Journal of Dairy Research最新文献

A caseinomacropeptide (CMP) concentrate was produced from sweet whey by ultrafiltration (UF) and diafiltration (DF) using polyethersulfone (PES) membrane. Effects of the pH of whey feed and molecular weight cut-off of membrane (9 and 25 kDa) on permeate flux, recovery and purity of CMP were investigated. Before the UF, a pre-heat treatment at 90°C for 1 h and then acifidication to pH of 5 were applied to precipitate the major proteins in sweet whey. The pH value of UF feed was re-adjusted to different pH values (3, 4, 5, 7 and 9) to concentrate CMP molecule in the retentate and separate other whey proteins through permeate. Feed pH of 9 and 7 provided an adequate flux with 9 kDa- and 25 kDa-membrane, respectively. A volumetric concentration factor of 4 was reached with both membranes by UF and subsequent DF, but the process time was shorter with 25 kDa-membrane because of the higher permeate flux. One DF cycle was possible with 25 kDa-membrane as there was a substantial loss of CMP compared to four DF cycles with 9 kDa-membrane. About 58% of CMP in whey was recovered using 9 kDa-membrane while 33% of it was recovered with 25 kDa-membrane by the whole process. α-Lactalbumin, β-lactoglobulin, tyrosine and phenylalanine contents in the final concentrate, which are related to the purity of CMP were found similar in both cases. Sweet whey pre-treatment was the key point for purity of CMP concentrate before UF/DF. Both PES membranes can be used for the production of a CMP concentrate depending on desired recovery, composition and process time.

This research aimed to analyse the influence of Apis mellifera intermissa honey supplementation on the technological, physicochemical, microbiological and sensory characteristics of stirred goat yoghurt containing Lactiplantibacillus plantarum C78, a novel probiotic strain, during 28 days of refrigerated storage. Four formulations of yoghurt were prepared, with different honey contents (0.5 %, 10 % and 15 %), and all samples were inoculated with the probiotic strain. The colour, syneresis (52.45 ± 0.19%), viscosity (28 ± 0.25 Pa.s) and sensory acceptance were improved in samples having 15% honey. The viability of L. plantarum C78 in all yoghurt samples presented counts above 7 log CFU/mL until the day-28 of refrigerated storage and honey increased the count of probiotic culture to 8.5 and 8.7 log CFU/mL at day-14 and day-21 of storage. These results reveal a successful incorporation of both probiotic and honey and promote the nutritional and sensory properties of the new yoghurt formulation.

The quality of colostrum is essential for the successful transfer of passive immunity and the early development of the immune system in newborns. This research was conducted with the aim of evaluating the agreement between measurements from different equipment: colostrometer, digital Brix refractometer and optical Brix refractometer, using fresh colostrum samples maintained at 21°C. Colostrum samples were collected from two farms (n₁ = 31 and n₂ = 193). Farm 1 included females from second to ninth lactation, comprising 15 Holstein Friesian (HF), 5 Jersey and 11 Holstein × Jersey crossbreeds. Farm 2 had HF heifers and cows from first to seventh lactation. Immunoglobulin content was assessed indirectly with a colostrometer and both types of Brix refractometers (digital and optical). For the correlation analysis, Pearson's product-moment method was used to assess the linear association between the equipment, followed by a Student's t-test and comparison of the obtained values with specific correlation coefficients (50%, 70%, 90% and 99%). There was a 98% correlation between the refractometers on Farm 1, which was significantly higher (P < 0.0001) than the commonly used reference values for weak (50%), moderate (70%) and strong (90%) correlations, and statistically equivalent to a 99% correlation. This indicates a very high, positive linear association between the digital and optical Brix refractometers. On Farm 2, a 97% correlation was found between the refractometers, which was significantly higher (P < 0.0001) than the specific reference values of 50%, 70% and 90%, but significantly lower than a 99% correlation.

This research paper describes the effect of fermented substrates comprised of dairy by-products and underutilised cereals on murine faecal enzymes and faecal microbial profiles, and the development of the fermented substrate into a sour-spicy beverage for human consumption. A fermented substrate was made by using dairy by-products and underutilised cereals, whey and skim milk blend (60:40, v/v), germinated pearl millet flour and barley malt extract. The substrate was fermented with Lactobacillus acidophilus NCDC 13. The growth pattern of the organism in the composite substrate was satisfactorily described by a logistic-type equation. Faecal samples were obtained from 18 Swiss albino male mice that had been fed on either a control diet (n = 6), a diet based on an unfermented substrate, and a diet based on a fermented substrate (six in each group) and analysed. The fermented substrate caused a significant (P < 0.05) increment in faecal lactobacilli with a concomitant reduction in faecal coliform counts. Further, the fermented substrate caused a significant (P < 0.05) and sustainable decline in faecal enzyme β-glucuronidase activity in the mouse model, which is commonly considered a marker of colon cancer. The reductions in the numbers of coliform bacteria in faeces might explain the decline in faecal enzyme activity. Beta-glucuronidase is an enzyme produced by faecal bacteria that converts procarcinogens to potential carcinogens from available substrates. Bifidobacteria and lactobacilli generally have lower activities of these harmful enzymes, whereas β-glucuronidase is produced in high amounts by enterobacteria and clostridia spp. The fermented substrate was developed into a sour and spicy beverage for human consumption. The average TS, fat, protein, ash, starch and fibre contents of the beverage were 11%, 0.3%, 2%, 0.61%, 1% and 1.4%, respectively. The sensory score with an overall acceptability of 7.5, revealed that the product was sensory acceptable.

Diagnosis of cases of Mycoplasma mastitis is particularly challenging due to their unique biological characteristics, which complicate diagnosis and treatment. Hence, accurate and quick diagnostic tests for early detection of Mycoplasma mastitis are essential to initiate appropriate interventions or culling. The objective of this research is to estimate the diagnostic performance of the molecular microarray assay (MMA) against bacterial culture for the diagnosis of bovine intramammary infections (IMI) with Mycoplasma spp., using a gold standard approach and the Kappa agreement coefficient. A total of 395 quarter milk samples were collected from cows in 31 dairy herds with conventional milking systems in California, USA. Following dairy personnel practices, milk samples were collected from the lactating cows showing abnormal milk characteristics and shipped within 24 hours to the laboratory for bacterial culture and MMA examination. Milk samples with positive growth were confirmed via PCR test to eliminate misdiagnosis of Acholeplasma spp. Eighty-seven cows (22%) were positive for Mycoplasma spp. IMI and the test accuracy was 88.4%. The sensitivity of MMA was 90.8% (95% CI (Confidence Interval): 82.68-95.95), and the specificity was 87.66% (95% CI: 83.46-91.12). The positive predictive value of MMA in these herds was 67.52% (95% CI: 60.51-73.83), and the negative predictive value was 97.12% (95% CI: 94.57-98.49). Calculated Kappa coefficient was 0.70 (95% CI: 0.618-0.778). The high estimates of sensitivity and specificity of MMA suggest its usefulness as a routine and quick test for accurate diagnosis of Mycoplasma spp. IMI in dairy cows. Our findings indicate that MMA holds promise for enhancing the detection of Mycoplasma spp. and could potentially revolutionize diagnostic practices in the dairy industry and supports udder health management.

To determine the long-term effects of transition milk (TRANS), 30 female Holstein calves were allocated to two feeding groups (n = 15/group) after colostrum intake, receiving either 12 L of TRANS of their dam or 12 L of milk replacer (MR) per day. After 5 d of differential feeding, all calves received 12 L of MR/d. Until calving, heifers were weighed monthly. After calving, BW was recorded twice daily after milking. Body condition (BCS) and back fat thickness (BFT) were scored biweekly. Milk yield was recorded twice daily until d 200 in milk. Milk composition (protein, fat, and lactose), as well as somatic cell count (SCC) were analysed biweekly. Blood samples were taken 3 weeks before calving, at the day of calving and 3 weeks thereafter. Oxidative status was assessed as ferric reducing ability of plasma (FRAP) for antioxidative capacity, and as reactive oxygen metabolites via the dROM assay. Oxidative damage of lipids was measured via the thiobarbituric acid-reactive substances (TBARS) assay; peroxidized proteins were assessed using the advanced oxidation protein products (AOPP) assay. Performance until first insemination did not differ between the groups, as well as BW development until the first weeks of lactation. From week 7 of lactation onwards, TRANS had less BW than MR heifers but tended to have a higher BCS. Milk yield and composition did not differ between both treatments. Marker for oxidative stress showed typical patterns of increasing antioxidants before calving and increase in prooxidants after calving in both treatment groups. The results indicate that feeding TRANS in the first 5 days of life had no long-term effects on performance in the first lactation, except for lower postpartum BW in heifers fed TRANS than MR, under the current rearing and management conditions.

This study investigated yeast diversity and physicochemical changes during the production of Kargı Tulum cheese, a traditional Turkish cheese. Samples were collected at six key stages, from raw milk to the final product, and analysed for parameters including pH, titratable acidity, dry matter, fat, salt, protein, water-soluble protein and maturation index. During ripening, pH values ranged from 3.03 ± 0.017 to 3.70 ± 0.017, while titratable acidity increased from 0.91% ± 0.16% to 3.33% ± 0.17%. Dry matter and fat content increased significantly, reaching 50.41% ± 1.56% and 33.50% ± 5.41%, respectively. Salt content ranged from 0.58% ± 0.08% to 3.03% ± 0.58%, and protein content from 3.70% ± 0.93% to 20.63% ± 1.16%. The maturation index increased from 5.54% ± 0.71% to 16.26% ± 4.35%, indicating ongoing proteolysis. A total of 42 yeast isolates were phenotypically characterized and grouped by sugar fermentation ability, growth and salt tolerance. Internal transcribed spacer region sequencing identified key yeast species, including Kazachstania unispora, Pichia fermentans, Kluyveromyces lactis, Pichia membranifaciens and Geotrichum candidum. These species play significant roles in cheese maturation, contributing to flavour and texture. The results emphasize the importance of indigenous yeast populations in traditional cheese production and offer insights for improving fermentation and ripening processes to enhance cheese quality.

The main challenge to producing a nutritionally improved milk fat composition is to increase monounsaturated fatty acids (MUFA) and decrease saturated fatty acids (SFA) without detriment to dairy product characteristics. Our aim was to determine the optimal amount of intestinally available oleic acid (via abomasal infusion) to produce higher-MUFA milk fat with satisfactory functional characteristics for ice cream. One control and four increasing doses of free fatty acids (FA) from high oleic sunflower oil (HOSFA) were infused into the abomasa of four lactating dairy cows in a changeover design with periods of 7 d. Treatments were (1) control (no FA infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Ice cream mixes were prepared with butter oil from all treatments. Samples prepared from control and 500 g/d HOSFA infusion were evaluated by a judging panel in a triangle test. Statistical analysis of results showed linear changes in most of the variables analysed as HOSFA infusion increased. For ice cream under freezing temperatures, the 500 g/d level was optimal. Sensory evaluation analysis indicated no statistical difference between ice creams prepared from the control and 500 g/d HOSFA infusion. Changes in 23 triacylglycerol fractions were statistically correlated to functional properties at 10 min of freezing. The decrease in fractions with SFA (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and the increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein were some of the most highly correlated with ice cream functional properties as the result of increasing HOSFA infusion. We were able to produce an ice cream with desirable physical and organoleptic qualities, yet containing twice as much oleic acid and two-thirds as much palmitate as a control ice cream.

This study evaluated the effect of sweet whey fermented by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772, an exopolysaccharide (EPS)-producing lactic acid bacterium (LAB), on the yield and quality of Requeson, a traditional Mexican fresh cheese, further supplemented with the probiotic strain Lactobacillus casei 431. Fermentation of the whey at 42°C for 48 hours resulted in the production of 1.126 ± 0.12 mg_eq dextran/mL of EPS. The incorporation of this EPS-rich whey led to a marked (∼230%) increase in cheese yield and significantly enhanced textural properties, including greater hardness, cohesiveness and elasticity. Furthermore, L. casei 431 maintained viability above 10⁷ cfu/g throughout 21 days of refrigerated storage (4°C), with no detectable microbial contamination. Although formulations containing EPS were slightly preferred in sensory evaluations, they exhibited improved stability and retained overall acceptable sensory quality. These results highlight the potential of EPS-producing LAB and probiotics to improve the technological, nutritional and functional attributes of fresh cheese, while contributing to the valorisation of dairy by-products.

Food wastes are thought to be a substantial source of bioactive components with many functions and varying biological activities, therefore, numerous studies have been conducted on the use of these wastes to maximize their benefits. Nano-materials have been demonstrated that have higher bioavailability, functionality and effectiveness in the food systems. This study was conducted to determine how the nutritional value and quality characteristics of ice cream would be affected by the use of nano-powders made from apricot (Prunus sp.) and peach (Prunus persica L. Batsch) kernels, watermelon (Citrullus lanatus) rind and banana (Musa spp.) peel as functional additives (1%).The tested nano-waste powders significantly (P < 0.05) increased the total solids, protein, fat and ash contents distinctly with apricot kernels (AK) and peach kernels (PK). The physiochemical properties of ice cream mix and the final product were also affected with a significant increase of viscosity and overrun. Watermelon rind (WMR) and banana peel (BP) boosted the total phenolic content and diphenyl-1-picrylhydrazyl (DPPH) scavenging activity (%) as compared to the control and other wastes. The added nano-waste powders, except for BP, enhanced the meltability, microstructure properties and improved the sensory attributes of the resultant ice cream during 30 days of storage compared to control. The study recommends utilization of the tested nano fruit wastes as value added components to create innovative and higher-quality ice cream.