Mixed Starter Cultures Research Articles

Metabolic footprint analysis of metabolites that discriminate single and mixed yeast cultures at two key time-points during mixed culture alcoholic fermentations.

There has been a growing interest towards creating defined mixed starter cultures for alcoholic fermentations. Previously, metabolite differences between single and mixed cultures have been explored at the endpoint of fermentations rather than during fermentations. To create metabolic footprints of metabolites that discriminate single and mixed yeast cultures at two key time-points during mixed culture alcoholic fermentations. 1H NMR- and GC-MS-based metabolomics was used to identify metabolites that discriminate single and mixed cultures of Lachancea thermotolerans (LT) and Saccharomyces cerevisiae (SC) during alcoholic fermentations. Twenty-two metabolites were found when comparing single LT and mixed cultures, including both non-volatiles (carbohydrate, amino acid and acids) and volatiles (higher alcohols, esters, ketones and aldehydes). Fifteen of these compounds were discriminatory only at the death phase initiation (T1) and fifteen were discriminatory only at the death phase termination (T2) of LT in mixed cultures. Eight metabolites were discriminatory at both T1 and T2. These results indicate that specific metabolic changes may be descriptive of different LT growth behaviors. Fifteen discriminatory metabolites were found when comparing single SC and mixed cultures. These metabolites were all volatiles, and twelve metabolites were discriminatory only at T2, indicating that LT-induced changes in volatiles occur during the death phase of LT in mixed cultures and not during their initial growth stage. This work provides a detailed insight into yeast metabolites that differ between single and mixed cultures, and these data may be used for understanding and eventually predicting yeast metabolic changes in wine fermentations.

Mixed Starter Culture Regulates Biogenic Amines Formation via Decarboxylation and Transamination during Chinese Rice Wine Fermentation.

The utilization of amine-negative starter based on an understanding of nitrogen metabolism is a useful method for controlling biogenic amine (BA) in Chinese rice wine (CRW) fermentation. The contribution of brewing materials to protein degradation was analyzed; wheat Qu protein had no effect, and yeast autolysis generated 10% amino nitrogen. Milling degree of rice was strongly correlated with BAs formation ( R2 = 0.99). Subsequently, Lactobacillus plantarum and Staphylococcus xylosus were coinoculated as amine-negative starter at an optimized ratio of 1:2. Coinoculation induced a significant reduction in total BAs (43.7%, 44.5 mg L-1), putrescine (43.0%, 20.4 mg L-1), tyramine (42.8%, 14.3 mg L-1), and histamine (42.6%, 3.5 mg L-1) content. Notably, BAs degradation ability of Staphylococcus xylosus was stronger than the suppression effect of Lactobacillus plantarum, and higher lactic acid bacteria (LAB) amount has a positive correlation with lower BAs content. Overall, mixed strains exerted a synergistic effect in lowering BAs accumulation via decarboxylation and transamination.

Dynamics and diversity of microbial community succession during fermentation of Suan yu, a Chinese traditional fermented fish, determined by high throughput sequencing

The main goal of this study was to investigate the dynamics, diversity and succession of microbial community present during the preparation of Suan yu (fermented fish), with and without starter cultures by high-throughput sequencing of 16S rRNA and ITS1 genes. Firmicutes and Ascomycota were the predominant phyla of bacteria and fungi, respectively, in all samples. At the genus level, Lactobacillus, Macrococcus and Staphylococcus were the predominating bacteria throughout the fermentation process, regardless of the inclusion of starter cultures. Saccharomyces was the predominating fungal genus in the early-fermentation stage of samples that inoculated starter cultures (MS), while the final product was dominated by Candida and Wickerhamomyces. Compared with naturally-fermented samples (NS; no starter cultures), Lactococcus, Leuconostoc, Enterococcus, Vibrio, Fusicolla and Torulaspora were inhibited and Aureobasidium emerged in samples inoculated with starter cultures (P < .05). Unweighted pair-group and principal component analyses of bacterial and fungal compositions revealed that microbiota structures differed between NS and MS samples. Redundancy analysis indicated that water content and pH might be important factors influencing the dominant bacterial and fungal community. Results indicated that microbial community were dynamic during fermentation process and the inoculation of mixed starter culture inhibited the growth of many organisms associated with food spoilage and contributed to the improvement of the quality of Suan yu products.

Phospholipid molecular species composition of Chinese traditional low-salt fermented fish inoculated with different starter cultures

Phospholipid molecular species composition of Chinese traditional low-salt fermented fish (Suan yu) inoculated with different starter cultures was investigated. Fifty-six molecular species of phospholipid including 20 species of phosphatidylcholine (PC), 15 species of phosphatidylethanolamine (PE), 6 species of phosphatidylserine (PS), 9 species of lysophosphatidylcholine (LPC), and 6 species of lysophosphatidylethanolamine (LPE) were identified using ultra-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). PC (C16:0–C18:1), PE (C16:0–C22:6), PS (C15:0–C22:6), LPC (C22:6) and LPE (C22:5) were the predominant species. Bioactive polyene phospholipids mainly existed in PE. Furthermore, starter cultures exhibited different influence on phospholipid molecular species. Compared to naturally fermented Suan yu, more molecular species of PE and PS as well as polyene phospholipids were detected in the samples inoculated with Saccharomyces cerevisiae 31 and mixed starter cultures.

Process Standardization for the Manufacture of Shrikhand Spread

Purpose: Shrikhand Spread, a unique sweetened fermented Indian milk product is made by separation of whey from dahi, the Indian counterpart of Western yoghurt, followed by addition of sugar. Production of dahi employing traditional method involved undefined mixed starter cultures, uncontrolled fermentation and longer production time resulting in wide variation in its chemical and microbiological qualities. In order to cater to a product with desirable properties like lower post-acidification, higher flavour profile, firm body and lower syneresis coupled with shorter production time, conjugated application of yoghurt cultures and dahi cultures were tried. Since the shelf-life of dahi is limited, conversion into shrikhand spread may be used as a tool to extend the shelf-life and therefore the market reach towards commercialization into the global market as a potential functional food. Design/Methodology/Approach: Different batches of dahi were made from homogenized (Stage I - 2500 psi, Stage II - 500 psi) and pasteurized (74-78 °C/16-19 Sec) milk, pre-adjusted to 3.15-3.20% fat and 11.40% snf with diverse starter combinations selected upon the extent of post acidification, volatile acid production, syneresis and rheological characteristics. Homogenized, pasteurized and regulated milk was further subjected to a heat-treatment (90°C/10 min) and seeded with selected starter combinations to obtain firm curd intended for shrikhand spread manufacture. Shelf-life of shrikhand spread was evaluated in terms of chemical and microbiological criteria upto 7 days of storage at 8±1°C. Findings: Starter combination of eXactDahi 2+YoFlex Express 1.0 at an incubation temperature-time combination of 45°C/5h was found most suitable for producing dahi with smooth body, higher volatile acidity and low syneresis. Utilization of dahi obtained employing the above starter combination for the manufacture shrikhand spread was suggested and the product was found to retain its goodness when stored for 7 days at 8±1°C. Originality/Value: Conjugated use of yoghurt cultures with dahi cultures was suggested to overcome the drawbacks of traditional process of dahi manufacture suitable for conversion into shrikhand spread. This dahi was found capable of enhancing its dietetic value in addition.

Characterization of Cantonese sausage fermented by a mixed starter culture

L. plantarum, P. pentosaceus, and D. hansenii isolated from Cantonese sausage were investigated for their potential as a mixed starter culture with the capability to improve sausage quality. Results unveiled that Cantonese sausage produced with the mixed starter culture exhibited low nitrite residue and low-fat content advantages over fermented sausage without starter culture. Different fermentation time possessed different influence on physicochemical parameters, free amino acids (FAAs) composition and textural characteristics of Cantonese fermented sausage. Within 24 hrs fermentation, Cantonese sausage fermented by the mixed starter culture enjoyed soft texture with relatively high titratable acidity (6.98 ± 0.02 g/kg), FAAs contents (1,893.2 mg/100 g dry basis) and low nitrite residue (33.3 ± 0.15 mg/kg). These findings indicated that the combination of those strains could be used as a mixed starter culture for Cantonese fermented sausage. Practical applications Cantonese sausage is one of the most popular Chinese-style cured meat products. However, ripening process of traditional sausages belongs to fermentation without starter culture, which hardly guarantees product quality and safety. This study provides a novel mixed starter culture for sausage production and results verified its priority over improving sausage quality.

Characterization of the killer toxin KTCf20 from Wickerhamomyces anomalus, a potential biocontrol agent against wine spoilage yeasts

Wickerhamomyces anomalus Cf20 secretes the killer toxin KTCf20 that inhibits several wine spoilage yeasts of the species Pichia guilliermondii, P. membranifaciens, Brettanomyces bruxellensis and Dekkera anomala. KTCf20 binds cell wall extracts from the sensitive target P. guilliermondii Cd6; however, this capacity was lost when cell wall extracts were pre-treated with fungal β-glucanase. Pustulan and laminarin inhibited killer activity, suggesting that β-1,3 and β-1,6-glucans may be the putative binding sites for KTCf20 on the cell wall of sensitive cells. The toxin was produced and showed to be stable and highly active at physicochemical conditions suitable for winemaking process. In addition, the strain Cf20 is compatible with Saccharomyces cerevisiae in co-culture conditions being potential its application in a mixed starter culture. These data suggest that W. anomalus Cf20 and/or KTCf20 are promising biocontrol agents against spoilage yeasts during wine-making process.

Selection of starter cultures for the production of sour cassava starch in a pilot-scale fermentation process.

Sour cassava starch (Polvilho azedo) is obtained from a spontaneous fermentation conducted by microorganisms from raw materials and fermentation tanks. This product is traditionally used in the baking industry for the manufacture of biscuits and Brazilian cheese breads. However, the end of fermentation is evaluated empirically, and the process occurs without standardization, which results in products of inconsistent quality. Predominant microbiota from a cassava flour manufacturer was isolated in order to select starter cultures for the production of sour cassava starch in a pilot-scale fermentation process. Lactic acid bacteria and yeasts were isolated, enumerated and grouped by Restriction Fragment Length Polymorphism, and PCR fingerprinting, respectively. One isolate of each molecular profile was identified by sequencing of the rRNA gene. LAB were prevalent throughout the entire process. Lactobacillus brevis (21.5%), which produced the highest values of acidity, and Lactobacillus plantarum (13.9%) were among the most frequent species. Pichia scutulata (52.2%) was the prevalent yeast and showed amylolytic activity. The aforementioned species were tested as single and mixed starter cultures in a pilot-scale fermentation process for 28 days. L. plantarum exhibited better performance as a starter culture, which suggests its potential for the production of sour cassava starch.

Selection of Leuconostoc strains isolated from artisanal Serrano Catarinense cheese for use as adjuncts in cheese manufacture.

Serrano Catarinense cheese is a raw bovine milk cheese produced in the region of Santa Catarina, Brazil. Twelve representative strains of Leuconostoc isolated from 20 samples of this artisanal cheese were selected and submitted for evaluation of the acidifying, proteolytic, autolytic, aminopeptidase and lipolytic activities, NaCl and acid resistance, production of dextran and biogenic amines and antimicrobial activity. The aim was to genetically and technologically characterize the Leuconostoc strains in order to use them in mixed starter cultures for cheese manufacture. Leuconostoc mesenteroides subsp. mesenteroides was the species that accounted for the largest proportion of isolates of Leuconostoc genus. Two leuconostoc isolates stood out in the acidifying activity, with reduction in pH of 1.12 and 1.04 units. The isolates showed low proteolytic and autolytic activity. Most of the isolates were dextran producers, presented good resistance to the salt and pH conditions of the cheese and showed antimicrobial activity against cheese pathogen bacteria, and none of them produced biogenic amines. These results allowed the selection of five strains (UEL 04, UEL 12, UEL 18, UEL 21 and UEL 28) as good candidates for use as adjunct cultures for cheese manufacture. © 2018 Society of Chemical Industry.

Schizosaccharomyces japonicus: A Polysaccharide-Overproducing Yeast to Be Used in Winemaking

Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces japonicus #13 were inoculated in commercial grape must, and the impact of different inoculum ratios (1:1; 1:100; 1:10,000) on growth and fermentation kinetics and on the analytical profiles of the experimental wines was here evaluated. Results obtained showed that S. japonicus #13 affects S. cerevisiae growth and fermentative capability only for S. cerevisiae/S. japonicus inoculum ratio 1:10,000. The analytical profiles of the wines produced by mixed starter cultures indicated that this non-Saccharomyces yeast modulates the concentration of malic and acetic acids and of some of the most important volatile compounds, such as β-phenyl ethanol, in an inoculum-ratio-dependent fashion. Moreover, all experimental wines obtained with S. japonicus #13 in mixed cultures reached concentrations of total polysaccharides significantly higher than those obtained with pure cultures of S. cerevisiae EC1118, and total polysaccharides increased with the increase of S. japonicus #13 cell concentration. Based on these results, S. japonicus #13 might be profitably inoculated in combination with S. cerevisiae EC1118 to enhance wine complexity and aroma and to improve wine stability by increasing the final concentration of polysaccharides.

Isolation, Biochemical Characterization and DNA Identification of Yogurt Starters &amp;lt;i&amp;gt;Streptococcus thermophilus&amp;lt;/i&amp;gt; &amp;amp; &amp;lt;i&amp;gt;Lactobacillus delbrueckii ssp. bulgaricus&amp;lt;/i&amp;gt; in Gaza Strip

Background: Milk is a healthy human nutrient, which is fermented to yogurt by lactic acid bacteria, mainly Streptococcus salivarius ssp, thermophilus and Lactobacillus. delbrueckii ssp. bulgaricus. This study aimed to isolate thermophilic starter bacteria from homemade yogurt made in Gaza Strip. The study sought to define both the biochemical and molecular characteristics of the isolated bacteria. Results: Three of the isolates were identified as Streptococcus thermophiles while two isolates were recognized as Lactobacillus delbrueckii ssp. bulgaricus. All five identified isolates showed worthy acidification capacity. Based on these characters, strains were applied for making yogurt either as single pure cultures or as mixed cultures. When using mixed cultures from S. thermophiles and L. bulgaricus, all tested combinations showed positive results. Conclusion: Isolated strains showed remarkable biotechnological characters. The isolates are expected to stimulate and improve quality of the yogurt when they are used as mixed starter cultures.

Effect of microbial fermentation enhance the flavor of beef flavoring

Beef paste flavoring were manufactured from minced beef bone, by high pressure extraction followed by enzyme hydrolysis,after which fermentation processes were introduced to expect a better flavor, and Maillard reaction. Beef paste flavoring were divided into to 5 groups in terms of fermentation processes:control group,without any starter culture; WBL-45 group,inoculated with WBL-45 mixed starter culture (Staphylococcus aureus + Staphylococcus xylose + Lactobacillus sake); WBX-43(Staphylococcus aureus + Staphylococcus xylose); BOM-13(Lactobacillus sake); THM-17 (Staphylococcus xylose + Pentose phosphate). After 30℃ fermentation for 12 h, Maillard reactions led to the final beef flavoring. Sensory evaluation combined with electronic nose and electronic tongue were used to analyze the volatile odor and taste components.The results showed that fermented samples had quite different and better odor and taste component patterns, compared to the control sample.According to the comprehensive analysis results of four beef flavorings were treated with different strains,beef flavoring manufactured with THM-17 was the best among all the samples, with the most different smell and taste patterns from the control samples(maximum p<0.05).The results proved that microbial fermentation has the ability to enhance odor and taste of beef flavoring,which provide a new idea for the industrialized production of seasoning.

Segregation of Tetragenococcus halophilus and Zygosaccharomyces rouxii using W1/O/W2 double emulsion for use in mixed culture fermentation

Antagonism in mixed culture fermentation can result in undesirable metabolic activity and negatively affect the fermentation process. Water-oil-water (W1/O/W2) double emulsions (DE) could be utilized in fermentation for segregating multiple species and controlling their release and activity. Zygosaccharomyces rouxii and Tetragenococcus halophilus, two predominant microbial species in soy sauce fermentation, were incorporated in the internal W1 and external W2 phase of a W1/O/W2, respectively. The suitability of DE for controlling T. halophilus and Z. rouxii in soy sauce fermentation was studied in relation to emulsion stability and microbial release profile. The effects of varying concentrations of Z. rouxii cells (5 and 7logCFU/mL) and glucose (0%, 6%, 12%, 30% w/v) in the W2 phase were investigated. DE stability was determined by monitoring encapsulation stability (%), oil globule size, and microstructure with fluorescence and optical microscopy. Furthermore, the effect of DE on the interaction between T. halophilus and Z. rouxii was studied in Tryptic Soy Broth containing 10% w/v NaCl and 12% w/v glucose and physicochemical changes (glucose, ethanol, lactic acid, and acetic acid) were monitored. DE destabilization resulted in cell release which was proportional to the glucose concentration in W2. Encapsulated Z. rouxii presented higher survival during storage (~3 log). The application of DE affected microbial cells growth and physiology, which led to the elimination of antagonism. These results demonstrate the potential use of DE as a delivery system of mixed starter cultures in food fermentation, where multiple species are required to act sequentially in a controlled manner.

Promotion of Early Gut Colonization by Probiotic Intervention on Microbiota Diversity in Pregnant Sows.

The aim of this work was to design a novel mixed probiotic culture for piglets and to evaluate its beneficial effect on the piglets’ gut health. The possible mechanisms of probiotic activity, such as adhesion, competitive pathogen exclusion and influence on gut microbiota diversity were determined. Mixed probiotic starter culture is composed of three thermophilic lactic acid bacteria (LAB) strains: Lactobacillus helveticus BGRA43, Lactobacillus fermentum BGHI14 and Streptococcus thermophilus BGVLJ1-44. The strains BGVLJ1-44 and BGRA43 showed good technological properties (fast milk curdling, strong proteolytic activity). In addition, the strain BGVLJ1-44 produces exopolysaccharide (EPS), BGHI14 is heterofermentative LAB strain with significant immunomodulatory effect, while the strain BGRA43 showed strong antimicrobial activity against different pathogens and exhibited significantly higher level of adhesion to Caco-2 cells comparing to other two strains. Both lactobacilli strains BGRA43 and BGHI14 (p < 0.05), as well as probiotic combination (p < 0.01) significantly reduced the adhesion of Escherichia coli ATCC25922 to Caco-2 cells, while the strains BGVLJ1-44 (p < 0.01) and BGRA43 (p < 0.05) significantly reduced adhesion of Salmonella 654/7E (veterinary isolate). The results of farm trial revealed that treatment of sows with new fermented dairy probiotic influenced the piglets’ gut colonization with beneficial bacteria and reduced the number of enterobacteriaceae in litters from some treated sows (no significant due to high variability among animals). Finally, this is the first study reporting that the treatment of sows with probiotic combination resulted in the improved microbiota diversity in neonatal piglets.

Selection and use of indigenous mixed starter cultures for mustard leaves fermentation and the improvement of cuocai characteristics

To improve the characteristics and safety of traditional cuocai, the selection and use of mixed starter cultures is important. This study aimed to isolate the main indigenous lactic acid bacteria (LABs) and yeast species from spontaneous fermented mustard leaves, and they were used as starter cultures to ferment mustard leaves. Five predominant LABs, namely Q-1 (Enterococcus faecalis), G-1 (Lactobacillus plantarum), G-3 (Lactobacillus pentosus), and G-2 and G-4 (Lactobacillus buchneri) strains, and the two yeast strains J-1 (Issatchenkia orientalis) and J-2 (Issatchenkia occidentalis) were isolated from cuocai. From the results, Lb. plantarum and I. orientalis strains exhibited strong growth ability, fast acidification, and potent low-pH tolerance. Therefore, they were chosen as the mixed starter cultures to ferment mustard leaves. During the process of culture-dependent fermented mustard leaves, the changes of acidity, total crude protein, and total sugar were similar to those of culture-independent fermented mustard leaves, while the nitrite content of culture-dependent fermented mustard leaves was significantly lower than that of culture-independent fermented cuocai. According to gas chromatography-mass spectrometry analysis, the main volatile flavor compounds of fermented mustard leaves were alcohols, aldehydes, esters, and sulfides. There was no significant difference of volatile flavor compounds between the processes of culture-dependent and culture-independent fermentations. Therefore, it was suggested that Lb. plantarum and I. orientalis strains could be used to ferment cuocai instead of the traditional ferment method to control the quality and shelf safety of cuocai. © 2017 Society of Chemical Industry.

Effect of symbiotic interaction between a fructooligosaccharide and probiotic on the kinetic fermentation and chemical profile of maize blended rice beverages

There is an important demand for the development of new non-dairy probiotic beverages in the functional food market. This work aimed to develop new fermented beverages from maize and rice. Lactobacillus plantarum CCMA 0743, Torulaspora delbrueckii CCMA 0235, and the commercial probiotic Lactobacillus acidophilus LACA 4, were used as a mixed starter culture. Two prebiotic concentrations, 20 and 50g/L fructooligosaccharide (FOS) were tested. The growth of L. acidophilus LACA 4 was favored by 50g/L FOS and after refrigerated storage at 4°C for 28days, its population remained above 107CFU/mL. Lactic and acetic acids were the main organic acids detected, at around 3.7 and 0.5g/L, respectively. Ethanol was present at <5g/L in non-alcoholic beverages. Fifty-five volatile compounds including acids, alcohols, aldehydes, esters, ketones, pyrazines and others, were detected. The sensorial analysis demonstrated that >50% of consumers liked slightly or liked extremely the beverages (scores from 6−9). Therefore, potential symbiotic cereal beverages were successfully obtained using a mix of lactic acid bacteria and yeast as a starter culture. This is an important step in the commercial production of alternative beverages from common food substrates for consumers.

Complete Genome Sequence of Streptococcus thermophilus KLDS 3.1003, A Strain with High Antimicrobial Potential against Foodborne and Vaginal Pathogens.

Lactic acid bacteria play increasingly important roles in the food industry. Streptococcus thermophilus KLDS 3.1003 strain was isolated from traditional yogurt in Inner Mongolia, China. It has shown high antimicrobial activity against selected foodborne and vaginal pathogens. In this study, we investigated and analyzed its complete genome sequence. The S. thermophilus KLDS 3.1003 genome comprise of a 1,899,956 bp chromosome with a G+C content of 38.92%, 1,995 genes, and 6 rRNAs. With the exception of S. thermophilus M17TZA496, S. thermophilus KLDS 3.1003 has more tRNAs (amino acid coding genes) compared to some S. thermophilus strains available on the National Centre for Biotechnology Information database. MG-RAST annotation showed that this strain has 317 subsystems with most genes associated with amino acid and carbohydrate metabolism. This strain also has a unique EPS gene cluster containing 23 genes, and may be a mixed dairy starter culture. This information provides more insight into the molecular basis of its potentials for further applications in the dairy and allied industries.

Antihypertensive Effect of Novel Functional Fermented Milk in Induced High Blood Pressure Rats

The effect of functional fermented milk rich in bioactive peptides on blood pressure, lipid profile, antioxidant status and some organ's in hypertensive-induced rats was studied. Functional fermented milk produced from skimmed milk fortified with 2% SMP:WPC (1:1) and partially proteolyzed by trypsin (2.5 mg/100 g milk for 20 min) before fermintation by using mixed starter culture of Lb. rhamnosus B-1445, O-114, YC-X11 and Lb. helveticusLh-B 02 with a 3:2:1:1 ratio, respectively. The main obtained results showed that the daily administration of functional fermented milk (group 4) for 4 weeks lowered the systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 43 and 9 mmHg, respectively compared with a negative control group which administered saline (group 1). Plasma triglycerides, total cholesterol, atherogenic index and cardiac risk factor reduced in group 4 compared to group 1, while low-density lipoprotein, high-density lipoprotein, antithrombotic activity and antioxidant markers did not differ significantly among all groups. Histologically, there were no significant changes in the liver, kidney, heart and aorta tissues of rats in groups 1 and 4. In contrast, there were histopathological changes in these tissues of rats in group 2 which received daily 2 mg captopril /100 g BW.

Perubahan Komposisi Kimiawi Produk Yogurt dengan Penambahan Kalsium Karbonat pada Kultur Starter Campuran

Mixed lactic acid bacteria culture is commonly used in yogurt production. In the present study, two lactic acid bacteria (Lactobacillus bulgaricus and Streptococcus thermophillus) was used as starter culture. Calcium carbonate was added to the starter culture to increase the quality of mixed starter culture of L. bulgaricus and S. thermophillus with ratio of 4:1. The present study was directed to investigate the chemical composition of mixed starter culture with and without calcium carbonat addition. Furthermore, the effect of each starter culture on yogurt product chemical composition was also examined. The pH, lactose, soluble protein and acid content was determined as chemical composition parameters. For starter culture without calcium carbonate addition, the yogurt has pH, lactose, soluble protein and acid content of 4.18–4.39, 4.18–4.39% w/v, 2.88–4.36% w/v and 0.82–0.99% w/v, respectively. While for starter culture with calcium carbonate addition, the yogurt product has pH, lactose, soluble protein and acid content of 4.26–4.37, 1.47–1.75% b/v, 3.42–4.95% w/v and 0.86–1.11% w/v, respectively. Addition of 0.05% w/v calcium carbonate to mixed starter culture gave effect on lactose consumption, where it still can convert lactose to lactic acid up to 45 days of storage. Furthermore, the yogurt product made with starter culture with calcium carbonate addition has higher soluble protein content compared to yogurt made with starter culture without calcium carbonate addition

Contribution of Mixed Starter Cultures to Flavor Profile of Suanyu - A Traditional Chinese Low-Salt Fermented Whole Fish

The effect of mixed starter cultures isolated from Suanyu on flavor compounds development has been researched. Microorganism, pH, TA, sugars, nonvolatile organic acids and volatile compounds were analyzed in Suanyu with or without starters. In inoculated samples, a higher growth of lactic acid bacteria (LAB) and a declining rate of pH were determined when compared with the controlled samples. Besides, higher levels of volatile compounds were detected in inoculated Suanyu (19342.47, 19852.74 × 106 area units for PS) than those in controlled samples. During the process, aldehydes, acids, alcohols, esters and ketones were formed and increased continuously. Especially in Suanyu with PS, higher levels of ethanol (6973.8, 6549.9 × 106 area units) and acetic acid (2116.8, 2471.1 × 106 area units) were detected, which could produce unique wine flavor and moderate acid taste. Furthermore, high content of hexanal was generated through the addition of PS, which could contribute to a green grass odor. Practical Applications In this study, microorganism, pH, TA, sugars, nonvolatile organic acids and volatile compounds were analyzed in Suanyu with autochthonous starter cultures. The results showed that the generative stability of Suanyu can be assured and the product quality can be advanced by adding autochthonous starter cultures compared with that of noninoculated samples. There is a need to add modern processing technology such as microbial fermentation of the fermentation process to achieve effective control to ensure product flavor and product quality stability. In this study, autochthonous starter cultures isolated from Suanyu, which were propitious to the demand of industrialization. Besides, once the research is applied in the industrialized production, and considerable social and economic benefits can be obtained. Therefore, this study has a good prospect in application.