瑞士乳杆菌对契达干酪成熟期间品质的影响

干酪的成熟是形成干酪特有的组织状态、质地和风味的关键工序。将分离自内蒙古传统乳制品中的瑞士乳杆菌SMN2-1作为非发酵性乳酸菌添加到契达干酪的生产中,通过检测其成熟过程中理化指标、气味变化和质构特性等指标,分析了瑞士乳杆菌对契达干酪成熟的影响。结果显示:在90 d的成熟期内,两组干酪的蛋白质、脂肪、水分和盐分含量之间差异不显著(p>0.05),但添加瑞士乳杆菌SMN2-1的干酪成熟第90 d的气味明显改变,内聚性、弹性和咀嚼性等物性指标均高于对照,因此添加瑞士乳杆菌SMN2-1可以有效促进蛋白质分解和干酪的成熟,同时改善干酪的风味和质地。     

Effect of microencapsulated ferrous sulfate particle size on Cheddar cheese composition and quality

Iron-fortified Cheddar cheese was manufactured with large microencapsulated ferrous sulfate (LMFS; 700–1,000 µm in diameter) or small microencapsulated ferrous sulfate (SMFS; 220–422 µm in diameter). Cheeses were aged 90 d. Compositional, chemical, and sensory characteristics were compared with control cheeses, which had no ferrous sulfate added. Compositional analysis included fat, protein, ash, moisture, as well as divalent cations iron, calcium, magnesium, and zinc. Thiobarbituric acid reactive species assay was conducted to determine lipid oxidation. A consumer panel consisting of 101 participants evaluated the cheeses for flavor, texture, appearance, and overall acceptability using a 9-point hedonic scale. Results showed 66.0% iron recovery for LMFS and 91.0% iron recovery for SMFS. Iron content was significantly increased from 0.030 mg of Fe/g in control cheeses to 0.134 mg of Fe/g of cheese for LMFS and 0.174 mg of Fe/g of cheese for SMFS. Fat, protein, ash, moisture, magnesium, zinc, and calcium contents were not significantly different when comparing iron-fortified cheeses with the control. Iron fortification did not increase lipid oxidation; however, iron fortification negatively affected Cheddar cheese sensory attributes, particularly the LMFS fortified cheese. Microencapsulation of ferrous sulfate failed to mask iron's distinct taste, color, and odor. Overall, SMFS showed better results compared with LMFS for iron retention and sensory evaluation in Cheddar cheese. Results of this study show that size of the microencapsulated particle is important in the retention of the iron in the cheese and its sensory attributes. This study provides new information on the importance of particle size with microencapsulated nutrients.     

低脂乳的不同热处理工艺对切达奶酪品质的影响

通过对切达奶酪p H、水分含量、产率、质构和融化性的测定,研究了低脂乳的不同热处理工艺对其品质的影响。结果表明:3个不同热处理工艺下乳清蛋白变性率分别为17.5%、35.1%和68.3%。随着热处理强度的增大,切达奶酪的p H和融化性下降,水分含量和产率提高,质构指标中的硬度、弹性、内聚性和咀嚼度下降,黏着性上升。利用扫描电镜和电泳技术分析不同热处理工艺对奶酪品质造成的差异。结果表明:随着热处理强度的增大,乳清蛋白变性率增大,形成的大分子聚合物被截留在奶酪的网状结构中,影响了酪蛋白的聚集,进而对其品质产成了影响。      

Low‐fat Cheddar cheese made using microparticulated whey proteins: Effect on yield and cheese quality

Influence of different levels (0, 0.15, 0.35 or 0.50%) of microparticulated whey protein (MWP) on yield and quality of low‐fat (~7.3 g/100 g) Cheddar cheese was investigated. MWP improved cheese yield due to the water‐binding ability of denatured whey protein. MWP addition decreased meltability but improved the textural properties beneficial for shredding and slicing, by decreasing sensory firmness. The results emphasise the role of MWP as an inert filler within cheese matrix, in improving cheese yield and creating a softer texture without compromising the sensory or overall quality of cheese, even with moisture increases in 0.35 or 0.50% MWP cheeses.     

Effect of incorporation of denatured whey protein on the yield and quality of Cheddar cheese

Concentrated suspensions of a denatured protein-fat complex were prepared by centrifugation of whey which had been heated in acid conditions. Significant improvements in cheese yield were obtained on adding the concentrate to milk for cheesemaking before renneting. A maximum increase in yield of 7% was attained in manufacturing Cheddar cheese which satisfied the legal requirements for moisture content. No consistent texture or flavour defects were evident in the cheese during the first jive months of maturation.     

The impact of reduced sodium chloride content on Cheddar cheese quality

The effect of varying salt (sodium chloride) addition levels of 0.50%, 1.25%, 1.80%, 2.25%, 2.50% and 3.00% (w/w) on the quality of Cheddar cheese was assessed. Reducing the salt adversely impacted Cheddar flavour and texture. The key compositional parameters of moisture-in-non-fat-substances and salt-in-moisture were most affected. Decreasing salt resulted in a concomitant reduction of pH, a slight reduction in buffering capacity and an increase in water activity and growth of starter and non-starter lactic acid bacteria that resulted in enhanced proteolysis. Lipolysis was not impacted by salt reduction. To produce quality reduced salt Cheddar cheese cognisance must be taken on how to reduce proteolysis, limit growth of NSLAB, reduce water activity, achieve pH 5.0–5.4 by modifications to the cheese making procedure to create a more appropriate environment for selected starter and/or adjunct cultures to generate acceptable Cheddar flavour and texture.     

Effect of sodium citrate on structure-function relationships of Cheddar cheese

The objective of this study was to determine the effect of sodium citrate on the structure and functionality of Cheddar cheese. The hypothesis was that citrate (sodium citrate) injection would affect cheese properties mainly through its effect on bound calcium (calculated as the difference between total calcium and the water-soluble calcium content of a cheese extract). A 9-kg block of Cheddar cheese was made, vacuum-packaged, and then stored for 2 wk at 4 degrees C. After storage, the cheese was cut into 0.5- to 0.6-kg blocks that were vacuum-packaged and stored for 1 wk at 4 degrees C prior to injection. Cheese blocks were then high-pressure injected with a buffer solution (pH 5.27) containing 40% (wt/ wt) citric acid trisodium dihydrate and 6.25% (wt/wt) anhydrous citric acid, from zero (control) to five times (successive injections performed 24 h apart). Increased citric acid content of cheese from 0.22 (uninjected) to 1.39% (after five injections) caused phosphate solubilization. Thus, the calculated bound phosphate content of cheese decreased from 0.54 to 0.45 mmol/g of protein. However, unexpectedly, the soluble calcium content decreased from 0.34 (control) to 0.28 mmol/g of protein (after five injections), whereas the bound calcium content remained unchanged (0.42 mmol/g of protein). The decrease in soluble calcium probably resulted from the formation and concentration of crystals in the cheese surface, which was not included in samples for analysis, and from the expulsion of serum from within the cheese. Higher concentration of solutes in the water phase of cheese would increase the volume of serum, but the cheese had limited holding capacity and serum was expelled. Citrate injection increased the sodium content of cheese from 0.63 to 0.93%, but it had no effect on cheese pH (5.2). After five injections, the protein matrix expanded, occupying an increased area of cheese matrix (83 vs. 78%). Even though citrate injection had no effect on bound calcium, and thus the rate and extent of cheese flow were unaffected, increased phosphate solubilization, and possibly decreased ionic calcium content, resulted in expansion of the protein matrix and increased cheese hardness.     

乳酸菌自溶对切达干酪成熟中蛋白质分解的影响

选取自溶度不同的乳杆菌作为附属发酵剂混合商业发酵剂制作切达干酪,研究了乳酸菌自溶对干酪成熟的影响.测定成熟期间各干酪中乳酸菌活菌数、pH值、pH4.6可溶氮质量分数和12%TCA可溶氮质量分数.并结合SDS-PAGE分析干酪蛋白质的水解情况.结果表明,各实验组干酪的12%TCA可溶性氮含量随着成熟时间延长逐渐增加.在1个月后不同组别之间差异显著(P<0.05).与对照组干酪相比,加入高自溶度菌株的实验组干酪蛋白分解程度较高,非蛋白氮的质量分数为8.00%.同时,SDS-PAGE结果显示,各干酪的蛋白质都有-定程度的分解.产物略有不同.乳酸菌自溶可以加速蛋白质分解.     

Microbiological quality of shredded Cheddar cheese packaged in modified atmospheres

The microbiological quality of shredded Cheddar cheese packaged in different modified atmospheres with and without oxygen scavengers included in the packaging film was studied with the aim of determining how modified air packaging would affect the mould species present on shredded Cheddar cheese. The film with oxygen scavengers was more effective than the control film against mould growth, whereas the 73% CO₂/27% N₂ atmosphere resulted in the cheese with the best microbiological qualities. The three modified atmospheres and the packaging film influenced the mycoflora of shredded Cheddar cheese as the mould species isolated initially differed, from those isolated at 16 weeks in the six treatments. This study demonstrated that O₂ scavengers were effective in controlling the growth of moulds on shredded Cheddar cheese.     

Effect of commercial lipolytic enzymes on flavour development in Cheddar cheese

The addition of commercial lipolytic enzymes to experimental Cheddar cheese accelerated the liberation of free fatty acids during ripening. The substrate specificity of the added enzymes generally governed the chain lengths of the free fatty acids in the cheeses. None of the enzymes accelerated the formation of typical flavour in either the presence or the absence of a flavour-enhancing proteinase, but higher addition levels produced lipolytic rancidity.     

Effect of various high-pressure treatments on the properties of reduced-fat Cheddar cheese

A major problem with reduced-fat cheese is the difficulty in attaining the characteristic flavor and texture of typical full-fat versions. Some previous studies have suggested that high hydrostatic pressure (HHP) can accelerate the ripening of full-fat cheeses. Our objective was to investigate the effect of HHP on reduced-fat (~7.3% fat) Cheddar cheese, with the goal of improving its flavor and texture. We used a central composite rotatable design with response surface methodology to study the effect of pressure and holding time on the rheological, physical, chemical, and microbial characteristics of reduced-fat Cheddar cheese. A 2-level factorial experimental design was chosen to study the effects of the independent variables (pressure and holding time). Pressures were varied from around 50 to 400 MPa and holding times ranged from 2.5 to 19.5 min. High pressure was applied 1 wk after cheese manufacture, and analyses were performed at 2 wk, and 1, 3, and 6 mo. The insoluble calcium content as a percentage of total Ca in cheeses were not affected by pressure treatment. Pressure applications ≥225 MPa resulted in softer cheese texture during ripening. Pressures ≥225 MPa increased melt, and resulted in higher maximum loss tangent values at 2 wk. Pressure treatment had a greater effect on cheese microbial and textural properties than holding time. High-pressure-treated cheeses also had higher pH values than the control. We did not observe any significant difference in rates of proteolysis between treatments. In conclusion, holding times of around 5 min and pressures of ≥225 MPa could potentially be used to improve the excessively firm texture of reduced-fat cheese.     

Consumer perception of smoked Cheddar cheese

Consumer perception of smoked cheese was evaluated through focus groups, surveys, and central location testing. Three focus groups (n = 29) were conducted with consumers of smoked cheese. Subsequently, 2 online surveys were conducted. The purpose of the first survey (n = 1,195) was to understand types of smoked cheeses consumed and if consumers associated specific wood smokes with smoked cheese. Next, an adaptive choice-based conjoint (n = 367) was designed to evaluate consumer perception of different attributes of smoked cheese. Maximum difference scaling and familiarity questions were also included in the adaptive choice-based conjoint survey. Following the surveys, a central location test (n = 135) was conducted with cheeses smoked with 3 different woods at a low and high intensity (6 cheeses total). Hierarchical Bayesian estimation, 1-way ANOVA, agglomerative hierarchical clustering, and 2-way ANOVA (smoke type × intensity level) were used to interpret the collected data. Results from the focus groups indicated that smoked cheese was perceived as an artisan, high-end product and that appearance and price were strong purchase factors. In general, consumers were not aware of how smoked flavor was imparted to cheese, but when informed of the processes, they preferred cold-smoked cheese to the addition of liquid smoke flavor. Results from both surveys confirmed focus group observations. Consumers perceived flavor differences among different wood smokes and smoked products. Method of smoking, smoke intensity, type of wood, and type of cheese were the most important attributes for purchase of smoked cheese. When tasting, consumers differentiated smoke aroma and flavor among cheeses and preferred cherry wood smoked cheeses over apple wood or hickory smoked cheeses. Understanding consumer perceptions of smoked cheese will give insight into the desired experience that consumers expect when purchasing smoked cheese.     

Cheddar干酪理化性质变化对其质构及微观结构的影响

在贮藏过程中干酪的理化变化对其质构起到重要作用,由于蛋白质的降解破坏了其网络结构,脂肪水解和氧化使脂肪球发生聚集融合,形成脂肪槽,这些变化促进了干酪质构的变化,使其质地变软.本文系统研究Cheddar干酪在贮藏期的蛋白质水解程度、脂肪水解和氧化程度、质构及微观结构的变化,分析蛋白质水解、脂肪水解对质构和微观结构的影响.     

切达干酪加速成熟方法及其研究现状

概述了对切达干酪的加速成熟的现状与研究方法,通过提高温度、添加促熟酶、修饰发酵剂细胞、高压处理等方法缩短切达干酪的成熟时间,提高经济效益。     

快速成熟契达干酪成熟期间的理化特性变化

对天然契达(Cheddar)干酪快速成熟期间理化特性进行了研究,结果表明,在21 d内,pH值呈下降趋势(P<0.05),在21 d到35 d的成熟中,pH值缓慢增加(P>0.05);Cheddar干酪快速成熟过程中由于蛋白酶和脂肪酶的作用使蛋白发生水解,pH值为4.6醋酸溶液—水溶性氮质量分数、质量分数为12%的三氯乙酸—可溶性氮和游离氨基酸(FAA)的质量分数都呈明显增加趋势(P<0.05);成熟过程中TPA各项指标均有不同程度的变化,硬度和凝聚性呈先下降后增加的趋势,弹性和咀嚼性呈先上升后下降的趋势。     

Effect of fortification with asparagus powder on the qualitative properties of processed cheese

The qualitative properties of processed cheese (PC) fortified with different levels of asparagus powder (AP) (0.5%, 1% and 1.5% wt/wt) were evaluated during storage. AP decreased the pH and lipolysis indexes and increased the phenolic content, antioxidant activity and proteolysis of the processed cheeses. AP made the structure of the cheese more elastic, increased the rigidity and decreased the spreadability compared with the control sample, which corresponded to the results obtained using dynamic oscillatory rheometry. The results showed that AP as a rich source of bioactive components could be used for the fortification of processed cheeses.     

Consumer perceptions of anticake agents on shredded Cheddar cheese

Prepackaged natural cheese shreds are a growing consumer category. Anticake agents are applied to commercial cheese shreds to assist with shelf life and ease of use. The objective of this study was to investigate consumer perception of 3 anticake agents applied at various levels to Cheddar cheese shreds. Three common anticake agents (80% potato starch/20% cellulose blend, 100% potato starch, or potato starch/corn starch/calcium sulfate blend) were applied to duplicate lots of Cheddar cheese shreds at 1, 2, 3, 4, and 5% (wt/wt). Control Cheddar cheese shreds with no anticake were also included. Sensory properties (appearance, flavor, texture, and hot texture) were documented using a trained sensory panel (n = 8), and 3 consumer acceptance tests were also conducted. In test 1, consumers (n = 110) visually evaluated liking of cold shred appearance. In test 2, consumers (n = 100) evaluated melted shreds on a flour tortilla for overall liking and appearance, flavor, and texture liking. In test 3, consumers (n = 49) participated in a home usage test. Two-way ANOVA (anticake × anticake application rate) was used to interpret the collected data from each test. Visual appearance of shreds was the primary attribute influenced by anticake application and anticake agent. Trained panel evaluation demonstrated that the 100% potato starch anticake had minimal effects on visual appearance. The other 2 agents (80% potato starch/20% cellulose blend and potato starch/corn starch/calcium sulfate blend) showed increases in visible powder at >3% (wt/wt). Consistent with results from trained panelists, higher application rates decreased consumer appearance and color liking for Cheddar shreds with 80% potato starch/20% cellulose and potato starch/corn starch/calcium sulfate blends at >2 or 3% (wt/wt), respectively. Appearance liking of melted shreds decreased with increased anticake application percent but decreased the most for 100% potato starch anticake at greater than 1% (wt/wt) application. Overall liking, flavor liking, and texture liking attributes for melted shreds were negatively affected at >3% (wt/wt) application regardless of anticake agent used. In general, anticake agents can be applied to Cheddar cheese shreds at up to 3% (wt/wt) with minimal effect on consumer perception.