International Journal of Dairy Technology最新文献

The probiotic Lactiplantibacillus plantarum could not independently ferment milk to form yoghurt. In this study, the effect of Streptococcus thermophilus extract on the acidification and propagation capabilities of L. plantarum during milk fermentation was investigated. The results showed that the addition of S. thermophilus crude cell extract significantly shortened the fermentation time and promoted the propagation of L. plantarum. Moreover, the addition of 0.2% S. thermophilus cell extract resulted in a higher acidification rate (final pH: 4.53) at 72 h of fermentation and a higher L. plantarum cell count (log 8.31 cfu/g) at 24 h of fermentation at 37°C. It was speculated that the presence of amino acids and free nucleotides in S. thermophilus lysate might have played an indispensable role during milk fermentation by L. plantarum. This study provided a novel strategy for utilising L. plantarum to ferment milk without using exogenous food ingredients.

This study investigated the synergistic effects of lactic acid (0.5%, 1% and 2%) and ultrasound (400 W, 20 kHz) on the inactivation of Pseudomonas fluorescens. Combined ultrasound and 2% lactic acid for 5 min reduced the planktonic cell count below 1.40 log cfu/mL. Ultrasound promoted the inactivation of P. fluorescens biofilms by lactic acid and increased the release of ATP and nucleic acids from bacterial cells by 0.09–0.22 μmol/OD and 0.043–0.113 of OD₂₆₀ values, respectively. Results indicated that combined ultrasound and lactic acid can serve as a potential technique to control P. fluorescens biofilms.

As an innovative bio-dairy product, yoghurt was enriched with Spirulina-encapsulated aqueous/hydroalcoholic extracts of pomegranate peel (PP). Some metabolomics, antioxidative, textural and colour properties of bio-yoghurt samples were investigated. The samples with Spirulina (YM) and PP (YPA) had the highest lactic, citric and uric acid. The aroma profile of the samples was affected encapsulation process and storage time. The values on day 1 and day 21 were 17.84–17.04 mg/kg for acetaldehyde, 0.98–0.90 mg/kg for diacetyl and 54.42–46.65 mg/kg for acetoin. The sample with encapsulated PP aqueous extract (YEPA) had the highest TPC (2.97 mg GAE/g), and the sample with PP aqueous extract (YPA) had the highest antioxidant capacity (0.36 mg TE/g). The present study describes that bio-yoghurt enriched with Spirulina-encapsulated PP could be considered a good alternative for consumers demanding functional dairy products and a holistic approach to a circular bioeconomy.

This study aimed to evaluate the presence of Staphylococcus aureus from the production chain of artisanal Coalho cheese, and to analyse the phenotypic profile of the strains, virulence factors and antimicrobial susceptibility profile. From the 52 samples collected, typical colonies of Staphylococcus spp. were isolated. From these positive S. aureus isolates, the genes encoding for enterotoxin production and antibiotic resistance were characterised. Additionally, agr locus typing was also performed. A significant presence of the sea enterotoxin producing gene, a higher incidence of the mecA gene and agr III group was identified. There was multiple resistance to penicillin, oxacillin, erythromycin and clindamycin in 79% of isolates. These results indicate that the artisanal Coalho cheese production process is associated with high contamination levels and significant potential for the isolated strains to produce enterotoxins. Therefore, there is cause for concern regarding the quality of the artisanal Coalho cheese produced.

Investigating the impact of ionic calcium (iCa) on alcohol stability and its correlation with suggested milk classification, a study analysed 379 bulk milk samples collected over 4 months. Results unveiled a significant inverse relationship between iCa concentration and alcohol test stability. Alkaline or unstable non-acidic milk exhibited no disparity in iCa content compared to normal or acidic milks. Despite fluctuations in iCa levels, seasonal variations, not milk classification, better accounted for the changes in stable milk detection in the alcohol test at the 76% setpoint. The seasonal fluctuation in iCa within bulk tank-collected milk carries implications for standardising industrial processes.

In this study, the partitioning of minerals in ultrafiltration (UF) streams of skim milk using cross-flow (CF-UF) and dead-end (DE-UF) was investigated using 50 kDa membrane at different temperatures (5, 10, 25, 35, 55°C). CF-UF showed higher protein retention (6.02–10.9%) compared with DE-UF (3.44–4.70%), along with more retention of calcium, with values ranging from 29.8 to 41.5 and 57.8 to 112 mM for DE-UF and CF-UF, respectively. Ionic calcium in permeates varied less for CF-UF (2.48–1.18 mM) than for DE-UF (3.11–0.98 mM). The insights provided in this study can be exploited to tailor adjustments of minerals in milk streams using UF.

The aim of this study was to investigate lipid oxidation/degradation kinetics of lactic butter manufactured from heat-treated and cultured cream, supplemented with Myrtus communis essential oils and stored at 4°C. Lipid oxidation followed zero-order, while vitamin degradation followed first-order reaction kinetics in fresh lactic butter. Optimising heat treatments of the cream at 70°C and 80°C for 30 s and using M. communis EOs reduced lipid oxidation and α-tocopherol degradation (P ≤ 0.05) of lactic butter samples. It was concluded that M. communis EOs is effective as antioxidant as compared to synthetic ascorbyl palmitate for improving stability of lactic butter.

This study aimed to examine the impact of β-carotene, astaxanthin and phytosterol esters on the colour and oxidative stability of butter, as well as to explore a shelf life prediction method based on colour analysis. The results of correlation analysis indicated a significant linear correlation between acidity and whiteness index and yellowness index, with a linear fit coefficient (r²) exceeding 0.9796. In comparison with traditional shelf life prediction models, this method exhibited an average deviation of only 6.9% in its predicted results. The findings may contribute to the rapid evaluation of the shelf lives of commercial butter products.

Soy protein (SP) and milk protein are nutritionally complementary proteins, while they have different postprandial kinetic manifestations. In this study, different sources of proteins (casein, whey protein and SP isolate) were compounded in different concentrations and ratios. An in vitro dynamic gastrointestinal digestive system for children was used to study the digestive behaviour. For all the concentrations assessed, a consistently high level of small peptide release was demonstrated at 2.67 g/100 mL protein concentration, while the addition of 10% SP isolate would increase the release of small peptides. Overall, the study offers novel perspectives on children's products with diverse protein sources.