Journal of Dairy Research最新文献

In this research article, response surface methodology (RSM) based optimization of three production parameters namely temperature, time and amount of starter culture of Vechur cow milk yoghurt (VCMY) on the basis of sensory evaluation responses comparing cross-bred cow milk yoghurt (CCMY) as the control is reported. The optimized values of production parameters were 2.15 per cent rate of inoculation, 42°C incubation temperature and 4 h incubation period. The optimized product exhibited significantly lower syneresis, a*, b* values and higher L* values than CCMY. Physico-chemical, microbiological, textural and sensory properties of both VCMY and CCMY during room temperature and refrigerated storage were assessed daily until the onset of spoilage (room temperature) or at five day intervals over a period of 15 d (refrigerated). Both room temperature stored products were graded undesirable by the sensory panel upon one day of storage. Significant reduction was observed in the fat, SNF, total solids, protein and pH content and all the tested colour parameters of the optimized product during refrigerated storage. Total viable counts as well as yeast and mould counts and lactic acid bacteria counts of both VCMY and CCMY progressively increased over the 15 d of storage. Significant reductions were observed in the flavour (P < 0.01), body and texture, colour and appearance and overall acceptability (P < 0.05) scores of both the samples over a period of 15 d. During storage, hardness and adhesiveness values showed an increasing trend whereas the cohesiveness showed a decreasing trend. Storage studies revealed significant differences in the acidity, pH, syneresis, tyrosine value, colour parameters and sensorial attributes of both the yoghurt samples. During the 15 d refrigerated storage period, the VCMY exhibited superior technological attributes to CCMY in terms of lower syneresis %, acidity, microbial population, firmer and less cohesive texture, better flavour, colour and appearance scores. Being the first comprehensive study on the utilization of Vechur cow milk for the preparation of yoghurt, the data generated in the current study would provide a solid base for the exploration of fermentation as a means of value addition of milk of this very rare indigenous cattle breed.

We compared the effects of two waste-based culture media (M1 and M2) on the technological properties of Lacticaseibacillus paracasei 90 (L90) for its application as a secondary culture in Cremoso cheese. The following parameters were studied at different ripening times: pH (7, 20, and 40 d), microbiological counts, carbohydrates and organic acids (7 and 40 d), moisture, fat, protein and volatile compounds (40 d). The viability and the metabolic performance of the strain in cheeses were also verified along ripening. Lactobacilli counts in experimental cheeses manufactured with L90 were ~8 log CFU/g at 40 d, meanwhile adventitious lactobacilli reached ~4 log CFU/g in the control cheese (made without L90). The levels of lactic acid, citric acid and pyruvic acid were similar among cheeses at 40 d, reaching levels of ~1433 mg/100 g, ~172 mg/100 g, and 7 mg/100 g, respectively. However, the concentration of lactic acid showed numerical differences between experimental and control cheeses. The cheeses made with the adjunct culture showed lower residual galactose (< 588 mg/100 g) in comparison with the control cheese (836 mg/100 g), highlighting the potential of L90 to play a bioprotective role. In the same vein, orotic and hippuric acids were metabolized at different degrees in cheeses made with L90, reaching levels of < 3.7 mg/100 g and < detection limit, respectively, at 40 d. In general, volatile compounds profiles were not negatively affected by the culture media used. On the contrary, the production of key aroma compounds (diacetyl and acetoin) was positively affected by the growth of L90 in these alternative media. The results demonstrated that the L90 strain could be used as an adjunct culture in Cremoso cheese, regardless of the culture media employed for its growth.

This research paper focuses on enrichment of yoghurt containing probiotic Lactobacillus casei with persimmon (Diospyros kaki) powder in concentrations of 0 (Control) and then 0.5, 1.0, 1.5 and 2.0% (A-D respectively) and determination of some characteristics of the product during refrigerated storage for 21 d. Powder addition affected the color characteristics, textural properties, titratable acidity and water-holding capacity values. The viability of both yoghurt bacteria (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus) and L. casei increased proportionally to adding persimmon powder for all storage days. Furthermore, addition of fruit powder increased short-chain fatty acid and polyunsaturated fatty acid contents. According to sensory analysis results, sample D had the lowest scores from the panelists, whereas the Control together with samples B and C were the most liked yoghurts in terms of flavor characteristics. In terms of overall acceptability, all of the samples received scores over three points on a five-point scale throughout storage. This study indicates that persimmon powder enriched yoghurt is a good vehicle for L. casei and yoghurt bacteria with improved fatty acid profile and acceptable sensory characteristics.

We aimed to determine the efficacy of different post-milking teat dips in the prevention of intramammary infection and teat condition scores in common crossbred cows (Holstein Frisian × Tharparkar) found in Indian sub-tropical conditions. Eighty healthy crossbred cows were selected and randomly divided into four groups: untreated control, 1% w/v iodine, 5% v/v lactic acid and finally essential oil mix (eucalyptus, lavender, peppermint, and tea tree oils). Samples were collected quarter-wise (n = 308). Sampling as well as teat scoring was done simultaneously. 1st sample was collected before starting teat dipping, followed by 15th day in milk (DIM), 45th DIM and 90th DIM, respectively. The study found that post-milking teat dipping significantly reduced the mean California mastitis test score, somatic cell count and electrical conductivity of the milk in the treatment groups compared to the control group, and also improved milk yield in the treatment groups. There were no differences between the individual treatments. The study also found a significant reduction in teat end condition and teat skin condition after 90 d of post-milking teat dipping.

This Research Communication set out to (1) evaluate the behaviour and performance of dairy calves raised on pasture individually or in groups, and (2) evaluate the influence of physical enrichment on the behaviour and performance of dairy calves raised in groups on pasture. Although there was no difference in grazing behaviour when housed in groups, calves spent longer eating concentrate, ruminating and drinking water. Additionaly, calves housed individually spend part of their time trying to get close to a neighbouring calf. When available, the brush was the physical enrichment item most used by calves followed by straw-man and ball. Pasture access may allow calves to exhibit their highly motivated natural behaviours such as grazing and rumination. Furthermore, social housing provides dairy calves an opportunity for social bonding. Thus, social housing with free access to pasture areas could be an alternative in tropical regions to the typical individual rearing system used in intensive dairy farming.

This research communication aimed at assessing the microbial quality and preparation practices of dahi/thayir, a popular traditional fermented milk product, in households from two distinct agroecological zones in Kerala, India, namely the high-range and central midland, We highlighted the significant variations and potential food safety concerns associated with regional differences in production methods. The local climate significantly influenced the incubation temperature of dahi/thayir, thereby influencing the types of microflora involved in the fermentation process. Data on preparation practices and sensory preferences were collected from producers during the sampling process, covering 200 households. There were significant variations in preparation practices between the two regions, particularly concerning the type of container used, inoculation rate and incubation period. Samples from the high-range region exhibited significantly higher acidity and coliform count as well as yeast and mold count than the central midland region. The household fermentation of milk is often uncontrolled, causing increased acidity levels. This uncontrolled fermentation favored the growth of contaminants such as coliforms and yeast, posing a potential threat to food safety. This study underscores the importance of understanding microbial quality variations and preparation practices in dahi/thayir production, emphasizing the need for proper fermentation techniques and hygienic practices to ensure the safety and quality of this traditional fermented milk product.

The continuing emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be ameliorated by infection prevention through daily diet. In this study, we examined the anti-SARS-CoV-2 activity of 10 commercially available dairy products. They did not show any cytotoxicity against VeroE6/transmembrane protease serine 2 (TMPRSS2) cells (CC₅₀ > 4 mg/ml). Importantly, these cells were checked using the cytopathic effect (CPE) assay, and 4 mg/ml dairy products reduced virus-induced CPE by more than 30%. Notably, Icreo akachan milk, an infant formula, showed the highest antiviral activity with an IC₅₀ of 1.4 mg/ml. We assessed the effects of the dairy products on the entry of SARS-CoV-2 pseudovirus. R1 and Yakult, lactic acid bacterial beverages, inhibited viral entry with IC₅₀ of 2.9 and 3.5 mg/ml, respectively. Collectively, these results indicate that commercially available dairy products moderately inhibit SARS-CoV-2 infection and may reduce the incidence of viral infections.

The aim of this research was to investigate the ability of an in vitro simulated gastrointestinal digestion (SGID) to generate peptides from bovine lactoferrin (LF) that possess antibacterial activity. Escherichia coli was examined as the target pathogen due to its prevalence in foods and the well-documented antibacterial effect of both LF and LF peptides against this organism. Results showed that in-vitro digested LF, specifically gastric LF digesta, exhibited significant antibacterial activity at low concentrations against E. coli compared to its undigested counterpart. Additionally, the highest antibacterial activity in the gastric digesta was associated with a relatively high molecular weight fraction of >30 kDa obtained within the first 30 min of the SGID. This demonstrates that the digestive process can result in the generation of antibacterial LF peptides and contribute to improving the antimicrobial properties of LF exhibited in its undigested state, making it a suitable dairy food additive to potentially provide protection against bacterial pathogens within the gastrointestinal system.

An attempt was made to develop a novel dairy-based dip-like product from heat-acid-induced milk gel and whey. Based upon preliminary trials, the combination of cream (15-35%), whey (60-70%) and common salt (0.8-1.0%, all three as weight of heat-acid-induced milk gel) was selected for optimization of the dairy dip through factorial design of response surface methodology (RSM). Addition of glycerol monostearate, trisodium citrate and sodium hexametaphosphate each at the rate of 0.3% (as weight of heat-acid-induced milk gel) in the formulation was previously standardized. The optimization was carried out by analysing the textural and sensorial parameters of the dairy-based dip. The sensorial parameters (flavour, body and texture, colour and appearance and overall acceptability) and textural parameters (firmness, stickiness, work of shear and work of adhesion) were significantly (P < 0.05) correlated with the ingredient formulation. RSM analysis suggested the use of cream, whey and common salt at amounts of 27.92, 60.26 and 0.8% of the weight of heat-acid-induced milk gel for preparing dairy-based dip with a desirability of 0.84. The formulated product contained a lower fat but higher protein and lactose content than cheese dip.