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Abstract
The aim of this study was to isolate lactic acid bacteria (LAB) from artisanal cheeses and evaluate their probiotic potential and antibiotic susceptibility under in vitro conditions. Cheeses obtained at different maturation times were analysed for moisture and lipid contents, as well as for the presence of various microorganisms, including coagulase positive staphylococci, Salmonella spp., Escherichia coli, Listeria monocytogenes, filamentous fungi, yeasts, total mesophilic bacteria, and LAB. After identification, the selected LAB were subjected to human gastrointestinal tract (HGT) conditions to evaluate their survival rates. Of the 18 Lactobacillus strains isolated, 11 survived the HGT test and presented γ-haemolysis. No resistance was observed against antibiotics. Lactobacillus fermentum C1a, C1b, C1c, and C1f, as well as Lactobacillus paracasei C1d, C1e, and C1g, were identified as potential starter cultures for the food industry.
Abstract
Obesity and other unhealthy behaviors are behind cardiovascular morbidity and mortality, with the Roma population particularly at risk. The aim of our cross-sectional (questionnaire- and physical measurements-based) study was to compare the prevalence of obesity in Hungarian, Romanian, and Slovakian Hungarian-speaking Roma and non-Roma (N = 1893) in relation to lifestyle-related risk factors for cardiovascular diseases (CVD). In the total sample, the proportion of extreme obesity was higher in Roma (P < 0.001) than non-Roma. The mean waist circumference was the highest in Hungary (P < 0.001). Visceral fat was higher in the Hungarian Roma sample than in the Slovak (P = 0.006) or Romanian Roma samples (P = 0.005). Hungarian Roma total cholesterol levels were lower than in the Slovak (P < 0.001) or Romanian samples (P < 0.001). Hypertension and cholesterol levels were associated with a higher risk among non-Roma men (P < 0.001), and the presence of smoking increased CVD risk among both men (P = 0.024) and women (P < 0.001) in the Roma minority. The combined presence of several risk factors was found mainly in Roma. Overall, Roma scores were found to be worse, but ethnicity did not provide clear evidence for the questions examined, but rather the level of education, which is associated with socioeconomic status.
Abstract
Radio frequency (RF) heating of agri-food, especially low moisture viscous sauces (LMVS), have obvious advantages. However, uneven heating is one main problem of RF heating technology that has to be solved. Due to the unclear heating mechanism and the difficulty to measure the three-dimensional temperature distribution in the heated object, computer-aided analysis method was adopted. Based on the RF heating numerical calculation model after experimental verification and the characteristics of polyetherimide (PEI) assisted RF heating of peanut butter (PB), this study proposed an improved method for an existing protocol. Meanwhile, parameters of the new protocol were optimised by the Multi-objective Global Optimisation (MGO) of its surrogate model. Results demonstrated that the best size of PEI block in the new protocol was Φ100 × 9.5 mm and the positional height was 12 mm. When the pasteurisation temperature Tp was set to 70 °C and the control temperature Tc was set to 75 °C, the temperature uniformity evaluation indices, Over-shoot Temperature Control Index (OTCI) and Targeted Penetration Depth (TPD), were 0.920% and 3.975 mm, respectively. Compared with 4.845% and 4.940 mm before improvement, the new protocol achieved significant optimisation and improved the temperature uniformity effectively. This also proved the feasibility of MGO method of surrogate model in relevant studies.
Abstract
In the present study, six different edible coatings were evaluated to assess their microbicidal efficiency on pre-treated disinfected fresh cut guava. Among all coatings viz. alginate, pectin, carboxy methylcellulose, carrageenan, and starch, chitosan showed significant microbial growth inhibition and preservation of physico-chemical characteristics of fresh cut guava. Further, optimisation of coating parameters i.e. concentration (% w/v) and dipping time (min) was performed using Response Surface Methodology. It revealed that the fresh-cut guava dipped in 1% (w/v) chitosan for 3 min had desirability level of 91% and extension of its shelf life up to 9 days, as compared to 5 days shelf life of uncoated fresh-cut guava, maintaining all its physico-chemical parameters and microbial growth under the permissible level. Validation of optimised conditions was conducted at 5.0 kg scale that resulted in firmness of 1.90 (kg), 2.6 g/100 g sugars content, 8.0 °Brix total soluble solids content, 3.4 pH, 4.1 log CFU g−1 total plate count, 3.1 log CFU g−1 yeast and moulds count, and 3.1 log CFU g−1 total coliforms count on fresh-cut guava at 9th day of refrigeration storage. Shelf life analysis revealed that chitosan coated fresh cut guava can stay fresh till 10th day under refrigeration with maintaining all its nutritive, microbiological, and sensory properties in the acceptable range.
Abstract
Listeria monocytogenes is able to form biofilms on food contact surfaces. Effectiveness of salt concentration, pH, and temperature on the formation of L. monocytogenes biofilms was evaluated individually and in combinations using microtiter plate assay by measuring the optical density. The tested strains differed in their biofilm formation (low, moderate, and strong) ability. At 37 °C, decreasing amounts of biofilms was observed in almost all L. monocytogenes strains when the NaCl concentration increased from 0.05 to 15%, but all strains were able to form biofilm even at 1 °C. There was no significant difference in biofilm formation between pH 4, 5, and 6, except for some strains. When stress conditions were tested in combination, the addition of 15% NaCl significantly inhibited the growth of L. monocytogenes at 1 °C and 4 °C, and the weak biofilm-forming strains were less sensitive to the temperature and to NaCl treatments than the strong biofilm-forming strains. These results enhance our knowledge of the application of NaCl, temperature, and pH stresses in the food industry and provide basis to develop new strategies for control of biofilm formation of this pathogen.
Abstract
In this study, 25–25 milk samples (25 colostral and 25 mature) collected at different lactational stages were used to analyse the fatty acid composition of breast milk. A gas-chromatographic method was used to perform and analyse the transmethylation of total milk lipid extracts. The milk samples contained 20 different fatty acids. Palmitic acid (C16:0), stearic acid (C18:0), myristic acid (C14:0), oleic acid (C18:1n-9), and linoleic acid (LA, C18:2n-6) were the major components of total lipid, phospholipid (PL), and triacylglycerol (TAG) fractions. Colostrum had a lower percentage of polyunsaturated fatty acids (PUFAs), a higher percentage of saturated fatty acids (SFAs), and a lower level of eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3) in total lipid than mature milk. Triacylglycerol and PL fractions between colostrum and mature milk samples did not differ statistically.
Abstract
Measurement of phenolics, colour parameters, and volatile compounds in wines were made from two varieties of table grapes (‘Zaoheibao’ and ‘Summer Black’) using five pretreatment methods (cold maceration, freezing grapes, lower maturity, fermenting grape juice without skin, and adding tartaric acid) and a control treatment. The effect of the pretreatment methods on the quality of wines was assessed using oenological parameters analysis and volatile compounds analysis. The results indicated that the freezing grape and cold maceration pretreatments improved the colour and increased the contents of phenolic and volatile compounds compared with the control, and freezing was considered to be the most suitable pretreatment method for ‘Zaoheibao’ wine. With respect to ‘Summer Black’ wines, cold maceration and lower maturity were considered to be suitable. Cold maceration enhanced the contents of phenolic and volatile compounds, while lower maturity increased the contents of volatile compounds and total acid. Our results provide new insights into the use of table grapes to make different styles of wine.
