Starter Lactic Acid Bacteria Research Articles

Screening appropriate lactic acid bacteria as adjunct starter to enhance characteristic flavor and sensory profiles of Huangjiu (Chinese rice wine)

Lactic acid bacteria (LAB) are crucial for enhancing Huangjiu flavor, yet no standardized criteria exist for selecting LAB strains for this purpose. This study aimed to investigate the suitability of screening appropriate LAB strains as adjunct starters for Huangjiu fermentation. Twenty-five LAB strains were assessed for their stress resistance and fermentation characteristics. Co-fermentation with Saccharomyces cerevisiae was conducted to explore its role in flavor development, as this yeast greatly contribute to desirable flavor profiles. Notably, Lactiplantibacillus plantarum AR1018, AR1026 and Weissella confusa AR1038 significantly reduced 3-methyl-1-butanol production while increasing levels of ethyl hexanoate and ethyl octanoate. These strains were selected for further analysis of their impact on the physicochemical properties, volatile organic compounds, and sensory attributes of Huangjiu. The LAB starters enhanced total acidity, sugar and protein utilization and ester synthesis, while reducing ethanol and alcohol levels. AR1018 achieved a 16.51% reduction in 3-methyl-1-butanol, whereas AR1038 exhibited a 27.32% increase in ester content compared to the control. Principal component analysis revealed distinct flavor characteristic between Huangjiu produced with AR1018 and AR1038, and sensory evaluation confirmed enhanced desirable attributes, especially for AR1038. This study highlights the potential of LAB starters in improving the flavor quality of rice wine and similar fermented beverages.

Chemical, Textural and Antioxidant Properties of Oat-Fermented Beverages with Different Starter Lactic Acid Bacteria and Pectin.

Currently, starter cultures for fermenting plant-based beverages are not widely available commercially, but producers can use starter cultures for dairy products. Therefore, the aim of this study was to determine the physicochemical, rheological, antioxidant and sensory properties of oat beverages with/without pectin fermented by four different dairy starter cultures. The use of a mono-starter with Lactobacillus bulgaricus or Sreptococcus thermophilus allows for the efficient use of glucose, and more lactic acid is accumulated. The beverage with L. bulgaricus is characterised by high adhesion, syneresis and low cohesiveness, and it has high antioxidant activity and a low sensory profile. Using starter with L. bulgaricus, S. thermophilus and some Lactococcus for fermentation yields a product with high sensory capacity, forming a high-viscosity beverage matrix with low syneresis, high water retention, chewy texture and stickiness. It has been observed that the absence of lactococci and the presence of Lactobacillus casei, L. Rhamnosus and L. paracasei in the starter yields a product with high antioxidant activity, especially in the presence of pectin. The use of pectin significantly improves the viscosity and textural properties of oat yoghurt, enhancing the drink's flavour and giving it body. For many reasons, the use of different commercial starters in the dairy industry results in different viscosities of oat fermented beverages, forming a matrix with different textural, sensory and antioxidant properties.

CHARACTERISTICS OF JUWET FRUIT YOGHURT WITH THE ADDITION OF SKIM MILK AND LACTIC ACID BACTERIA STARTER

In this study, the manufacture of juwet fruit yoghurt was studied with different treatments of adding skim milk and lactic acid bacteria starter. Yogurt is a processed milk product made through bacterial fermentation. Yogurt is known as a good source of protein, calcium, and probiotics, which can support digestive health and the immune system. Juwet fruit has a high antioxidant and vitamin C content so that juwet fruit has interesting potential to be made into yoghurt. Skim milk is used to utilize high lactose and protein so that the growth of lactic acid bacteria can grow optimally. Lactic acid bacteria are used for preservation, providing texture, and adding flavor to yoghurt drinks. The purpose of this study was to determine the addition of skim milk and lactic acid bacteria starter on the physicochemical, microbiological, and organoleptic characteristics of juwet yoghurt. This study used a Completely Randomized Design (CRD) factorial pattern consisting of two factors. Factor 1 addition of skim milk (5%, 7%, 9%). Factor 2 addition of starter (5%, 7%, 9%). Each treatment was repeated three times. The data obtained were analyzed using analysis of variance (ANOVA). If there is a significant difference between treatments, it is continued with the Duncan test (DMRT) and organoleptic test using the Scoring test with 25 trained panelists. The treatment of adding 9% skim milk and 9% starter was the best treatment that produced juwet yoghurt with a protein content of 2.1% ± 0.036, total titratable acid 2.1% ± 0.1, total soluble solids 22.7ºBrix ± 1.53, total lactic acid bacteria 10.5 log CFU/ml ± 0.023, pH 3.7 ± 0.058, antioxidants 34.0% ± 0.117, viscosity 6.8% ± 0.058, Vitamin C 5.8 ± 0.3, and organoleptic tests of color 2.88 (rather like), taste 3.24 (rather like), aroma 2.68 (rather like), texture 3.76 (like).

Lactic and propionic acid bacteria starter cultures for improved nutritional properties of pea, faba bean and lentil

Increasing plant-based food consumption as a sustainable and health-oriented alternative to meat is pivotal. Pulses are rich in proteins, minerals, and vitamins; however, they also contain antinutritional compounds, impairing their nutritional value. This study addresses this challenge through the development and application of four distinct microbial consortia in pulse-based fermentations, featuring lactic acid bacteria or a combination of lactic and propionic acid bacteria. Microbial starters significantly reduced galacto-oligosaccharides in all pulse materials, concurrently degrading vicine and convicine in faba beans, while the impact on tannins in faba beans and lentil was moderate. Fermentation with lactic acid and propionic acid bacteria consortia exhibited notable vitamin B12 production, and the effect on the content of phenolic compounds of the studied pulses was also evidenced. Additionally, genomic analyses discerned distinctive profiles among the samples, elucidating the microbial community dynamics shaping fermentation outcomes. The results of this study proved how fermentation can advance the development of pulse-based products with improved nutritional and sustainability attributes.

Fermentation of Rice, Oat, and Wheat Flour by Pure Cultures of Common Starter Lactic Acid Bacteria: Growth Dynamics, Sensory Evaluation, and Functional Properties.

Recent consumer demand for non-dairy alternatives has forced many manufacturers to turn their attention to cereal-based non-alcoholic fermented products. In contrast to fermented dairy products, there is no defined and standardized starter culture for manufacturing cereal-based products. Since spontaneous fermentation is rarely suitable for large-scale commercial production, it is not surprising that manufacturers have started to adopt centuries-known dairy starters based on lactic acid bacteria (LABs) for the fermentation of cereals. However, little is known about the fermentation processes of cereals with these starters. In this study, we combined various analytical tools in order to understand how the most common starter cultures of LABs affect the most common types of cereals during fermentation. Specifically, 3% suspensions of rice, oat, and wheat flour were fermented by the pure cultures of 16 LAB strains belonging to five LAB species-Lacticaseibacillus paracasei, Lactobacillus delbrueckii, Lactobacillus helveticus, Streptococcus thermophilus, and Lactococcus lactis. The fermentation process was described in terms of culture growth and changes in the pH, reducing sugars, starch, free proteins, and free phenolic compounds. The organoleptic and rheological features of the obtained fermented products were characterized, and their functional properties, such as their antioxidant capacity and angiotensin-converting enzyme inhibitory activity, were determined.

Plant-Based Alternatives to Mold-Ripened Cheeses as an Innovation among Dairy Analogues.

There is a growing demand for vegan products and plant-based food when dealing with the impact of livestock on the climate crisis. The aim of this study was to develop a formulation for a plant-based analogue of mold-ripened cheese. Were investigated the following plant materials: cashews, pistachios, soy flour, chickpea flour, pea protein, pumpkin protein, hemp protein, and spirulina powder. Plant matrices were fermented with lactic acid bacteria (LAB) starter cultures and cheese starter cultures of mold species Geotrichum candidum and Penicillium camemberti. All microorganisms' growth were tested in a vegan-type culture medium. Calcium supplementation was applied and followed by an in-depth analysis of the elemental composition of selected analogues with inductively coupled plasma optical emission spectroscopy. The physicochemical and organoleptic analyses of plant-based alternatives of Camembert were conducted. This is the first paper describing novel formulations for plant-based alternatives for Camembert cheese prepared with techniques mimicking the original milk product.

Refermentation with yeast and lactic acid bacteria isolates: a strategy to improve the flavor of green coffee beans.

Yeast and lactic acid bacteria (LAB) play an important part in the post-harvest fermentation of coffee. This study applied lab-scale fermentation to commercial green coffee beans using dry coffee pulp as the substrate, with the aim of modifying coffee-bean flavor. In addition to spontaneous fermentation, yeast and LAB isolated from coffee beans and dried coffee pulp were added during fermentation. Co-inoculation of yeast and LAB showed a significant effect on the chlorogenic acid content after between 24 and 72 h of fermentation. Acetic, citric, malic, lactic, and quinic acids were shown to be affected significantly (P < 0.05) by fermentation and inoculation. Gas chromatography detected that esters, alcohols, aldehydes, furans, and pyrazines were the primary compounds in the coffee beans. Certain volatile groups were present in greater concentrations and broader varieties within the inoculated beans. The highest cupping scores were given to beans that had been co-inoculated with yeast and LAB. Overall, the use of yeasts and LAB starters showed potential to create coffee beverages with desirable characteristics by standardized fermentation. © 2024 Society of Chemical Industry.

Effects of Lactic Acid Bacteria on Reducing the Formation of Biogenic Amines and Improving the Formation of Antioxidant Compounds in Traditional African Sourdough Flatbread Fermentation.

This study investigated the safety and functionality of traditional African sourdough flatbread (kisra), based on the content of biogenic amines (BAs) and antioxidant compounds and their improvement using lactic acid bacteria (LAB) species. The primary BAs detected in naturally fermented kisra were tyramine, histamine, putrescine, and cadaverine, with putrescine being the most abundant after baking. In vitro BA production of microorganisms isolated from kisra sourdough revealed that the Enterococcus genus contributed to tyramine accumulation, whereas presumptive yeasts may contribute to putrescine and cadaverine accumulation. The use of LAB species, including Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Levilactobacillus brevis, and Weissella cibaria, significantly reduced putrescine content to less than about 23% of that of naturally fermented kisra, and eliminated tyramine, histamine, and cadaverine formation. Meanwhile, DPPH scavenging activity, total polyphenolic content, and tannin content in naturally fermented kisra were 85.16%, 1386.50 µg/g, and 33.16 µg/g, respectively. The use of LAB species did not affect the DPPH scavenging activity or tannin content but significantly increased the total phenolic content by up to 20% compared to naturally fermented kisra. Therefore, fermentation with LAB starter cultures might be a promising approach to improve the safety related to BAs as well as the functionality of kisra bread.

Unraveling the Metabolic Behavior and Interspecific Interaction Pattern of Lactic Acid Bacteria within Chinese Rice Wine.

The synthetic community of lactic acid bacteria (LAB) is commonly utilized in the food industry for manipulating product properties. However, the intermediate interactions and ecological stability resulting from metabolic differences among various LAB types remain poorly understood. We aimed to analyze the metabolic behavior of single and combined lactic acid bacteria in China rice wine based on microbial succession. Three-stage succession patterns with obligate heterofermentative LAB dominating prefermentation and homofermentative LAB prevailing in main fermentation were observed. Facultative heterofermentative LAB exhibited significant growth. Pairwise coculture interactions revealed 63.5% positive, 34.4% negative, and 2.1% neutral interactions, forming nontransitive and transitive competition modes. Nontransitive competitive combinations demonstrated stability over ∼200 generations through amino acid (mainly aspartic acid, glutamine, and serine) cross-feeding and lactic acid detoxification, which also showed potential for controlling biogenic amines and developing LAB starter cultures. Our findings offer insights into the mechanistic underpinnings of LAB interaction networks.

Selection of starter lactic acid bacteria capable of forming biofilms on wooden vat prototypes for their future application in traditional Sicilian goat's milk cheese making

In this study, 327 presumptive lactic acid bacteria (LAB) were isolated from goats' milk acid curds produced at a Sicilian dairy farm with the aim to identify potential starter cultures for traditional cheeses. All isolates were first processed by randomly amplified polymorphic DNA (RAPD)-PCR analysis. This approach identified 63 distinct strains which were evaluated for their acidifying capacity. Only 15 strains specifically stood out for their acidification capacity and were identified through 16S rRNA gene sequencing as Lactococcus lactis (11 strains) Enterococcus faecalis (three strains), and Ligilactobacillus animalis (one strain). Notably, all 15 LAB isolates produced bacteriocin-like inhibitory substances and anti-biofilm compounds, against both planktonic and biofilm forms of Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli, and Staphylococcus aureus, albeit at varying levels. Among these 15 LAB, En. faecalis RGM25 and Lc. lactis RGM55, susceptible to five antibiotics tested, were put in contact with wooden vat prototypes, because all equipment used in traditional cheese production in Sicily are made of wood. Scanning electron microscopy and bacterial plate counts of the wooden vat prototypes showed the development of biofilms at levels of approximately 6.0 log CFU/cm2. Overall, this study contributes to establishing a custom-made LAB starter cultures with bio-preservatives properties for Sicilian cheese productions.

Development of a defined mixed starter culture for the improvement of Tej, Ethiopian honey wine.

Ethiopian honey wine, Tej, is the most popular traditionally fermented alcoholic beverage in Ethiopia. Owing to the spontaneous fermentation process, the final product is neither predictable nor consistent in quality. Attempts have not been made before to solve this problem. Thus, the aim of this study was to develop a potential mixed starter culture of yeast and lactic acid bacteria isolated from Tej samples for the production of Tej with consistent quality. One hundred seventy-seven lactic acid bacteria and 194 yeasts were isolated from 30 Tej samples collected from southwest Ethiopia. After sequentially testing the isolates towards physiological stress tolerance and desired metabolic products, 10 lactic acid bacteria and 10 yeast isolates were screened. Later, four lactic acid bacteria and four yeast isolates were found to be compatible in co-culture tests. Finally, the combination of lactic acid bacteria and yeast isolates was formulated using the design of expert version 7.0.0 software, and six formulates (F #1-6) were designed. Controlled Tej fermentation was performed under laboratory conditions using six lactic acid bacteria-yeast starter culture formulations. The sensory attributes, in terms of color, flavor, odor, turbidity, and overall acceptance analysis scored 4.8/5.0 (F #2) and 4.7/5.0 (F #6), with mean significant variations (p < 0.05) among the other formulates. These two formulates were considered the best-mixed starter cultures compared to the control and other formulates. Matrix-assisted laser desorption ionization-time of flight analysis revealed that the lactic acid bacteria starters (AAUL7 and AAUL10) belonged to Lactobacillus paracasei. While the yeast starters (AAUY2 and AAUY8) belonged to Saccharomyces cerevisiae. These mixed lactic acid bacteria-yeast starter cultures could be used as the best starter culture for the fermentation of Ethiopian honey wine, Tej, with consistent quality.

Effect of lactic acid bacterial starter KUB-G2 on grass silage quality and its microbial community performed using 140-ton plastic bag silos: a large-scale study

This study investigated the effectiveness of lactic acid bacteria (LAB) starters in 140 tons of signal grass silage. We compared a locally developed starter, a combination of Lactiplantibacillus plantarum KUB-SP1-3 and Pediococcus acidilactici KUB-M6 (KUB-G2) with a commercial starter. We monitored the chemical and microbiological properties of silage at ensiling (day 0) and after 21 days. The results indicated that KUB-G2 produced high-quality silage. There were no significant differences in total viable microbes, lactic acid, or propionic acid contents between the starters. However, the silage produced with KUB-G2 had a lower acetic acid content than that produced with the commercial starter. KUB-G2 also resulted in a narrower microbiome profile dominated by Pediococci whereas the control group displayed a broader range of bacterial taxa with colonization by Lactiplantibacillus and Lentilactobacillus. These findings suggested that KUB-G2, with its distinct microbial profile, is a suitable replacement for imported commercial starters in large-scale signal grass silage production.

Effect of black bean supplemented with wheat bran sourdough fermentation by Pediococcus acidilactici or Pediococcus pentosaceus on baking quality and staling characteristics of wheat composite bread

The effects of black bean supplemented with wheat bran sourdough fermented by phytase and β-glucosidase producing Pediococcus acidilactici (L19) and Pediococcus pentosaceus (J28), respectively, on baking quality and staling characteristics of wheat composite bread were investigated. Compared to controls (12.21-15.33 mg/g), phytate content decreased (p < 0.05) in sourdoughs (higher decline in L19 than J28 sourdoughs). Also, relative to controls, the lactic acid (26.87-48.82 mg/g) and acetic acid (2.62-12.33 mg/g) increased (p < 0.05), while the total dietary fiber (TDF) decreased by 22.73 to 38.83 % and soluble dietary fiber (SDF) increased by 22.29 to 78.02 % in sourdoughs. In bread, phytate content decreased (p < 0.05) from 8.68-11.15 mg/g in controls to 0.95-3.21 mg/g in bread prepared with sourdoughs: greater decline in L19 than J28 sourdoughs with wheat bran and black bean. Compared to controls, SDF increased from 0.78-1.63 to 1.17-2.82 mg/g in breads prepared with sourdoughs: higher increase in J28 than L19 sourdoughs with wheat bran in black bean. Subsequently, specific volume increased, crumb firmness and chewiness reduced, staling rate during storage declined and overall sensory acceptance increased in breads prepared with sourdoughs than controls. Particularly, use of J28 than L19 starters and supplementation of wheat bran in black bean sourdough led to better outcomes. Therefore, sourdough acidification, the additive effect of wheat bran in black bean enhanced TDF in sourdough: this increased enzyme activity and synthesis of metabolites which were responsible for the improved baking quality, sensory acceptance and staling properties of breads prepared with sourdough. In conclusion, the use of carefully selected lactic acid bacteria starters, wheat bran supplementation in black bean flour sourdough improved the baking quality, shelf-life and staling properties of bread.

New generation of functional yogurts fermented with probiotic lactic acid bacteria isolated from human milk

Background: The cultures used in the production of "bio-yoghurts" typically consist of a blend of traditional yogurt starters, such as S. thermophilus and L. delbrueckii subsp. bulgaricus, along with probiotics like L. acidophilus, L. casei, L. reuteri, and Bifidobacterium spp. These probiotics, although beneficial, face challenges thriving in milk due to its short fermentation time (4–5 hours). The rapid acidification caused by the starter’s results in probiotic levels dropping below the "therapeutic minimum" during the intended refrigerated shelf life of the product. A potential solution to this issue lies in leveraging lactic acid bacteria isolated from the human milk which possess both robust probiotic characteristics and starter properties. Incorporating such strains in yogurt starter could address the acidity imbalance and contribute to maintaining optimal probiotic levels throughout the refrigerated shelf life of the product. Objective: This research aims to develop a new generation of sustainable functional yoghurts suitable for consumers of all ages using as starters predominant probiotic lactic acid bacteria isolated from the breast milk of healthy women. Results: This study marks the first implementation of the critical dilution culture method in sterile cow milk for the selection of predominant lactic acid bacteria (LABs) from women's breast milk. Remarkably, all samples yielded LAB capable of independently fermenting milk. Although breast milk is a good medium for the growth of residential lactic acid bacteria, it never coagulates due to low concentration of caseins. The isolated strains, identified as belonging to the species L. delbrueckii subsp. lactis, L. fermentum, L. casei subsp. sakei, Streptococcus thermophiles and Lactococcus lactis, exhibited probiotic and adaptive properties essential for gut colonization in humans. Utilizing symbiotic LAB starters were created functional yogurts with heightened technological, physicochemical, and sensory characteristics. Conclusions: Yogurts fermented using human milk LABs are safe and can be recommended as a functional dairy food, for pregnant women as well as for pre-term and full-term infants as a substitute/supplement for mother's milk. Moreover, these LABs can be included in infant formulas or used in pre-treatment of infant formula milk to improve its nutritional value and safety. Keywords: Breast milk, lactic acid bacteria, probiotic, milk fermentation, functional yogurt

Assessment of Microbial Interactions between Potential Lactic Acid Bacteria Starters and Major Microorganisms During in vitro Fermentation in a Medium Similar to Cocoa Pulp in Côte d'Ivoire

However, uncontrolled or random fermentations carried out in the country by farmers producing marketable cocoa beans of variable quality. The problem of variability in the quality of beans has led to significant economic losses in the country estimated at several billion CFA Francs. The objective of this work was to analyze the interactions between potential starter lactic acid bacteria and the major microorganisms selected during cocoa fermentations in Côte d’Ivoire. The work methodology began with the cultivation of yeast, lactic acid bacteria, acetic acid bacteria and Bacillus strains in their respective YPG, MRS, YEPG and BN media for 48 hours at 30°C. Then, the microbial load of each culture was determined and set at 105 cells/mL. The strains were subsequently placed in the similar interaction medium of cocoa pulp (PSM) alone (monoculture) or together (coculture) for the study of microbial interactions. This study took place over 5 days and samples were taken for analyzes after 0, 48 and 120 hours of incubation at 30°C. The interaction was monitored by assessing microbial growth using optical density and Thoma cell counts for monocultures and agar media for cocultures. Additionally, acid production and reduction in sugar intake were also measured over the 5 days. All crops showed good growth. Growth was greater in cocultures with values ​​ranging from 4.12 log (CFU/mL) to 9.21 log (CFU/mL). In addition, the cocktails acidified the environment much more than the monocultures with values ​​oscillating between 0.10 ± 0.00 and 0.21 ± 0.00. Also, the quantity of sugars in the different broths decreased significantly in the cocktails during the first 48 hours, going from 1.08 ± 0.08 to 0.20 ± 0.01. Microbial starters in monocultures and cocultures have shown their ability to adapt to the environment like cocoa pulp. The high microbial growth, sugar consumption, and acidification of the medium in the cocktails reflected a synergistic interaction between the strains during fermentation when they were together. In short, these strains could be used for a starter composition to control fermentation and obtain good quality beans.

Characterization and technological functions of different lactic acid bacteria from traditionally produced Kırklareli white brined cheese during the ripening period

In the present study, the evolution of the physicochemical and microbiological characteristics of lactic acid bacteria (LAB) in traditional Kırklareli white brined cheese collected from 14 different cheese manufacturing facilities were investigated on different days of the 90-day ripening period. The obtained LAB within the species Lactococcus (Lc.) lactis, Latilactobacillus (Lt.) curvatus, Lactobacillus (Lb.) casei and Lb. plantarum, Enterococcus (E.) durans, E. faecium, E. faecalis, Streptococcus macedonicus, and Weissella paramesenteroides were characterized in terms of their influence on technological properties and their potential as starter cultures for traditional white brined cheese production. The results of the microbiological and physicochemical investigations showed that a few selected isolates of Lc. lactis, Lb. casei, and Lb. plantarum had certain functions as starter germs. Moderate acidification capacity, antibacterial activity and proteolytic activity, which are characteristic of their use as starter lactic acid bacteria, were found. Importantly, antibiotic resistance among selected Lc. lactis, Lb. casei, and Lb. plantarum isolates was extremely low, whereas some of these isolates demonstrated antibacterial activity against major foodborne pathogenic bacteria. Based on the results obtained in this study, selected Lc. and Lb. isolates can also be considered as starter culture in traditional cheese production.

Indigenous lactic acid bacteria as a biological control agent to prevent fungi contamination in the fermentation of cocoa beans

The contamination of mycotoxin-producing fungi during cocoa fermentation is a major concern of cocoa bean quality. This research aimed to investigate the effect of indigenous lactic acid bacteria starter culture, Lactiplantibacillus plantarum subsp. plantarum HL-15, on the fungi population and the quality of cocoa beans. Fermentation of cocoa beans was carried out by four treatments, namely, fermentation without starter culture in the used box, fermentation with starter culture in the used box, fermentation without starter culture in the new box, and fermentation with starter culture in the new box. The population dynamics of yeast, lactic acid bacteria, acetic acid bacteria, and fungi during fermentation were evaluated. The addition of L. plantarum subsp. plantarum HL-15 ensured the rise of temperature in the fermentation. There were changes in the growth pattern of these microorganisms during fermentation as the effect of starter culture addition. The addition of L. plantarum subsp. plantarum HL-15 effectively inhibited fungi growth. Fermentation using starter culture in newly made boxes was the most effective method to inhibit fungi growth and improve cocoa bean quality. Fermented cocoa beans produced by this method can adhere to the requirements of first-grade quality cocoa beans based on the Indonesian National Standard.

The Effect of Sucrose and Yeast Extract on Total Phenolic, Flavonoid, and Anthocyanin of Lactic-Acid-Fermented Mangosteen Fruit Peel (Garcinia mangostana L.).

This study aimed to determine the most suitable concentration of sucrose and yeast extract (SYE) and its impact on the levels of total phenol, flavonoid, and anthocyanin (TPFA) for lactic acid fermentation in mangosteen fruit peel. In this study, the primary components were mangosteen fruit peel, SYE, and lactic acid bacteria starter. The experimental design was conducted using the Factorial Design method. The colorimetric method was used to determine the total phenol (Folin-Ciocalteu reagent) and total flavonoid (AlCl3 reagent). In addition, the differential pH method was used to determine the total anthocyanins using KCl and the CH3COONa reagent. The addition of SYE during the fermentation of mangosteen fruit peel significantly increased the concentrations of TPFA compared with the control (p value of 0.0001). The high sucrose concentration and low yeast extract produced the highest TPFA levels in mangosteen rind fermentation. The use of SYE affects the levels of TPFA in lactic acid-fermented mangosteen fruit peel, with the most suitable concentrations obtained using sucrose (45 g/L) and yeast extract (2.5 g/L).

Lacticaseibacillus Strains Isolated from Raw Milk: Screening Strategy for Their Qualification as Adjunct Culture in Cheesemaking.

The microbial ecology fundamentals of raw milk and long-ripened cheeses consist of a complex interaction between starter lactic acid bacteria (SLAB) and non-starter LAB (NSLAB). Although NSLAB aromatic properties are paramount, other phenotypic traits need to be considered for their use as adjunct cultures, such as the capability to endure technological parameters encountered during cheesemaking. The present study focused on the isolation and characterization of NSLAB from spontaneously fermented raw cow's milk coming from 20 dairies that produce Grana Padano PDO cheese. From 122 isolates, the screening process selected the 10 most diverse strains belonging to Lacticaseibacillus spp. to be phenotypically characterized. The strains were tested for their growth performance in milk in combination with the application of technological stresses, for their ability to produce volatile compounds after their growth in milk, and for their ability to use different nutrient sources and resist chemicals. The complex characterization qualified the strains 5959_Lbparacasei and 5296_Lbparacasei as the best candidates to be used as adjunct strains in the production of raw milk and long-ripened cheeses, provided that antibiotic resistance is measured before their employment. Other strains with interesting aromatic capabilities but lower heat resistance were 5293_Lbparacasei, 5649_Lbparacasei and 5780_Lbparacasei, which could be candidates as adjunct strains for uncooked cheese production.

Associations between the Bacterial Composition of Farm Bulk Milk and the Microbiota in the Resulting Swedish Long-Ripened Cheese.

The maturation of a traditional Swedish long-ripened cheese has shown increasing variation in recent years and the ripening time is now generally longer than in the past. While the cheese is reliant on non-starter lactic acid bacteria for the development of its characteristic flavour, we hypothesised that the observed changes could be due to variations in the microbiota composition and number of bacteria in the raw milk used for production of the cheese. To evaluate associations between microbiota in the raw milk and the resulting cheese, three clusters of commercial farms were created to increase variation in the microbiota of dairy silo milk used for cheese production. Cheese production was performed in three periods over one year. Within each period, milk from the three farm clusters was collected separately and transported to the cheese production facility. Following pasteurisation, the milk was processed into the granular-eyed cheese and matured at a dedicated cheese-ripening facility. For each cheese batch, farm bulk and dairy silo milk samples, a starter culture, early process samples and cheese samples from different stages of maturation (7-20 months) were collected and their microbiota characterised using 16S rRNA amplicon sequencing. The microbiota in the farm bulk milk differed significantly between periods and clusters. Differences in microbiota in dairy silo milk were observed between periods, but not between farm clusters, while the cheese microbiota differed between periods and clusters. The top 13 amplicon sequence variants were dominant in early process samples and the resulting cheese, making up at least 93.3% of the relative abundance (RA). Lactococcus was the dominant genus in the early process samples and, together with Leuconostoc, also dominated in the cheese samples. Contradicting expectations, the RA of the aroma-producing genus Lactobacillus was low in cheese during ripening and there was an unexpected dominance of starter lactic acid bacteria even at the later stages of cheese ripening. To identify factors behind the recent variations in ripening time of this cheese, future studies should address the effects of process variables and the dairy environment.