Improvement in the quality of teleme cheese produced from ultrafiltered cow's milk

Mature teleme cheese produced from ultrafiltered milk has the disadvantage of a sandy texture as well as a small difference in its traditional taste due to the incorporation of whey protein. Batches of cow's milk, 300 kg each, were concentrated in an ultrafiltration unit. The addition of 0.5 per cent sodium chloride and ripening of the milk with a lactic starter so that the pH was reduced to 6.2 before beginning the ultrafiltration improved substantially the texture and the taste of the cheese. The yield of the experimental cheese is approximately 9 per cent higher than that of the control .     

Probiotic and antioxidant properties of C30 carotenoid-producing Lactiplantibacillus plantarum isolated from kimchi

Food Science and Biotechnology - This study focuses on the development of functional probiotics using caroteonid-producing lactic acid bacteria (LAB) with antioxidant properties. Thirty LAB strains...     

Manufacture of heat and acid coagulated cheese from ultrafiltered milk retentates

Ultrafiltration technology was used for the production of direct acidified cheese. Process parameters were optimized for cheese manufacture from whole milk retentates at 4:1 volume concentration ratio. Sensory evaluation indicated that cheese from ultrafiltration was preferred equally to traditional manufacture when the cheese was of similar composition, while citric acid was the preferred acidulent. An increase in cheese yield of 3.3% and an increase in yield on dry matter mass basis of 14.7% was achieved by use of ultrafiltration. Yield efficiencies based on protein, fat or total solids increased with retentate concentration.     

Sequential optimisation of yield and sensory quality of semi-hard cheese manufactured from a mixture of ultrafiltered ewes' and cows' milk

A Plackett-Burman (PB) experimental design was applied as a screening method to eight process factors. This method identified starter concentration and curd cutting size as the most significant parameters affecting the manufacture of semi-hard pressed cheese made from blended milk concentrated by ultrafiltration. Both factors, together with the bacterial starter composition, were subsequently evaluated at two levels in a full factorial design (FD). The PB and FD designs were optimised in accordance with yield and sensory quality. A partial least square calibration identified elasticity and internal and external visual evaluations as the main attributes that increased cheese quality. When the final optimised conditions were applied to the manufacturing process, milk diafiltration or pre-acidification and the cutting step were no longer necessary, making continuous cheesemaking process a simpler and more feasible alternative. The yield was 10% higher at the end of the optimisation with no negative effects on the sensory quality.     

牦牛、牛酸乳发酵过程中品质特性的变化规律

通过测定发酵过程中牦牛酸乳和牛酸乳的pH、酸度、质构、双乙酰和乙醛含量,分析两种酸乳在发酵过程中品质特性的变化规律。在整个发酵周期内,牦牛酸乳和牛酸乳的酸度呈上升趋势,pH则相应下降,两种酸乳之间无显著差异(p>0.05)。牦牛酸乳和牛酸乳在发酵0~3 h内质构特征几乎无变化,3~11 h内硬度、稠度、黏聚性和黏性指数显著上升(p<0.05),11 h之后各项指标变化不显著(p>0.05),且牦牛酸乳的质构指标均高于牛酸乳。两种酸乳的双乙酰和乙醛含量在前发酵期内显著上升(p<0.05),在后发酵期内出现一定波动但逐渐趋于稳定(7~11 mg/L),且牦牛酸乳与牛酸乳之间无明显差异。结论:在整个发酵周期(20 h)内,牦牛酸乳和酸乳的品质特性变化规律相同,除质构指标外其它测定指标无显著差异。     

Probiotic viability and physico-chemical and sensory properties of plain and stirred fruit yogurts made from goat's milk

Probiotic plain and stirred fruit yogurts were made from goat's milk using bacterial cultures comprising, Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12 and Propionibacterium jensenii 702. The products were stored at 4°C for 4weeks, during which time the viability of the yogurt starter culture and probiotic bacteria was analysed weekly. P. jensenii 702 demonstrated the highest viability (10(8)cfu/g) in all types of yogurt throughout the storage period, while the viability of the bifidobacteria (～10(7)cfu/g) also remained above the minimum therapeutic level. The viability of L. acidophilus LA-5 fell below 10(6)cfu/g in yogurts, however, the addition of fruit juice appeared to support the viability of lactobacilli, with higher microorganism numbers observed in fruit yogurts than in plain yogurt throughout the shelf life. Addition of fruit juice significantly increased the syneresis, and decreased viscosity and water holding capacity of yogurts (p<0.05), and also enhanced their sensory acceptability.     

Altering renneting pH changes microstructure, cell distribution, and lysis of Lactococcus lactis AM2 in cheese made from ultrafiltered milk

The objective of this study was to investigate the lysis of a highly autolytic strain of Lactococcus lactis ssp. cremoris AM2 in a model cheese made from concentrated ultrafiltered milk. From the same initial ultrafiltered retentate inoculated with L. lactis AM2, 5 cheeses were made by the addition of rennet at different pH values (6.6, 6.2, 5.8, 5.4, and 5.2). Lysis was monitored by measurement of the release of lactate dehydrogenase, an intracellular marker enzyme, and by immunodetection of intracellular proteins with species-specific antibodies. Confocal scanning laser microscopy (CSLM) was used to investigate the cheese microstructure by staining for protein and fat. Dual staining with a bacterial viability kit with CSLM was performed to reveal the integrity and localization of the bacterial cells. Levels of soluble calcium significantly increased when the pH at which the rennet was added decreased. In cheese renneted at pH 6.6, CSLM revealed an open porous structure containing a dense protein network with fat globules of different sizes distributed in the aqueous phase. In cheese renneted at pH 5.2, the protein network was homogeneous, with a less dense protein network, and an even distribution of fat globules. On d 1, bacterial cells were organized into colonies in cheese renneted at pH 6.6, whereas in cheeses renneted at pH 5.2, bacteria were evenly dispersed as single cells throughout the protein network. Lysis was detected on d 1 in cheeses renneted at high pH values and continued to increase throughout ripening, whereas induction of lysis was delayed in cheeses renneted at lower pH values until the end of ripening. This study demonstrates that alterations in the microstructure of the cheese and the distribution of cells play a role in lysis induction of L. lactis AM2.     

Probiotic fermented milk with high content of polyphenols: Study of viability and bioaccessibility after simulated digestion

This research evaluated the functional potential of a fermented milk made with Streptococcus thermophilus, a probiotic (Bifidobacterium animalis subsp. lactis) and pomegranate juice. Ferric‐reducing antioxidant potential, Trolox equivalent antioxidant capacity, scavenging effect on 1,1‐diphenyl‐2‐picrylhydrazyl free radical, oxygen radical absorbance capacity and Folin–Ciocalteu assays were used to estimate antioxidant activity and phenolic content. Probiotic survival, release and absorption of polyphenols were evaluated using in vitro gastrointestinal digestion. The concentration of polyphenols increased during digestion from 608 mg to 1417  gallic acid equivalents (GAE) /L. About 14% of polyphenols were found on the dialysate portion. The beverage presented high viability of probiotics with high survival rate after digestion (above 7 log cfu/mL).     

A comparison of the quality of Cheddar cheese produced from seasonal and standardized milk

The quality of Cheddar cheese made from seasonal and standardized milk has been assessed over a 12-month period. There was a slight consumer preference for cheese made from seasonal milk, but the difference was small and unlikely to be of commercial significance. Grade scores for cheese 'body' were not reflected in a consumer taste panel assessment of the quality of the mature cheese.     

Assessment of the quality of cottage cheese produced from standard and protein-fortified skim milk

The effects of milk protein fortification on the texture and microstructure of cottage cheese curd were evaluated. Protein powder (92.6% protein) was added to the skim milk at a level of 0.4% (w/w) to produce curds. Control curds with no protein powder addition were also produced. These curds were analysed for differences in yield, total solids, curd size, texture and structure. It was found that the addition of protein powder contributed to a significant yield increase, which can be attributed to increased water retention, with better curd size distribution. Control curds were firmer than the fortified curds and the structure showed less open-pore structure as revealed by electron microscopy. However, the addition of dressing masked the textural differences, and a sensory panel was unable to distinguish between cheeses produced from fortified milk and controls.     

酶制剂对Mozzarella水牛奶酪品质影响

比较了小牛皱胃酶、风味酶及菠萝蛋白酶对Mozzarella(莫兹瑞拉)水牛奶干酪的加工性状、质构及感官品质的影响.结果显示,用0.025 g/L风味酶添加到水牛奶中所制备干酪的产率、凝乳时间、凝乳性状、质构特征、感官品质均与小牛皱胃酶制备干酪的性状接近,说明风味酶可替代小牛皱胃酶用于Mozzarella水牛奶干酪的加工.     

Sensory properties of cheddar type cheese produced from recombined milk fat and casein fractions of bovine and ovine origin

The sensory properties of cheddar cheese produced from ovine and bovine milk and recombined mixtures of the fat and casein from the two species have been monitored at intervals over a nine month maturation period. Seven aroma, eleven flavour and five texture attributes were evaluated by an experienced sensory panel. To facilitate interpretation of sensory data, Factor Rotation was applied to the scores obtained by Principal Component Analysis. The sensory space maps resulting from this analysis clearly indicated that cheddar aroma and flavour originate predominantly in the protein fraction of bovine milk. The protein fraction is also dominant in the development of texture. Cheese produced from ovine protein is crumbly throughout maturation, whereas that produced from bovine protein becomes more crumbly with age.     

Effects of probiotic L. plantarum 299v on consumer quality,accumulation of phenolics,antioxidant capacity and biochemical changes in legume sprouts

This study evaluated the influence of Lactobacillus plantarum 299v on the consumer quality of legume sprouts. The probiotic-rich sprouts were produced by soaking the seeds in probiotic water suspension and further sprouting at 25 °C for 4 days. The enrichment of the sprouts with L. plantarum 299v only slightly affected the sensory quality - the overall acceptability of the probiotic-rich sprouts was usually higher. The probiotic-rich sprouts exhibited increased activity of polyphenol oxidase (the highest activity in the mung bean preparations - 73.97 U mg⁻¹ of protein). The peroxidase activity was not altered. The probiotic enrichment increased the phenolic content by 25%, 31% and 23% in the soybean, adzuki and mung bean preparations; however, it was not reflected in the antioxidant activities. The changes in the activity of enzymes involved in mobilisation of stored material (starch and proteins) and the increased content of phenolics only slightly modified the bioavailability of nutrients.     

Free fatty acids and quality of Domiati cheese made from dried milks as affected by added lipase

Domiati cheese was made from skimmed or whole dried milk with and without an added lipase preparation (Italase).Dried milk cheeses differed from fresh milk cheese in showing less flavour intensity and lower levels of free fatty acids with chain lengths of C₂ to C₁₈. Treatment of reconstituted milk with Italase, at a level of 0·02%, enhanced the formation of free fatty acids and this was associated with an improvement in cheese flavour. Thus the levels of free fatty acids and flavour intensities of dried milk cheeses with added lipase approached or even exceeded those of fresh milk cheese of the same pickling period.     

H HRMAS-NMR metabolomic to assess quality and traceability of mozzarella cheese from Campania buffalo milk

The production of Mozzarella di Bufala Campana (MBC) is relevant for the agro-food economy of the Campania Region of Italy and the mark of Protected Designation of Origin (PDO) has been assigned to MBC in relation to its geographical origin. Advanced analytical methods must be then employed to assess authenticity, traceability, and quality of MBC. ¹H HRMAS-NMR (High Resolution Magic Angle Spinning Nuclear Magnetic Resonance) spectroscopy was applied here to directly identify specific metabolites in MBC intact samples without time-consuming sample pre-treatments. Overcrowded conventional ¹H HRMAS-NMR spectra were selectively simplified with two NMR pulse sequences: eCPMG and eDiff, by modulating spin-spin relaxation times and diffusion of MBC molecular components, respectively. Signal elaboration of edited spectra was combined with multivariate analyses to enable significant metabolic differentiation between MBC samples from two different production sites in Campania. Principal Components Analysis (PCA) for eCPMG spectra explained 97.54% of total variance between the two MBC groups for four metabolites (β-galactose, β-lactose, acetic acid, and glycerol). Less efficient was groups distinction by PCA for eDiff spectra, although differences in polyunsaturated acids, such as linoleic and linolenic acids, were highlighted. Similarly, Discriminant Analysis (DA) provided MBC group classification with 100% success in validation tests for eCPMG spectra, while DA prediction ability was reduced to 94.12% for eDiff spectra. Hierarchical Cluster Analysis (HCA) gave a totally correct classification between the two MBC groups only for eCPMG spectra. eCPMG spectra were also used to identify metabolites during MBC aging. As compared to fresh samples, 2 days old MBC samples showed increasing signals for isobutylic alcohol, lactic acid, and acetic acid. This work shows that ¹H HRMAS-NMR spectroscopy can rapidly characterise the metabolic profile of intact MBC samples and statistically distinguish the geographical origin of buffalo milk mozzarella and its freshness.     

Degree of antioxidant protection: a parameter to trace the origin and quality of goat's milk and cheese

Traceability is an essential tool in reassuring consumers and traders that food is as safe, authentic, and of good quality as expected. Today, food traceability procedures often consist of attached documents and declarations, but scientific parameters that could objectively identify a product would be preferable. Scientific efforts in this area are mostly focused on selection and validation of experimental indicators that would be useful for tracing a food product in any step of its commercial life, describing its raw materials, processing procedures, and storage conditions. In this research, milk and cheese samples from zero grazing and grazing goats were studied to identify a tracing parameter correlated to the feeding system. In particular, α-tocopherol and cholesterol were analyzed by HPLC on a normal phase column and were combined to calculate the degree of antioxidant protection (DAP). This parameter, expressed as the molar ratio between antioxidant compounds and an oxidation target, is useful for tracing and distinguishing products from grazing and zero-grazing animals. Degree of antioxidant protection values greater than 7.0 × 10⁻³ were found in samples from grazing goats and values lower than 7.0 × 10⁻³ were found in samples from zero-grazing goats, for both milk and cheese, meaning that cholesterol was highly protected against oxidative reactions when herbage was the only feed or was dominant in the goat diet. The reliability of DAP to measure the antioxidant protection of cholesterol appeared more effective when the feeding system was based on grazing than when cut herbage was utilized indoors by animals. The DAP index was able to distinguish dairy products when the grazed herbage in the goats’ diet exceeded 15%.     

Standardization of milk using cold ultrafiltration retentates for the manufacture of Swiss cheese: effect of altering coagulation conditions on yield and cheese quality

Fortification of cheesemilk with membrane retentates is often practiced by cheesemakers to increase yield. However, the higher casein (CN) content can alter coagulation characteristics, which may affect cheese yield and quality. The objective of this study was to evaluate the effect of using ultrafiltration (UF) retentates that were processed at low temperatures on the properties of Swiss cheese. Because of the faster clotting observed with fortified milks, we also investigated the effects of altering the coagulation conditions by reducing the renneting temperature (from 32.2 to 28.3°C) and allowing a longer renneting time before cutting (i.e., giving an extra 5 min). Milks with elevated total solids (TS; ∼13.4%) were made by blending whole milk retentates (26.5% TS, 7.7% CN, 11.5% fat) obtained by cold (<7°C) UF with part skim milk (11.4% TS, 2.5% CN, 2.6% fat) to obtain milk with CN:fat ratio of approximately 0.87. Control cheeses were made from part-skim milk (11.5% TS, 2.5% CN, 2.8% fat). Three types of UF fortified cheeses were manufactured by altering the renneting temperature and renneting time: high renneting temperature = 32.2°C (UFHT), low renneting temperature = 28.3°C (UFLT), and a low renneting temperature (28.3°C) plus longer cutting time (+5 min compared to UFLT; UFLTL). Cutting times, as selected by a Wisconsin licensed cheesemaker, were approximately 21, 31, 35, and 32 min for UFHT, UFLT, UFLTL, and control milks, respectively. Storage moduli of gels at cutting were lower for the UFHT and UFLT samples compared with UFLTL or control. Yield stress values of gels from the UF-fortified milks were higher than those of control milks, and decreasing the renneting temperature reduced the yield stress values. Increasing the cutting time for the gels made from the UF-fortified milks resulted in an increase in yield stress values. Yield strain values were significantly lower in gels made from control or UFLTL milks compared with gels made from UFHT or UFLT milks. Cheese composition did not differ except for fat content, which was lower in the control compared with the UF-fortified cheeses. No residual lactose or galactose remained in the cheeses after 2 mo of ripening. Fat recoveries were similar in control, UFHT, and UFLTL but lower in UFLT cheeses. Significantly higher N recoveries were obtained in the UF-fortified cheeses compared with control cheese. Because of higher fat and CN contents, cheese yield was significantly higher in UF-fortified cheeses (∼11.0 to 11.2%) compared with control cheese (∼8.5%). A significant reduction was observed in volume of whey produced from cheese made from UF-fortified milk and in these wheys, the protein was a higher proportion of the solids. During ripening, the pH values and 12% trichloroacetic acid-soluble N levels were similar for all cheeses. No differences were observed in the sensory properties of the cheeses. The use of UF retentates improved cheese yield with no significant effect on ripening or sensory quality. The faster coagulation and gel firming can be decreased by altering the renneting conditions.