Influence of Homofermentative Lactobacilli on the Microflora and Soluble Nitrogen Components in Cheddar Cheese

Cheddar cheese was manufactured by inoculation with and without cultures of homofermentative Lactobacillus strains (L. casei-subsp-casei, L. casei-subsp-pseudoptantarum, L. plantarum). Growth rate of microflora, the incidence of heterofermentative lactobacilli and the rate of proteolysis were then studied during aging. The total number of psychotrophs, mesophiles and lactic streptococci reached a maximum at 5 months but maximum numbers attained were dependent upon the curing temperature (7°C or 15°C). The acceleration of cheese ripening by Lactobacillus cultures was accompanied by a greater degree of protein hydrolysis which was detectable after 8 months aging as soluble nitrogen in TCA extracts (360 mg/100g at 15°C and 240 mg at 7°C, versus 170 mg and 75 mg, respectively, for the controls).     

Impact of Autolytic and Proteolytic Lactobacilli and Nisin-Producing Culture on Proteolysis and Sensory Characteristics in Cheddar Cheese

ABSTRACT: Cheddar cheeses were made using a nisin-tolerant starter culture with either Lactobacillus delbrueckii subsp. bulgaricus UL12 (autolytic strain), Lactobacillus casei subsp. casei L2A (proteolytic strain), Lactococcus lactis subsp. lactis biovar. diacetylactis UL719 (nisin producer), or of Lb. bulgaricus UL12 and Lc. diacetylactis UL719. Lb. bulgaricus UL12 produced more trichloroacetic acid-soluble nitrogen than did Lb. casei L2A, which produced more phosphotungstic acid-soluble nitrogen than did Lc. diacetylactis UL719. High-performance liquid chromatography analyses showed that either lactobacilli or Lc. diacetylactis UL719 increased the hydrophilic and hydrophobic peptide contents. Cheeses containing both Lb. bulgaricus UL12 and Lc. diacetylactis UL719 had the most intense old Cheddar cheese flavor after 6 mo of ripening.     

Quality Attributes of Cheddar Cheese Containing Added Lactobacilli

Various strains of homo- and heterofermentative lactobacilli isolated from cheddar cheese were added to milk with a commercial streptococci culture to produce cheddar cheese. The heterofermatative lactobacilli L. brevis and L. fermentum almost always led to the development of fruity flavors, openness and late-gassing within 10 months of aging. Cheddar cheese produced using combined cultures of heterofermentative lactobacilli and L. casei-casei or L. casei-pseudoplantarum did not exhibit gas formation and openness. The overall grading scores of cheese containing added lactobacilli were not higher than those for the control cheese (without lactobacilli). A definite correlation was found between the lactobacilli used and the flavors of the cheese. The controlled acidity development during cheese making, the fat and the salt in moisture content of the cheeses were not affected.     

Heat-Shocked Lactobacilli for Acceleration of Cheddar Cheese Ripening

The aim of this study was to establish adequate conditions for heat-shocking cells of lactobacilli, to sufficiently suppress lactic acid production without damaging the proteolytic enzyme system important for cheese maturation. Three temperatures, 65, 67 and 70°C were tested, for 22 sec. The best combination for maximum retardation of lactic acid production and minimum damage to the proteolytic system was obtained by treating cells at 67°C for 22 sec. Following such treatment, lactic acid production was retarded by 24 hr, while the proteolytic enzyme system remained scarcely unchanged.     

Probiotic Cheddar Cheese: Influence of Ripening Temperatures on Proteolysis and Sensory Characteristics of Cheddar Cheeses

ABSTRACT:  Bifidobacterium longum 1941, B. animalis subsp. lactis LAFTI^® B94, Lactobacillus casei 279, Lb. casei LAFTI L26, Lb. acidophilus 4962, or Lb. acidophilus LAFTI L10 were used as an adjunct in the production of Cheddar cheeses, which were ripened at 4 and 8 °C for 24 wk. Effects of ripening temperatures and probiotic adjuncts on proteolysis and sensory evaluation of the cheeses were examined. Higher ripening temperature increased the level of proteolysis in the cheeses. Product of proteolysis and organic acids released during ripening were shown to be important for the flavor of Cheddar cheeses. There were positive and significant correlations between the levels of soluble nitrogen, lactic, acetic, and butyric acids, percentage hydrolysis of α_s1-CN and β-CN to the scores of cheddary flavor ( P < 0.05). Scores for sour-acid and vinegary flavors were higher in cheeses with the addition of Bifidobacterium sp. or Lb. casei 279 ripened at 8 °C. The scores were positively and significantly correlated to the level of lactic, acetic, and free amino acids in the cheeses ( P < 0.05). The results show that both 4 and 8 °C have potential for use in the ripening of probiotic Cheddar cheeses.     

Accelerated Maturation of Cheddar Cheese: Influence of Added Lactobacilli and Commercial Protease on Composition and Texture

The addition of live and heat-shocked Lactobacillus casei-casei L2A and Neutrase© was tested for its ability to accelerate the maturation of Cheddar cheese. An evaluation of physicochemical and rheological properties showed that cheese pH was decreased by bacterial and enzymatic additives, while fracturability and cohesiveness were influenced principally by Neutrase. The integrated process recommended is composed of three parts: first, the addition of live L. casei-casei L2A to control the undesirable microflora, second, heat-shocked cells of the same species at a concentration of 1.0%, and third, Neutrase at a concentration not higher than 1.0 × 10^-5 AU/g of cheese. This process led to a good-quality sharp Cheddar cheese with 60% increase in flavor intensity compared to control cheese.     

藏灵菇胞外多糖的理化性质及其在切达干酪中的应用

藏灵菇KW1在SDM培养基、37 ℃条件下发酵产胞外多糖（exopolysaccharide,EPS）达624.82?mg/L,经分离纯化及单糖分析测定,明确此多糖由鼠李糖、阿拉伯糖、甘露糖、葡萄糖和半乳糖组成,相对物质的量比1∶3.02∶2.12∶1.59∶3.04。红外光谱结果显示该EPS表现出典型的多糖吸收峰模式;扫描电镜显示,藏灵菇KW1?EPS微观结构中分布着许多球形结构和片状结构,且表面比较光滑;原子力显微观察表明,EPS具有一定聚集现象,呈现出膜状、簇状结构。将藏灵菇KW1?EPS应用于发酵剂菌株培养以及切达干酪制作中,结果表明EPS对发酵剂菌株生长有促进作用,并且随着添加量的增加,这种作用先增强后减弱。同时EPS的加入能提高干酪得率、持水能力以及成熟期间的活菌数。采用气相色谱-质谱联用从干酪中检测出69?种挥发性物质,香气活性值显示共有17?种风味物质对EPS干酪整体风味有贡献,其中丁酸乙酯、己酸乙酯、辛酸乙酯是关键性风味物质。本研究可为藏灵菇EPS在发酵乳制品中的应用提供一定技术参考。     

Effect of Added Lactobacilli on Composition and Texture of Cheddar Cheese During Accelerated Maturation

The evolution of cheese composition and texture was studied in maturing Cheddar cheese supplemented with live cells and cell homogenates of Lactobacillus casei-casei L2A in order to accelerate maturation. The pH was significantly modified by the lactic acid of the bacterial additives. The Theological properties showed the same general pattern of evolution in experimental as in control cheeses. The process we developed has led to a good-quality matured cheese with 40% increase in flavor intensity compared to control cheeses.     

Flavor of Cheddar Cheese: A Chemical and Sensory Perspective

Considerable knowledge has been accumulated on the biochemical processes occurring during ripening of Cheddar cheese, which in turn has major consequences on flavor and texture development. The present review outlines major metabolic pathways and agents involved in the modification of milk constituents in Cheddar cheese ripening. Mechanisms of volatile flavor and off‐flavor production and recent developments in the analysis, both sensory and instrumental, of Cheddar flavor and flavor compounds are also detailed here.     

Reduction of Sodium Chloride in Cheddar Cheese: Effect on Sensory,Microbiological, and Chemical Properties

AbsractCheddar cheese containing selected levels of added NaCl ranging from 0 to 1.44% was evaluated for various chemical, microbiological, and sensory properties over a 7-mo ripening period. Cheese with the least NaCl showed an increase in proteolysis and water activity. Cheese with less salt supported higher lactic acid bacteria populations. Trained panel evaluation of the experimental cheese with reduced levels of NaCl showed an increase in adhesiveness, cohesiveness, acidity, bitterness, unpleasant aftertaste, and a concomitant decrease in firmness and saltiness. Consumers were unable to detect flavor and texture differences in cheese containing 1.44 and 1.12% NaCl. Although consumers noted a difference between 1.12 and .73% NaCl, cheese with .73% salt received acceptable overall desirability ratings.     

Effect of Lactobacilli on the Properties of Swiss Cheese

Two Lactobacillus strains produced by mutagenesis of Lactobacillus bulgaricus AR2 were selected on the basis of the flavor generated after their growth in milk or whey permeate, and these strains were tested for acid development and proteolysis in milk cultures. Although differences in the flavor generated by the mutants and their parent strain could not be verified by a formal panel, there were significant differences between the mutants and their parent strain in proteolysis and acid development. Strain AR2, its two mutants, and two other lactobacilli that differed from them in flavor, proteolysis, and acid development were used to make Swiss cheese on a small scale. Significant differences were found in the flavor, proteolysis, and texture of the cheeses made with different strains of lactobacilli.     

High Pressure Treatment of Milk and Effects on Microbiological and Sensory Quality of Cheddar Cheese

The effect of cycled high pressure treatment of milk on the yield, sensory, and microbiological quality of Cheddar cheese was investigated. Cheddar cheeses were made from pasteurized, raw, or pressure treated milk according to traditional methods. Flavor scores from trained dairy judges were not different for pasteurized and pressurized milk cheeses (P≤0.05). Percent moisture and wet weight yields of pressure treated milk cheeses were higher than pasteurized or raw milk cheeses (P≤0.05). Microbiological quality of pressurized milk cheeses was comparable to pasteurized milk cheeses. Texture defects were present in pressurized milk cheeses and were attributed to excess moisture. High pressure treatment of milk shows promise as an alternative to heat pasteurization prior to cheesemaking.     

Relation between Melting and Textural Properties of Process Cheddar Cheese

Meltability and textural characteristics were evaluated in 48 batches of process Cheddar cheese prepared in pilot plant equipment. Correlation between melting spread at 139°C and cohesiveness at 21°C was positive and large. Prolongation of cooking up to 15 min at 74°C lowered meltability and cohesiveness. Within the range of weighted average ages of cheese (3 to 5.8 mo), no relation between melting spread or cohesiveness and age was consistent.     

Evolution of Free Amino Acids during the Ripening of Cheddar Cheese Containing Added Lactobacilli Strains

Cheddar cheese was produced with different lactobacilli strains added to accelerate ripening. The concentration of proteolytic products was determined as free amino acids in the water-soluble fraction at two, four, seven and nine months of aging and at two different maturation temperatures (6°C, 15°C). All amino acids increased during ripening and were higher in the Lactobacillus- added cheeses than in the control cheese, and higher in cheeses ripened at 15°C than at 6°C. Glutamic acid, leucine, phenylalanine, valine and lysine were generally in higher proportion in all cheeses. The cheeses with added L. casei-casei L2A were classified as having a “strong Cheddar cheese” flavor after only seven months of ripening at 6°C.     

氯化钠添加量对Cheddar干酪品质和介电特性的影响

以不同氯化钠(NaCl)添加量(0%、1%、2%、3%)的切达干酪(Cheddar cheese)为材料,对其90 d成熟期内的理化指标和成熟变化进行质构特性分析和介电特性测试,研究NaCl添加量对切达干酪成熟发育的影响。结果表明,NaCl添加量对干酪的理化指标有显著影响。NaCl添加量增加,干酪水分含量和水分活度下降、脂肪含量增加,并具有显著的相关性。低添加量NaCl对干酪成熟度的促进作用明显高于高添加量,NaCl添加量为1%、2%对干酪蛋白水解为指标的成熟度有显著加速作用;高NaCl添加量(3%)对干酪成熟过程的蛋白质水解有显著的抑制作用;切达干酪相对介电常数与NaCl的添加量无显著的相关性,而干酪介电损耗因子随NaCl添加量的增加而上升。并且,NaCl添加量对切达干酪成熟期内的硬度、咀嚼性有显著影响。     

Milk Plasmin Activity Influence on Cheddar Cheese Quality during Ripening

Up to six-fold increase in plasmin activity in milk did not significantly (p<0.05) affect the composition (moisture, protein, NaCl) of cheese, although a slight increase in moisture and decrease in protein content of the cheese was noted. Proteolysis in cheese increased with plasmin activity, resulting in improved flavor and overall quality of the cheese after 3 and 6 months ripening. Consistently, increasing the plasmin activity in milk about three-fold resulted in cheese of superior sensory quality.     

不同发酵剂对切达干酪成熟期间品质的影响

应用乳酸乳球菌乳酸亚种LA、乳酸乳球菌乳脂亚种LC以及不同比例混合菌(LA∶LC=1∶1,LA∶LC=1∶2,LA∶LC=2∶1)制作切达干酪,研究这5种发酵剂在干酪成熟过程中对其质构、感官、风味物质形成及蛋白水解程度等方面的影响。结果表明:3种不同比例组合菌株发酵剂的蛋白水解能力适中,生产出的干酪口味清淡,其中按1∶1接种制作的干酪具有良好的成熟度、质地和风味,具有一定的商业应用价值,可将其用于切达干酪的生产。