Cheddar Cheese Flavor Research Articles

Regulation of the pleiotropic transcriptional regulator CodY on the conversion of branched-chain amino acids into branched-chain aldehydes in Lactococcus lactis.

Branched-chain aldehydes are the primary compounds that contribute to the nutty flavor in cheddar cheese. Lactococcus lactis, which is often applied as primary starter culture, is a significant contributor to the nutty flavor of cheddar cheese due to its ability of conversion of BCAAs into branched-chain aldehydes. In the present study, we found that the regulatory role of CodY is crucial for the conversion. CodY acts as a pleiotropic transcriptional regulator via binding to various regulatory regions of key genes. The results presented valuable knowledge into the role of CodY on the regulation and biosynthetic pathway of branched-chain amino acids and the related aldehydes. Furthermore, it provided new insight for increasing the nutty flavor produced during the manufacture and ripening of cheese.

Proteolysis during aging of commercial full-fat and reduced-fat Cheddar cheeses of identical chronological age

<abstract> <p>The evolution of Cheddar cheese flavor and texture is highly dependent on its proteolytic state however, Cheddar cheese is marketed based on its chronological age. Information about the proteolytic age of commercial Cheddar cheese of a given age almost does not exist. The present research challenged the merit of marketing Cheddar cheese according to its chronological age. Full-fat (FF) and Reduced-fat (RF) Cheddar cheeses, of identical chronological age, were aged for 180 days at 5 ℃ and the progression of the proteolytic cascade was investigated and quantified. The accumulation of the cheese N fractions that are soluble at pH 4.6 (4.6SN), soluble in 12% tri-chloroacetic acid (12TCASN), and soluble in 5% phospho-tungstic acid (5PTASN) was quantified along with the accumulation of free L-Glutamic acid (L-Glu). Results indicated that both FF and RF cheeses exhibited very significant among-cheeses differences in accumulation of the investigated fractions (p < 0.05). These significant differences were related to both the concentration of the fractions and the rate at which they accumulated. The results thus reflected significant among-cheeses differences in the inherent proteolytic potential of the cheeses as well as in its manifestation during aging. Results clearly indicated that the chronological age of the investigated cheeses did not reflect their proteolytic age. The results highlighted the need to market Cheddar cheese based on some proteolysis-related quantitative parameters.</p> </abstract>

Enzymolysis Combined with Lactic Acid Bacteria (Lab) Fermentation as Promising Strategies for Cheddar Cheese Flavor Development in Reconstituted Milk System

Enzymolysis Combined with Lactic Acid Bacteria (Lab) Fermentation as Promising Strategies for Cheddar Cheese Flavor Development in Reconstituted Milk System

Characterization of major odor‐active compounds responsible for nutty flavor in Cheddar cheese according to Chinese taste

AbstractA nutty flavor is desirable in Cheddar cheese and is easily accepted by most Chinese consumers. Although compounds responsible for nutty flavor in cheeses have been documented, no final conclusions have been reached. In this study, nine samples of top‐selling Cheddar cheeses in the Chinese market were selected, and the odor‐active compounds responsible for the nutty flavor in these samples were studied by gas chromatography‐mass spectrometry (GC‐MS), gas chromatography‐olfactometry (GC‐O), sensory evaluation, and aroma addition experiment. Forty‐nine volatile flavor compounds were identified by GC‐MS via headspace‐solid‐phase microextraction, and 14 odor‐active compounds were identified by GC‐O. It was determined that 2‐methylbutanal, 3‐methylbutanal, and benzaldehyde contributed to the nutty flavor of Cheddar cheese, according to Chinese tastes. The addition of suitable concentrations of these compounds to a model of Cheddar cheese without nutty flavor resulted in the perception of nutty aroma by sensory analysis. These results indicate that 2‐methylbutanal, 3‐methylbutanal, and benzaldehyde are the key aroma‐active compounds, which could make positive contributions to the nutty flavor of Cheddar cheese and favored by Chinese consumers within a certain concentration range.

Çeşnili Lokum Üretiminde Kapsikum Biber Tozu ve Doğal Peynir Aromasının Kullanım Potansiyeli

Turkish delight, which is produced from sugar, starch and water as raw materials and can be enriched with different flavors and aromas, is a traditional dessert widely consumed around the world. Although there are many types of Turkish delight, capsicum pepper powder (CPP) and natural cheese aroma (NCA) added Turkish delights are not consumed in Turkey. In this study, the potential use of CPP and NCA in the production of flavored Turkish delights was studied to obtain a unique taste, flavor and color, and also the physical, chemical and sensorial properties of Turkish delights containing three different ratios of CPP and NCA were determined. For this purpose, capsicum pepper was dried and powdered, and commercial natural Cheddar cheese flavor was used to provide cheesy characteristic to Turkish delights. In capsicum pepper and cheese flavored Turkish delights, the ratios of CPP were 0.1, 0.3 and 0.5% (w/w) while the ratios of NCA were 6.5, 10.0 and 12.5% (w/w). The physicochemical properties such as color, dry matter and ash contents, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities and the sensory properties of Turkish delight samples were determined. The highest L* values were found in Turkish delights with 6.5% and 10.0% NCA concentrations (p0.05). Sensory analysis results indicated that Turkish delights containing 12.5% NCA had a high acceptability score, and CPP added Turkish delights were equally liked by panelists. In conclusion, CPP and NCA flavorings could be used in the production of Turkish delights for the development of a novel dessert product with a high consumer acceptability, and might provide health beneficial functional components.

Sensory characterization of specific wood smoke aromas and their contributions to smoked Cheddar cheese flavor

AbstractThis study characterized the sensory properties of different wood smokes and their application to smoked Cheddar cheese flavor. Sniff jars of wood smokes were created by exposing filter paper to 23°C smoke (cold smoke). Sensory attributes for nine wood smokes (apple, alder, cedar, cherry, hickory, maple, mesquite, oak, and pecan) were generated by a trained panel followed by projective mapping of the different wood smoke aromas. Four distinct wood smokes (mesquite, cherry, hickory, and cedar) were selected for cold smoking of 30 day old Cheddar cheeses. Cheeses were cold smoked at 23°C followed by descriptive analysis of flavor attributes using the trained panel. Nonparametric and parametric statistical analyses were applied to the collected data. Twelve attributes were selected to describe wood smoke aromas. The sensory descriptors for the cold smokes cited most often included: sweet aromatic, charcoal/charred, guaiacol, meaty, vanillin, and fresh tobacco. Mesquite, cherry, hickory, and cedar smokes were the most distinct smokes by projective mapping, and these smokes also imparted distinct flavors to smoked Cheddar cheeses. The mesquite smoked cheese was characterized by high smoke aroma and the highest meaty/brothy flavor, the cherry smoked cheese was distinguished by campfire/marshmallow flavor, the hickory smoked cheese had high campfire/marshmallow and meaty flavors, and the cedar smoked cheese was characterized by an intense resinous flavor. The determination of sensory properties of different wood smokes demonstrates the differences in specific smoke flavor contributions to cheese. Furthermore, the determination of the sensory properties specific to smoked cheese will provide a platform to understand consumer perception of smoked cheeses.Practical ApplicationsSmoked foods are a growing category. This study demonstrated that smokes from different wood sources have distinct aromas that can be differentiated and that these distinct smoke aromatics are imparted to cheeses exposed to different wood smokes. Results from this study provide a sensory language to differentiate aromatics from different wood smokes and may be useful to product developers and food manufacturers seeking to position and differentiate smoked foods.

Exopolysaccharide producing Lactobacillus plantarum SKT109 as adjunct culture in Cheddar cheese production

In vitro antioxidant activity of an exopolysaccharide from Lactobacillus plantarum SKT109 (L-EPS) and potential application of this strain for Cheddar cheese production were evaluated. Cheddar cheese was manufactured using a cheese starter culture consisting of lactococci combined with L. plantarum SKT109 as an adjunct culture. The chemical composition, microbial changes, proteolysis, textural profiles and volatile compounds of the cheeses were studied during 12 weeks of ripening. The experimental cheese made with L. plantarum SKT109 as an adjunct had greater moisture contents than those of the control cheese made with starter alone. L. plantarum SKT109 survived well in Cheddar cheese, with counts of 7.89 log cfu/g at the end of the ripening period. Inclusion of the adjunct strain had no detectable negative effects on cheeses in terms of proteolysis and texture. L. plantarum SKT109 improved the Cheddar cheese flavor profile by increasing the levels of low threshold value compounds including ethyl acetate, 3-methyl-1-butanol, 3-hydroxy-2-butanone and butanone. L-EPS had the strongest scavenging activity toward hydroxyl (68.52%) radicals at a dose of 5 mg/mL. These results indicated that EPS-producing L. plantarum SKT109 or its EPS may be promising ingredients, with favorable effects on cheese texture and flavor as well as potential health benefits.

Evaluation of the Potential of Lactobacillus paracasei Adjuncts for Flavor Compounds Development and Diversification in Short-Aged Cheddar Cheese.

The non-starter microbiota of Cheddar cheese mostly comprises mesophilic lactobacilli, such as Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, and Lactobacillus plantarum. These bacteria are recognized for their potential to improve Cheddar cheese flavor when used as adjunct cultures. In this study, three strains of L. paracasei (DPC2071, DPC4206, and DPC4536) were evaluated for their contribution to the enhancement and diversification of flavor in short-aged Cheddar cheese. The strains were selected based on their previously determined genomic diversity, variability in proteolytic enzyme activities and metabolic capability in cheese model systems. The addition of adjunct cultures did not affect the gross composition or levels of lipolysis of the cheeses. The levels of free amino acids (FAA) in cheeses showed a significant increase after 28 days of ripening. However, the concentrations of individual amino acids in the cheeses did not significantly differ except for some amino acids (aspartic acid, threonine, serine, and tryptophan) at Day 14. Volatile profile analysis revealed that the main compounds that differentiated the cheeses were of lipid origin, such as long chain aldehydes, acids, ketones, and lactones. This study demonstrated that the adjunct L. paracasei strains contributed to the development and diversification of compounds related to flavor in short-aged Cheddar cheeses.

Use of smear bacteria and yeasts to modify flavour and appearance of Cheddar cheese

The strains Staphylococcus saprophyticus DPC5671 and Corynebacterium casei DPC5298 were applied in combination with Debaryomyces hansenii DPC6258 to the surface of young Cheddar cheese curd to obtain two different smear-ripened cheeses. A surface microbiota developed over the incubation period, comprising of both yeast and bacteria; pulsed field gel electrophoresis confirmed that the inoculated strains of S. saprophyticus DPC5671 or C. casei DPC5298 were the dominant bacterial strains on the surface of the cheese at the end of the ripening period. The smear cultures changed the appearance and aroma, which were significantly different from the control cheese. The approach presented in this study represents a method for the development of new cheese varieties with novel aromas within a short ripening time.

Evidence of terroir in milk sourcing and its influence on Cheddar cheese

The concept of local food is rapidly gaining importance within the United States. The foundation of local food is terroir, which links a food to its production environment. The purpose of this study was to investigate evidence of terroir in milk sourcing and its influence on Cheddar cheese flavor. Specifically, the study was designed to assess if consumers could differentiate between Cheddar cheeses made with milk from different dairy farms. Milk from 5 locations, including single dairy farms and commingled sites, was collected from around the state of Oregon. Using raw and pasteurized counterparts of the milk, Cheddar cheese was made and aged. At 5 and 9mo into aging, Cheddar cheese consumers were asked to group the samples based on perceived similarity/dissimilarity of cheese flavor. Grouping data were subjected to multidimensional scaling and subsequent cluster analysis. Results at 5mo into aging revealed that cheeses made by milk originating from different farms (80km apart) within the same region were perceived as different, whereas cheeses made with milk from neighboring farms (5km apart) were grouped together, irrespective of heat treatment (i.e., raw vs. pasteurized). Cheeses made with commingled milk from different regions grouped together. At 9mo of aging, in contrast, a clear separation of perceived flavor was present between the pasteurized and raw cheese samples, whereas the effect of milk sourcing was less pronounced. These data suggest that the geographical location of the milk source has an effect on the flavor of Cheddar cheese, but that the practices of milk commingling and heat treatment likely reduce the effect of geographical location, particularly as cheese ages.

The mathematical modelling of cheese ripening

A mathematical model is developed for the ripening of cheese. Such models may assist predicting final cheese quality using measured initial composition. The main constituent chemical reactions are described with ordinary differential equations. Numerical solutions to the model equations are found using Matlab. Unknown parameter values have been fitted using experimental data available in the literature. The results from the numerical fitting are in good agreement with the data. Statistical analysis is performed on near infrared data provided to the MISG. However, due to the inhomogeneity and limited nature of the data, not many conclusions can be drawn from the analysis. A simple model of the potential changes in acidity of cheese is also considered. The results from this model are consistent with cheese manufacturing knowledge, in that the pH of cheddar cheese does not significantly change during ripening. References D. Dawson and J. Feagan, Bacteriology of cheddar cheese: A study of starter organisms in manufacture and maturing. J. Dairy Res. 24 , 210–224, 1957. M.A. Drake, R.E. Miracle and D.J. McMahon, Impact of fat reduction on flavor and flavor chemistry of Cheddar cheeses. Journal of Dairy Science 93 , 5069–5081, 2010. M. Fenelon and T. Guinee, Primary proteolysis and textural changes during ripening in cheddar cheeses manufactured to different fat contents. Int. Dairy J. 10 , 151–158, 2000. R. Hutkins and N. Nannen, pH homeostasis in lactic acid bacteria. J. Dairy Sci. 76 , 2354–2365, 1992. M. Johnson, Cheese pH–-what's behind the rise and fall? Technical Report 14, Wisconsin Center for Dairy Research, December 2002. J.K. Kim, K. Starzak, G.W. Preckshot, R. Marshall and R.K. Bajpai, Critical reactions in ripening of cheeses–-a kinetic analysis. Appl. Biochem. Biotech. 45 , 51–68, 1994. B.A. Law and A.S. Wigmore, Microbial proteinases as agents for accelerated cheese ripening. Int. J. Dairy Tech. 35 , 75–76, 2007. R. Lawrence, L. Creamer, and J. Gilles, Texture development during cheese ripening. J. Dairy Sci. 70 , 1748–1760, 1987. R. Marsili, Monitoring chemical changes in cheddar cheese during aging by high performance liquid chromatography and gas chromatography techniques. Journal of Dairy Science 68 , 3155–3161, 1985. K. Presser, D. Ratkowsky, and T. Ross, Modelling the growth rate of Escherichia coli as a function of pH and lactic acid concentration. Appl. Environ. Microbiol. 63 , 2355–2360, 1997. S. Rehman, D. Waldron, and P. Fox, Effect of modifying lactose concentration in cheese curd on proteolysis and in quality of Cheddar cheese. Int. Dairy J. 14 , 591–597, 2004. T. Singh, M. Drake, and K. Cadwallader, Flavour of cheddar cheese: A chemical and sensory perspective. Compr. Rev. Food Sci. F. 2 , 166–189, 2003. S. Toelstede and T. Hofmann, Kokumi-active glutamyl peptides in cheeses and their biogeneration by Penicillium roquefortii. Agric. Food Chem. 13 , 3738–3748, 2009.

Texture, flavor, and sensory quality of buffalo milk Cheddar cheese as influenced by reducing sodium salt content

The adverse health effects of dietary sodium demand the production of cheese with reduced salt content. The study was aimed to assess the effect of reducing the level of sodium chloride on the texture, flavor, and sensory qualities of Cheddar cheese. Cheddar cheese was manufactured from buffalo milk standardized at 4% fat level by adding sodium chloride at 2.5, 2.0, 1.5, 1.0, and 0.5% (wt/wt of the curd obtained). Cheese samples were ripened at 6 to 8°C for 180 d and analyzed for chemical composition after 1 wk; for texture and proteolysis after 1, 60, 120, and 180 d; and for volatile flavor compounds and sensory quality after 180 d of ripening. Decreasing the salt level significantly reduced the salt-in-moisture and pH and increased the moisture-in-nonfat-substances and water activity. Cheese hardness, toughness, and crumbliness decreased but proteolysis increased considerably on reducing the sodium content and during cheese ripening. Lowering the salt levels appreciably enhanced the concentration of volatile compounds associated with flavor but negatively affected the sensory perception. We concluded that salt level in cheese can be successfully reduced to a great extent if proteolysis and development of off-flavors resulted by the growth of starter and nonstarter bacteria can be controlled.

Production of Low Fat Cheddar Cheese Made Using Exopolysaccharide-Producing Cultures and Selected Ripening Cultures

Low fat cheeses often suffer from undesirable texture and flavor. The objective of this study is to improve the yield, texture, flavor and quality of low fat Cheddar cheese during ripening using exopolysaccharide-producing lactobacilli and ripening cultures. The article represents one of the first attempts to tackle both texture and flavor at the same time. The study reveals the effect of aging on the texture and flavor of low fat Cheddar cheese over a ripening period of six months. The cheese manufactured with a modified protocol using EPS-producing cultures and ripening cultures showed higher values for moisture content (45%) and yield (9.4%) when compared to cheese manufactured with the conventional procedure and without the addition of EPS-producing cultures and ripening cultures (37.7%) and (4.9%) respectively. The obtained results indicated a 70% decrease in the fat content of the cheese. Texture profile analysis (TPA) indicated that the hardness, the cohesiveness, the springiness, the gumminess and the chewiness of the cheeses made using the EPS-producing cultures decreased with aging. The texture of the ripened low fat cheese made using EPS-producing cultures was described as chewy, springy, cohesive and smooth. The use of the ripening cultures resulted in the elimination of the bitter flavor defect which is a common problem in low fat Cheddar.

Informatic prediction of Cheddar cheese flavor pathway changes due to sodium substitution

Increased interest in reduced and low sodium dairy foods generates flavor issues for cheeses. Sodium is partly replaced with potassium or calcium to sustain the salty flavor perception, but the other cations may also alter metabolic routes and the resulting flavor development in aged cheeses. The effect of some cations on selected metabolic enzyme activity and on lactic acid bacterial physiology and enzymology has been documented. Potassium, for example, is an activator of 40 enzymes and inhibits 25 enzymes. Currently, we can visualize the effects of these cations only as lists inside metabolic databases such as MetaCyc. By visualizing the impact of these activating and inhibitory activities as biochemical pathways inside a metabolic database, we can understand their relevance, predict, and eventually dictate the aging process of cheeses with cations that replace sodium. As examples, we reconstructed new metabolic databases that illustrate the effect of potassium on flavor-related enzymes as microbial pathways. After metabolic reconstruction and analysis, we found that 153 pathways of lactic acid bacteria are affected due to enzymes likely to be activated or inactivated by potassium. These pathways are primarily linked to sugar metabolism, acid production, and amino acid biosynthesis and degradation that relate to Cheddar cheese flavor.

Physicochemical and sensory characterization of Cheddar cheese with variable NaCl levels and equal moisture content

The present study investigated the effect of salt (NaCl) on the flavor and texture of Cheddar cheese with the particular aim to elucidate consequences of, and strategies for, reducing the salt concentration. Descriptive sensory analysis and physicochemical mapping of 9-mo-old Cheddar cheeses containing 0.9, 1.3, 1.7, and 2.3% salt and an equal level of moisture (37.6±0.1%) were undertaken. Moisture regulation during manufacture resulted in slightly higher calcium retention (158 to 169mmol/kg) with decreasing NaCl concentration. Lactose was depleted only at 0.9 and 1.3% salt, resulting in concomitantly higher levels of lactate. Lower levels of casein components and free amino acids were observed with decreasing NaCl concentration, whereas levels of pH 4.6-soluble peptides were higher. Key taste-active compounds, including small hydrophobic peptides, lactose, lactate, and free amino acids, covaried positively with bitter, sweet, sour, and umami flavor intensities, respectively. An additional direct effect of salt due to taste–taste enhancement and suppression was noted. Sensory flavor profiles spanned a principal component dimension of palatability projecting true flavor compensation of salt into the space between cheeses containing 1.7 and 2.3% salt. This space was characterized by salt, umami, sweet, and a range of sapid flavors, and was contrasted by bitter and other off-flavors. Rheological and sensory measurements of texture were highly correlated. Cheeses made with 2.3% salt had a longer and slightly softer texture than cheeses containing 0.9, 1.3, and 1.7% salt, which all shared similar textural properties. Moisture regulation contributed to restoring the textural properties upon a 50% reduction in salt, but other factors were also important. On the other hand, significant flavor deterioration occurred inevitably. We discuss the potential of engineering a favorable basic taste profile to restore full palatability of Cheddar with a 50% reduction in salt.

EVALUATION OF KEY FLAVOR COMPOUNDS IN REDUCED- AND FULL-FAT CHEDDAR CHEESES USING SENSORY STUDIES ON MODEL SYSTEMS

Recent flavor chemistry studies have identified flavor compounds at different concentrations in full- and low-fat Cheddar cheeses. The specific flavor contributions of these compounds in full- and low-fat cheese matrices have not been established. The purpose of this study was to evaluate the sensory response of Cheddar flavor compounds in model full-fat and 75% reduced-fat cheeses. Odor activity values (OAVs) for each compound in full- and reduced-fat cheeses were calculated. Each compound was then added to model cheeses created from 3-week-old full- and reduced-fat Cheddar cheeses. A trained sensory panel (n = 8) evaluated the sensory properties of the cheese models. The final combination of compounds was incorporated into reduced-fat cheese models, and consumers (n = 85) evaluated perceived-aged Cheddar cheese aroma. Based on OAVs and perception of the individual compounds in cheese models, 12 key flavor compounds were identified. Target ideal concentrations of specific cheese flavor compounds in 75% reduced-fat cheese were determined. According to consumers, the perceived aged Cheddar cheese aroma intensity of reduced-fat model cheese with these added compounds was not different (P > 0.05) from the perceived Cheddar cheese aroma intensity of commercial aged full-fat Cheddar cheeses. PRACTICAL APPLICATION The market for reduced-fat Cheddar cheese is increasing as consumers become more health conscious. The structure and biochemistry of reduced-fat Cheddar cheeses are altered, and flavor and texture remain a challenge. This study established the role of 23 volatile compounds using descriptive analysis of cheese model systems. The impact of key compound concentration differences and how these differences affect sensory perception of cheese flavor in full- and 75% reduced-fat Cheddar cheeses were determined. These results provide guidance for mimicking aged Cheddar cheese flavor in reduced-fat cheese.

Mapping Differences in Consumer Perception of Sharp Cheddar Cheese in the United States

There is tremendous variability in flavor profiles of sharp or aged U.S. cheddar cheese due to varied practices among commercial facilities and the lack of legal definitions for these terms. This study explored U.S. consumer perception and liking of commercial sharp or aged cheddar cheese profiles. Flavor profiles of 29 representative sharp cheddar cheeses were documented by descriptive sensory analysis with a trained panel. A total of 9 representative cheddar cheeses were selected and evaluated by consumers in 3 regional locations: east coast (Raleigh, N.C.; n = 150), midwest (Champaign, Ill.; n = 75), and west coast (Pullman, Wash.; n = 100). Consumers assessed the cheeses for overall liking and other consumer liking attributes. External preference mapping revealed 5 distinct consumer segments. The segment membership distribution between east coast and midwest consumers was similar while the west coast distribution was distinct (P < 0.05). A larger proportion of west coast consumers were present in segment 3, which consisted of consumers with specific likes for cheeses characterized by intense flavors of free fatty acid, brothy, and nutty flavors and salty and sour tastes. Consumer preferences in other segments differed from segment 3 due to their liking of at least 1 sensory attribute generally associated with young or mild cheddar cheese flavor. Key drivers of liking for these segments included whey flavor for segments 1 and 4 and milkfat flavor for segment 5. Segment 2 consumers liked most of the cheeses tested except those with dominant whey flavor. A sharp or aged cheddar cheese label means different things to different consumers and liking profiles are not defined by consumer location.

Cheddar cheese classification based on flavor quality using a novel extraction method and Fourier transform infrared spectroscopy

Analysis of Cheddar cheese flavor using trained sensory and grading panels is expensive and time consuming. A rapid and simple solvent extraction procedure in combination with Fourier transform infrared spectroscopy was developed for classifying Cheddar cheese based on flavor quality. Fifteen Cheddar cheese samples from 2 commercial production plants were ground into powders using liquid nitrogen. The water-soluble compounds from the cheese powder, without interfering compounds such as fat and protein, were extracted using water, chloroform, and ethanol. Aliquots (10μL) of the extract were placed on a zinc selenide crystal, vacuum dried, and scanned in the mid-infrared region (4,000 to 700cm−1). The infrared spectra were analyzed by soft independent modeling of class analogy (SIMCA) for pattern recognition. Sensory flavor quality of these cheeses was determined by trained quality assurance personnel in the production facilities. The SIMCA models provided 3-dimensional classification plots in which all the 15 cheese samples formed well-separated clusters. The orientation of the clusters in 3-dimensional space correlated well with their cheese flavor characteristics (fermented, unclean, low flavor, sour, good Cheddar, and so on). The discrimination of the samples in the SIMCA plot was mainly due to organic acids, fatty acids and their esters, and amino acids (1,450 to 1,350 and 1,200 to 990cm−1), which are known to contribute significantly to cheese flavor. The total analysis time, including the sample preparation time, was less than 20min per sample. This technique can be a rapid, inexpensive, and simple tool to the cheese industry for predicting the flavor quality of cheese.

Optimization of headspace solid-phase microextraction for the analysis of specific flavors in enzyme modified and natural Cheddar cheese using factorial design and response surface methodology

A headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC/MS) method was developed using experimental designs to quantify the flavor of commercial Cheddar cheese and enzyme-modified Cheddar cheese (EMCC). Seven target compounds (dimethyl disulfide, hexanal, hexanol, 2-heptanone, ethyl hexanoate, heptanoic acid, δ-decalactone) representative of different chemical families frequently present in Cheddar cheese were selected for this study. Three types of SPME fibres were tested: Carboxen/polydimethylsiloxane (CAR/PDMS), polyacrylate (PA) and Carbowax/divinylbenzene (CW/DVB). NaCl concentration and temperature, as well as extraction time were tested for their effect on the HS-SPME process. Two series of two-level full factorial designs were carried out for each fibre to determine the factors which best support the extraction of target flavors. Therefore, central composite designs (CCDs) were performed and response surface models were derived. Optimal extraction conditions for all selected compounds, including internal standards, were: 50 min at 55 °C in 3 M NaCl for CAR/PDMS, 64 min at 62 °C in 6 M NaCl for PA, and 37 min at 67 °C in 6 M NaCl for CW/DVB. Given its superior sensitivity, CAR/PDMS fibre was selected to evaluate the target analytes in commercial Cheddar cheese and EMCC. With this fibre, calibration curves were linear for all targeted compounds (from 0.5 to 6 μg g −1), except for heptanoic acid which only showed a linear response with PA fibres. Detection limits ranged from 0.3 to 1.6 μg g −1 and quantification limits from 0.8 to 3.6 μg g −1. The mean repeatability value for all flavor compounds was 8.8%. The method accuracy is satisfactory with recoveries ranging from 97 to 109%. Six of the targeted flavors were detected in commercial Cheddar cheese and EMCC.

The Effect of Evening Primrose Oil on Chemical and Blood Cholesterol Lowering Properties of Cheddar Cheese Seoul 139-742, Korea.

The present study was carried out to investigate the changes in chemical and sensory properties, and cholesterol lowering effect of evening primrose oil (EPO) addition in cholesterol-reduced Cheddar cheese. The cholesterol removal rate reached 92.07% by β-cyclodextrin in the cheese before EPO addition. The thiobarbituric acid (TBA) value of cholesterol-reduced and EPO- added cheese increased with both ripening time and amount of EPO addition. Addition of 5% EPO resulted in a significant difference in TBA value after 4-week ripening, compared with no addition of EPO. The production of short-chain free fatty acids (FFAs) increased with ripening period in all treatments. From 4 week of ripening, the amounts of short-chain FFA in 3 and 5% EPO-added groups were significantly higher than those in other groups. Among sensory characteristics, rancidity was mostly affected by EPO addition, however, the rancidity value of 1% EPO-added was not significantly different from that of EPO-free and cholesterol-reduced cheese. Also, Cheddar cheese flavor was not profoundly affected by 1% EPO addition in all ripening periods. Total blood cholesterol dramatically decreased from 184.0 to 137.1 mg/dL with 5% EPO-added and cholesterol-reduced cheese following 8 weeks of feeding. The present results indicated that 5% EPO addition resulted in a profound lowering effect on blood total cholesterol with some adverse effects on chemical and sensory properties. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 3 : 450-458)