Cheddar cheese taste can be reconstructed in solution using basic tastes

The taste of cheese contributes to flavour character directly and by cross-modal interactions with aroma. However, the relative contribution of specific tastes, i.e., sweet, salt, umami, sour, and bitter, is not well understood. Twelve cheeses were profiled by a trained sensory panel and the five tastes shown to significantly differ in intensity. Sucrose, NaCl, monosodium glutamate, lactic acid, and caffeine were mixed in water and adjusted using a 2^5-1 fractional factorial design (FFD) to reconstruct cheese taste; the optimised construct was compared with a Cheddar cheese to measure similarity for each taste type. The FFD provided knowledge of taste–taste interactions and aided the reconstruction of the taste profile of Cheddar cheese in solution. The reconstructed cheese solution did not significantly differ in overall intensity, saltiness, sourness, umami, and bitterness from the Cheddar cheese based on chi-squared tests. Sweetness was a difficult attribute to adjust due to its relatively low intensity.     

Monitoring the ripening process of Cheddar cheese based on hydrophilic component profiling using gas chromatography-mass spectrometry

We proposed an application methodology that combines metabolic profiling with multiple appropriate multivariate analyses and verified it on the industrial scale of the ripening process of Cheddar cheese to make practical use of hydrophilic low-molecular-weight compound profiling using gas chromatography-mass spectrometry to design optimal conditions and quality monitoring of the cheese ripening process. Principal components analysis provided an overview of the effect of sodium chloride content and kind of lactic acid bacteria starter on the metabolic profile in the ripening process of Cheddar cheese and orthogonal partial least squares-discriminant analysis unveiled the difference in characteristic metabolites. When the sodium chloride contents were different (1.6 and 0.2%) but the same lactic acid bacteria starter was used, the 2 cheeses were classified by orthogonal partial least squares-discriminant analysis from their metabolic profiles, but were not given perfect discrimination. Not much difference existed in the metabolic profile between the 2 cheeses. Compounds including lactose, galactose, lactic acid, 4-aminobutyric acid, and phosphate were identified as contents that differed between the 2 cheeses. On the other hand, in the case of the same salt content of 1.6%, but different kinds of lactic acid bacteria starter, an excellent distinctive discrimination model was obtained, which showed that the difference of lactic acid bacteria starter caused an obvious difference in metabolic profiles. Compounds including lactic acid, lactose, urea, 4-aminobutyric acid, galactose, phosphate, proline, isoleucine, glycine, alanine, lysine, leucine, valine, and pyroglutamic acid were identified as contents that differed between the 2 cheeses. Then, a good sensory prediction model for “rich flavor,” which was defined as “thick and rich, including umami taste and soy sauce-like flavor,” was constructed based on the metabolic profile during ripening using partial least squares regression analysis. The amino acids proline, leucine, valine, isoleucine, pyroglutamic acid, alanine, glutamic acid, glycine, lysine, tyrosine, serine, phenylalanine, methionine, aspartic acid, and ornithine were extracted as ripening process markers. The present study is not limited to Cheddar cheese and can be applied to various maturation-type natural cheeses. This study provides the technical platform for designing optimal conditions and quality monitoring of the cheese ripening process.     

A Comparison of Available Methods for Determining Salt Levels in Cheese

Comparative salt analyses were run on seven different types of cheese using each of four methods: Mohr, Volhard, ion selective electrode, and chloride analyzer. The results of Volhard, Mohr, and chloride analyzer methods were similar for unaged cheese varieties, i.e., Mozzarella, Cheddar, Ricotta, Romano, and Provolone, but concentrations detected with the ion selective electrode were lower than the other three methods. Results were similar with aged Cheddar and process cheeses except the Mohr procedure proved unreliable. A constant correction factor could be used to make the ion selective electrode results similar to that obtained with the Volhard procedure.     

Assessment of Cheddar Cheese Quality by Chromatographic Analysis of Free Amino Acids and Biogenic Amines

The free amino acids and biogenic amines extracted from normal and late-gassing Cheddar cheeses were derivatized with heptafluorobutyric anhydride and trifluoroacetic anhydride, respectively, before quantification by gas-liquid chromatography. On a microgram scale, twenty amino acids were positively identified in both types of cheese, but only high levels of γ-amino acid butyrate (0.3 to 19.4 mg/g) and small quantities of arginate were found to be associated with “poorly aged” Cheddar cheeses. Histamine (1.54 and 1.22 mg/g) and tyramine (0.32 and 0.43 mg/g) were the bioamines present in highest concentrations in both cheeses.     

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.     

Effects of Gamma Irradiation at -78°C on Microbial Populations in Dairy Products

The effect of low temperature (-78°C) gamma irradiation was investigated on microbial populations in selected dairy products to determine the irradiation dosage needed to produce commercially sterile dairy products for immunosuppressed patients. 40 kGy irradiation was sufficient to sterilize ice cream and frozen yogurt, but not mozzarella or Cheddar cheeses. Up to 8 wk continued incubation of the 40 kGy irradiated products at 7°C or 35°C resulted in no resuscitative growth in ice cream or yogurt, but identifiable growth in the cheeses. The 12D for B. cereus preinoculated into cheese and ice cream was 43-50 kGy.     

Influence of Water-Soluble Nitrogen and Free Amino Groups on Sensory Attributes of Smoked Mozzarella Cheese

The smoking of cheeses contributes to significant changes in their color, aroma, and also content of free amino groups. The aim of the study was to evaluate changes in sensory attributes of smoked and unsmoked mozzarella cheese during storage for four weeks. It was found that inner layers of both cheeses were equally light despite large differences in their outer layers (ΔL*: 26.33 for smoked and ΔL*: 5.33 for unsmoked). Color of the edge layer in smoked cheese was more saturated than in unsmoked cheese (ΔC* = 17.47). The edge layer in smoked cheese after storage became more saturated (ΔC* = 5.12). Desirability of smoked cheese was 1.5-fold greater than that of unsmoked cheese. Smoking contributed to the disappearance of cooked aroma (by 32%), whey, and cowy/phenolic aromas and intensified the perceptibility of acid taste (8.5 times). Changes were higher in smoked mozzarella because of its higher proteolysis susceptibility.     

Reduced-fat cheddar cheese manufactured using a novel fat removal process

Normally, reduced-fat Cheddar cheese is made by removal of fat from milk prior to cheese making. Typical aged flavor may not develop when 50% reduced-fat Cheddar cheese is produced by this approach. Moreover, the texture of the reduced-fat cheeses produced by the current method may often be hard and rubbery. Previous researchers have demonstrated that aged Cheddar cheese flavor intensity resides in the water-soluble fraction. Therefore, we investigated the feasibility of fat removal after the aging of Cheddar cheese. We hypothesized the typical aged cheese flavor would remain with the cheese following fat removal. A physical process for the removal of fat from full-fat aged Cheddar cheese was developed. The efficiency of fat removal at various temperatures, gravitational forces, and for various durations of applied forces was determined. Temperature had the greatest effect on the removal of fat. Gravitational force and the duration of applied force were less important at higher temperatures. A positive linear relationship between temperature and fat removal was observed from 20 to 33 degrees C. Conditions of 30 degrees C and 23,500 x g for 5 min removed 50% of the fat. The removed fat had some aroma but little or no taste. The fatty acid composition, triglyceride molecular weight distribution, and melting profile of the fat retained in the reduced-fat cheeses were all consistent with a slight increase in the proportion of saturated fat relative to the full-fat cheeses. The process of fat removal decreased the grams of saturated fat per serving of cheese from 6.30 to 3.11 g. The flavor intensity of the reduced-fat cheeses were at least as intense as the full-fat cheeses.     

Enzyme-Modified Cheese Technology

Enzyme-modified cheese is derived from cheese by enzymatic means. Enzymes may be added during the manufacture of cheese or after aging. An incubation period under controlled conditions is required for proper flavor development. The mechanism of flavor development in enzyme-modified cheese may be related to the curing of cheese. Although many of the mechanisms for flavor development in cheese are not well understood, carbohydrates, proteins, and fat undergo enzymatic degradation during cheese aging, and these reactions are important in the development of flavor in cheese and enzyme-modified cheese. In some instances, the flavor profile or intensity is proportional to the degree of lipolysis and release of low molecular weight free fatty acids as with Romano or Provolone cheese. In other cases, a similar free fatty acid profile enhances both Cheddar flavor and Swiss cheese flavor but is not characteristic for either.Enzyme-modified cheeses are generally added to foods at levels of .1 to 2.0%, although they can be used at 5% of the formulation to add dairy or cheesy notes to foods and to reduce the requirement for aged cheese in food formulations.     

Keto acid decarboxylase and keto acid dehydrogenase activity detected during the biosynthesis of flavor compound 3-methylbutanal by the nondairy adjunct culture Lactococcus lactis ssp. lactis F9

3-Methylbutanal is one of the primary substances that contribute to the nutty flavor in cheese. Lactococcus strains have been shown to have higher aminotransferase and α-keto acid decarboxylase activities compared with other microbes, indicating that they might form a higher amount of 3-methylbutanal by decarboxylation. Several dairy lactococcal strains have been successfully applied as adjunct cultures to increase the 3-methylbutanal content of cheese. Moreover, compared with dairy cultures, the nondairy lactococci are generally metabolically more diverse with more active AA-converting enzymes. Therefore, it might be appropriate to use nondairy lactococcal strains as adjunct cultures to enrich the 3-methylbutanal content of cheese. This study thereby aimed to select a nondairy Lactococcus strain that is highly productive of 3-methylbutanal, identify its biosynthetic pathway, and apply it to cheese manufacture. Twenty wild nondairy lactococci isolated from 5 kinds of Chinese traditional fermented products were identified using 16S rRNA sequence analysis and were found to belong to Lactococcus lactis ssp. lactis. The nondairy strains were then screened in vitro for their production of 3-methylbutanal and whether they met the criteria to become an adjunct culture for cheese. The L. lactis ssp. lactis F9, isolated from sour bamboo shoot, was selected because of its higher 3-methylbutanal production, suitable autolysis rate, and lower acid production. The enzymes involved in the catabolic pathway of leucine were then evaluated. Both α-keto acid decarboxylase (6.96 μmol/g per minute) and α-keto acid dehydrogenase (30.06 μmol/g per minute) activities were detected in nondairy L. lactis F9. Cheddar cheeses made with different F9 levels were ripened at 13°C and analyzed after 90 d by a combination of instrumental and sensory methods. The results showed that adding nondairy L. lactis F9 significantly increased 3-methylbutanal content and enhanced the nutty flavor of the cheese without impairing its textural properties. Thus, nondairy L. lactis F9 efficiently enhanced the biosynthesis of 3-methylbutanal in vitro and in manufactured cheese.     

Study of taste-active compounds in the water-soluble extract of mature Cheddar cheese

The chemical composition of the water-soluble extracts of mature Cheddar cheese were identified, with the emphasis on understanding the interplay of compounds contributing to the savoury taste in Cheddar. The ultra-filtered water-soluble extracts of two mature Cheddar cheeses were fractionated by gel permeation chromatography (GPC). By sensory evaluation, two taste-active GPC fractions were identified from each cheese. On the basis of chemical profiling of these fractions, aqueous model tastant mixtures were prepared and sensory omission tests carried out. Glutamic acid, organic acids and mineral salts were the main tastants, whereas the other amino acids had a limited impact on taste. The characteristic umami taste was explained by a synergistic effect of glutamic acid and salts. Matching umami taste intensities were obtained from different concentrations of glutamic acid and salts. Unmasking of a bitter or sweet taste from mixtures of sub-threshold concentrations of amino acids without glutamic acids was also observed.     

Technical note: At-line prediction of mineral composition of fresh cheeses using near-infrared technologies

Milk and dairy products are important sources of macro- and trace elements for human health. However, fresh cheeses usually have a lower mineral content than other cheeses, and this makes mineral prediction more difficult. Although mineral prediction in several food matrices using infrared spectroscopy has been reported in the literature, very little information is available for cheeses. The present study was aimed at developing near-infrared reflectance (NIR, 866–2,530 nm) and transmittance (NIT, 850–1,050 nm) spectroscopy models to predict the major mineral content of fresh cheeses. We analyzed samples of mozzarella (n = 130) and Stracchino (n = 118) using reference methods and NIR and NIT spectroscopy. We developed prediction models using partial least squares regression analysis, and subjected them to cross- and external validation. Average Na content was 0.15 and 0.22 g/100 g for mozzarella and Stracchino, respectively. The NIR and NIT spectroscopy performed similarly, with few exceptions. Nevertheless, none of the prediction models was accurate enough to replace the current reference analysis. The most accurate prediction model was for the Na content of mozzarella cheese using NIT spectroscopy (coefficient of determination of external validation = 0.75). We obtained the same accuracy of prediction for P in Stracchino cheese with both NIR and NIT spectroscopy. Our results confirmed that mineral content is difficult to predict using NIT and NIR spectroscopy.     

Commercial cheeses with different texture have different disintegration and protein/peptide release rates during simulated in vitro digestion

Solid food disintegration in the stomach has recently been linked to food texture, which changes during digestion. This phenomenon is likely to affect the kinetics of protein digestion and therefore associated postprandial metabolic responses. Depending upon the variety, the cheese protein and lipid content as well as the texture can be modulated, illustrating complexity. Five commercial cheeses, covering a range of textural properties, were selected and characterised. Cheese particles were submitted to an in vitro digestion model to study cheese disintegration and protein/peptide release. Cheese disintegration was affected by cheese texture and composition. At the end of gastric digestion, elastic cheeses (mozzarella) were less disintegrated when compared with ripened and soft cheeses with high fat content (Camembert, aged Cheddar). The protein digestion was different amongst cheeses according to different disintegration rates. Cheese structural and textural properties, attributed to processing parameters, can be used to modulate gastro-intestinal digestion of cheese proteins.