between the variety and spray treatment.

The Influence of Acid Whey on the Lipid Composition and Oxidative Stability of Organic Uncured Fermented Bacon after Production and During Chilling Storage

The aim of this research was to evaluate the effect of acid whey on changes in the fatty acid profile, oxidative stability, physico-chemical parameters, and microbiological and sensory quality of traditional organic uncured fermented Polish bacon after production and during chilling storage. Three different treatments of fermented bacon were produced: C—control bacon with a nitrite curing mixture; T—bacon with a nitrate curing mixture; and AW—bacon with acid whey and NaCl. The acid whey used in the production of uncured fermented pork bacon positively changed the sensorial characteristics, directly after the ripening process, and had a positive effect in terms of a decrease in the pH of the product. All of the fermented bacon treatments in general were of good microbiological quality. A higher lactic acid bacteria (LAB) level was observed in the AW treatment after the fermentation process, and the bacteria number did not change during storage, whereas in the C and T treatments, the LAB level increased during storage (p < 0.05). The application of acid whey did not limit the formation of secondary oxidation products (TBARS) during bacon ripening (1.68 mg MDA kg−1), but had a reduced value during storage time (0.73 mg MDA kg−1). The highest polyunsaturated fatty acid (PUFA) levels, after ripening and after four weeks of refrigerated storage, were found in the C treatment. In the AW treatment, it was found that the PUFA level increased; likewise, the content of n-3 and n-6 fatty acids increased, while saturated fatty acids (SFAs) decreased during storage (p < 0.05). The opposite tendency was observed in the C treatment. After four weeks of storage, the PUFA/SFA ratio was the lowest in the nitrate treatment, and higher values of the PUFA/SFA ratio were obtained in the acid whey and nitrite treatment (p < 0.05).

A Note on the Effects of Yoghurt Acid Whey Marination on the Tenderness and Oxidative Stability of Different Meat Types

The aim of this preliminary study was to examine the effects of yoghurt acid whey (YAW) marination on quality parameters and the oxidative stability of pork, lamb, rabbit and chicken meat. Twenty-four samples per meat type were randomly allocated to one of four groups: CON, without any treatment; YAW1 and YAW2, where samples were marinated for 20 h at 4 °C at a pH of 5 or 4.5, respectively; and YAW3, where samples were treated as in the YAW2 group except hesperidin was also added at the level of 2 g/L. As indicated, meat tenderness was improved as a result of YAW marination, apart from the chicken samples. In general, values of pH, redness and yellowness were decreased after immersion in YAW both in raw and cooked samples. However, lightness was increased in the raw meat samples as a result of YAW marination, though this effect was not observed in the cooked meat samples with the exception of chicken meat. Chroma values were higher in controls compared to YAW-treated groups in raw pork and lamb meat, while no significant differences regarding chroma were found among groups in cooked lamb and rabbit meat. Hue angle values were greater in YAW-treated groups compared to controls in raw samples, whereas no significant differences among groups were indicated in cooked meat. Meat oxidation rates were not affected by treatment with YAW and the hesperidin addition, which improved the oxidative stability of lamb and chicken meat. Thus, YAW marination could be recommended as a novel strategy that improves meat tenderness without negative effects on the other quality characteristics.

Valorisation of whey for lactose recycling products production = Sūkalu valorizācija laktozes pārstrādes produktu ieguvei

The doctoral thesis “Valorisation of whey for lactose recycling products production” was developed from 2016 to 2021. Experiments were carried out in the research laboratories of the Faculty of Food Technology, Latvia University of Life Sciences and Technologies; Dairy Innovation Institute, California Polytechnic State University (USA); Institute of Microbiology and Biotechnology, Latvia University; Faculty of Chemistry, Latvia University; Institute of Solid State Physics, Latvia University and J.S. Hamilton Baltic Ltd. The aim of the doctoral thesis was to improve the lactose hydrolysis process for obtaining glucose-galactose and oligosaccharide syrups. The hypothesis of the doctoral thesis – the two-stage fermentation increases the sweetness of glucose-galactose syrup. The hypothesis of the doctoral thesis has been confirmed by the defended thesis: 1. The presence of cations affects the β-galactosidase activity in the sweet and acid whey permeate. 2. The chemical composition and quality of whey affect the physical properties of lactose. 3. Enzymatic reactions affect the functional and sensory properties of syrups. The research objects – sweet and acid whey permeates, glucose isomerase, commercial β-galactosidases and glucose-galactose syrup. The following tasks were set to achieve the aim of the doctoral thesis: 1. To evaluate the effect of cation concentration to ensure the β-galactosidase activity in substrate. 2. To investigate the physical properties of whey lactose in order to better understand its behaviour. 3. To study the changes of monosaccharide concentration in the lactose hydrolysis, varying with the solids concentration of the substrates and enzyme units. 4. To assess the possibilities of glucose isomerase to increase the sweetness of glucose-galactose syrup. 5. To evaluate the sensory properties of the developed syrups. The novelty of the doctoral thesis: 1. The study of the relationship of lactose hydrolysis process in the formation of galacto-oligosaccharides and lactulose. 2. The combination of β-galactosidase and glucose isomerase increases the sweetness of glucose-galactose syrup. The economic significance of the doctoral thesis: 1. The studies have shown the possibility to obtain syrup that can be used as sugar and sweeteners replacer in the food industry and to produce functional products. 2. A technological solution for hydrolysis of lactose is proposed, comprehensively evaluating the physical properties of lactose, fermentation parameters and whey composition. The doctoral thesis consists of three chapters: Chapter 1 describes the composition of whey and the possibilities of using it. An overview of the chemical and physical properties of lactose, lactose hydrolysis methods, the application of β-galactosidases and the properties of glucose-galactose syrup are provided. Chapter 2 summarises the materials and methods used in the thesis. Chapter 3 provides a summary of the results obtained in the study, the properties of commercial enzymes in different cation concentrations, the stability of enzymes in the gastrointestinal tract model, methods for the determination of lactose, the properties of dehydrated permeates are evaluated. The influence of factors on the hydrolysis of permeates and the profile of the obtained sugars was analysed. Possibilities for lactulose synthesis are considered. Sensory analysis of glucose-galactose syrups and syrups obtained in the two-stage fermentation are given. During the PhD studies the author had an internship at the Dairy Innovation Institute California Polytechnic State University (USA), where the experimental work was done. Internship was provided by the Baltic – American Freedom Foundation (BAFF) and the Council on International Education Exchange (CIEE). The study was partly financed by the LLU programme “Strengthening Research Capacity at the Latvia University of Agriculture” grant (Contract No. 3.2.-10/2017/LLU/27) “The optimization of bioprocesses for lactose recycling products”. The study was partly financed by the doctoral studies grant “Transition to the new doctoral funding model at the Latvia University of Life Sciences and Technologies” (Contract No. 3.2.-10/90). The thesis is written in English, it consists of 111 pages, 32 tables, 41 figures, 3 appendixes, and 233 bibliographic sources.