Commercial Cheddar Cheese Research Articles

The utility of a slice defect score method in understanding factors impacting the sliceability of commercial Cheddar cheese blocks

A slice defect score method was used to evaluate slicing ability of commercial Cheddar cheese blocks with varying extent of proteolysis. The extent of proteolysis was analysed using urea PAGE and pH 4.6 soluble nitrogen. Cheese blocks were sliced using a food slicer into 0.5, 1, 1.5 or 2-mm thicknesses and two shapes, i.e., square and triangular. Cheese slices were graded for slice quality using a five-point slice defect score. Slices with 2 mm thickness, square shape and less mature Cheddar had the lowest slice defects score due to rigidity, absence of cracks and pinholes due to fewer stress concentration points and higher amount of intact casein. The slice defect score method differentiated cheese blocks well for sliceability, depending upon the desired shape and thickness of the cheese slices. The finding of this work will help develop a more comprehensive quantitative tool for assessing the slicing ability of cheese blocks.

Identifying Chemical Differences in Cheddar Cheese Based on Maturity Level and Manufacturer Using Vibrational Spectroscopy and Chemometrics.

Cheese is a nutritious dairy product and a valuable commodity. Internationally, cheddar cheese is produced and consumed in large quantities, and it is the main cheese variety that is exported from Australia. Despite its importance, the analytical methods to that are used to determine cheese quality rely on traditional approaches that require time, are invasive, and which involve potentially hazardous chemicals. In contrast, spectroscopic techniques can rapidly provide molecular information and are non-destructive, fast, and chemical-free methods. Combined with partner recognition methods (chemometrics), they can identify small changes in the composition or condition of cheeses. In this work, we combined FTIR and Raman spectroscopies with principal component analysis (PCA) to investigate the effects of aging in commercial cheddar cheeses. Changes in the amide I and II bands were the main spectral characteristics responsible for classifying commercial cheddar cheeses based on the ripening time and manufacturer using FTIR, and bands from lipids, including β'-polymorph of fat crystals, were more clearly determined through changes in the Raman spectra.

Isolation of casein for stable isotope ratio analysis of butter, cheese, and milk powder.

Stable isotope ratio analysis (SIRA) is commonly used for the authentication of dairy commodities, providing evidence to support the geographical origin and production background of products. We set out to optimise methods for the isolation of a common constituent (casein) from three dairy commodities, which would permit easier inter- and intra-commodity comparisons following SIRA. Three published methods for isolation of protein (from cheese, milk, and butter) were adapted to yield protein (casein) fractions from commercial cheddar cheese, whole milk powder (WMP), and butter samples with a high degree of purity for subsequent SIRA. The casein fractions isolated underwent elemental analysis (H, C, and N), protein determination, and some also underwent SIRA of O and S. Two-way analysis of variance and Tukey post hoc comparisons tested differences between methods. For each product, an optimised casein isolation method was chosen based on the C/N ratio and protein content. An optimum solvent lipid extraction (petroleum spirit-diethyl ether (2:1)) and casein precipitation method was chosen for cheddar cheese casein. A final solvent lipid extraction (heptane-isopropanol (3:2)) was necessary for WMP and butter casein extraction. δ13 C and δ2 H values validated the methods' abilities to remove contaminating lipid and isolate pure casein. Casein of high purity, for subsequent SIRA, can be isolated from cheddar cheese, WMP, and butter following modifications of previously published methods.

X-ray computerized microtomography and confocal Raman microscopy as complementary techniques to conventional imaging tools for the microstructural characterization of Cheddar cheese.

This study explored the use of X-ray computerized microtomography (micro-CT) and confocal Raman microscopy to provide complementary information to well-established techniques, such as confocal laser scanning microscopy (CLSM), for the microstructural characterization of cheese. To evaluate the potential of these techniques, 5 commercial Cheddar cheese samples, 3 with different ripening times and 2 with different fat contents, were analyzed. Confocal laser scanning microscopy was particularly useful to describe differences in fat and protein distribution, especially between the 2 samples with different fat contents. The quantitative data obtained through image analysis correlated well with the nutritional information provided in the product labels. Conversely, micro-CT was more advantageous for studying the size and spatial distribution of microcrystals present within the cheese matrix. Two types of microcrystals were identified that differed in size, shape, and X-ray attenuation. The smallest, with a diameter of approximately 10 to 20 μm, were more abundant in the samples and presented a more uniform roundish shape and higher X-ray attenuation. Larger and more heterogeneous crystals with diameters reaching 50 μm were also observed in scarcer numbers and showed lower X-ray attenuation. Confocal Raman microscopy was useful not only for identifying the distribution of all these components but also allowed comparing the presence of micronutrients such as carotenoids in the cheeses and provided compositional information on the crystals detected. Small and large crystals were identified as calcium phosphate and calcium lactate, respectively. Overall, using micro-CT, confocal Raman microscopy, and CLSM in combination generated novel and complementary information for the microstructural and nutritional characterization of Cheddar cheese. These techniques can be used to provide valuable knowledge when studying the effect of milk composition, processing, and maturation on the cheese quality attributes.

Identification of aroma-active compounds in Cheddar cheese imparted by wood smoke

Cheddar cheese is the most popular cheese in the United States, and the demand for specialty categories of cheese, such as smoked cheese, are rising. The objective of this study was to characterize the flavor differences among Cheddar cheeses smoked with hickory, cherry, or apple woods, and to identify important aroma-active compounds contributing to these differences. First, the aroma-active compound profiles of hickory, cherry, and apple wood smokes were analyzed by solid-phase microextraction (SPME) gas chromatography-olfactometry (GCO) and gas chromatography-mass spectrometry (GC-MS). Subsequently, commercial Cheddar cheeses smoked with hickory, cherry, or apple woods, as well as an unsmoked control, were evaluated by a trained sensory panel and by SPME GCO and GC-MS to identify aroma-active compounds. Selected compounds were quantified with external standard curves. Seventy-eight aroma-active compounds were identified in wood smokes. Compounds included phenolics, carbonyls, and furans. The trained panel identified distinct sensory attributes and intensities among the 3 cheeses exposed to different wood smokes (P < 0.05). Hickory smoked cheeses had the highest intensities of flavors associated with characteristic "smokiness" including smoke aroma, overall smoke flavor intensity, and meaty, smoky flavor. Cherry wood smoked cheeses were distinguished by the presence of a fruity flavor. Apple wood smoked cheeses were characterized by the presence of a waxy, green flavor. Ninety-nine aroma-active compounds were identified in smoked cheeses. Phenol, guaiacol, 4-methylguaiacol, and syringol were identified as the most important compounds contributing to characteristic "smokiness." Benzyl alcohol contributed to the fruity flavor in cherry wood smoked cheeses, and 2-methyl-2-butenal and 2-ethylfuran were responsible for the waxy, green flavor identified in apple wood smoked cheeses. These smoke flavor compounds, in addition to diacetyl and acetoin, were deemed important to the flavor of cheeses in this study. Results from this study identified volatile aroma-active compounds contributing to differences in sensory perception among Cheddar cheeses smoked with different wood sources.

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

&lt;abstract&gt; &lt;p&gt;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 &amp;lt; 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.&lt;/p&gt; &lt;/abstract&gt;

The key aroma compounds and sensory characteristics of commercial Cheddar cheeses

To study the key aroma components and flavor profile differences of Cheddar cheese with different maturity and from different countries, the flavor components of 25 imported commercial Cheddar cheese samples in the China market were determined by gas chromatography-mass spectrometry. The quality and quantity of 40 flavor compounds were analyzed by gas chromatography-olfactometry among 71 aroma compounds determined by gas chromatography-mass spectrometry. Combined with odor activity value calculation, principal component analysis (PCA) was conducted to analyze the relationship among 26 flavor compounds with odor activity values >1 and the maturity of Cheddar cheese. The PCA results showed significant differences between the group of mild Cheddar cheese and the groups of medium Cheddar cheese and mature Cheddar cheese, and no significant differences were observed between medium Cheddar cheese and mature Cheddar cheese. According to the results of PCA and consumers' preference test, representative Cheddar cheese samples with different ripening times were selected for the flavor profile analysis. Partial least squares regression analysis was conducted to obtain the relationship between sensory properties and flavor compounds of different Cheddar cheeses. Based on partial least squares regression analysis, 1-octen-3-one, hexanal, acetic acid, 3-methylindole, and acetoin were positively correlated with milky, sour, and yogurt of mild Cheddar cheese. Dimethyl trisulfide, phenylacetaldehyde, ethyl caproate, octanoic acid, and furaneol and other compounds were positively correlated with fruity, caramel, rancid, and nutty notes of the medium and mature Cheddar cheeses.

Population dynamics of coliforms in a commercial Cheddar cheese production facility

The detection of coliforms in young cheese is a potential indication of undesirable microbial growth within the processing environment. The aim of this study was to investigate sources and conditions that lead to the intermittent detection of coliforms (1-3 log cfu/g) in young Cheddar cheese at a single commercial facility. Analysis of historical production data, in combination with iterative investigative sampling events, was performed to determine coliform levels in milk, whey, curd, and surfaces at the beginning, middle, and end of the production day. After sanitation, conveyor belt pieces from the draining and matting conveyor (DMC) were collected and evaluated for bacterial survivors using culture-based methods and scanning electron microscopy. Production data analysis indicated that cheese produced later in the production day (≥16 h) was significantly more likely to test positive for coliforms than cheese made earlier in the production day (<12 h). Enumeration of coliforms in raw and heat-treated milk demonstrated that the subpasteurization thermal treatment (67-70°C, 26-28 s) was effective at reducing, but not eliminating, coliforms. Repeated sampling identified the DMC, particularly the drain belt and belt 1, as a critical area that supported coliform growth during the production day. Coliform levels in whey entering the weir maintained a level of <1 cfu/mL throughout production; however, coliform levels in whey below the drain belt increased from <1 cfu/mL at midday (8 h) to 5.04 log cfu/mL by the end of the production day (~18 h). Routine sanitation inside the DMC resulted in undetectable coliform levels on easily accessible surfaces. However, enrichment and scanning electron microscopy of belt sections revealed pockets of viable coliforms and other bacteria in cracks and defects in conveyor belts, indicating that sanitation did not eliminate all viable bacteria. Low levels of coliforms are present in heat-treated milk and survive sanitation in the DMC and could serve as the initial seed for high levels of coliforms at the end of the production day.

Growth potential and biofilm development of nonstarter bacteria on surfaces exposed to a continuous whey stream

Commercial Cheddar cheese production uses an automated, continuous production system that provides favorable conditions for specific undesirable bacterial subpopulations in certain sections of the processing system. The draining and matting conveyor (DMC) is a large, fully enclosed series of conveyor belts that separates curd and whey on the first drain belt and supports the cheddaring process in subsequent sections. In a previous study, we demonstrated that coliforms increase in the draining section of the DMC (pH 6.0-6.3, 36°C) over a typical 18-h production shift and can lead to detectable coliforms in finished cheese. Sampling at the commercial plant indicated 2 sources of very low levels of coliforms: (1) subpasteurized whey and curd entering the DMC and (2) surfaces in the DMC after sanitation. Mitigation of these sources would require different approaches. The aim of this study was to investigate whether naturally low levels of coliforms in whey could increase in the bulk liquid and attach to different surface materials within 18 h. A laboratory-scale system was created to mimic the conditions of the initial draining section of the DMC and consisted of single-pass, naturally contaminated whey (pH 6.3, 35°C) flowing through a bioreactor (1.11 L/h) containing coupons of surface types found in the DMC (stainless steel and polypropylene). Whey inside the bioreactor chamber and surface coupons were enumerated for bacterial subpopulations on selective media for planktonic and attached bacteria, respectively, at 0, 12, 15, and 18 h. Bacterial isolates were identified by 16S rDNA sequencing. Nonstarter bacteria present in the whey at 0 h included coliforms (Enterobacter), Pseudomonas, and Acinetobacter (0.80, 2.55, and 2.32 log cfu/mL, respectively), with each increasing significantly in whey (6.18, 7.00, and 5.89 log cfu/mL) and on coupons (5.20, 6.85, and 5.29 log cfu/cm2, respectively) after 18 h in the continuous flowing system. Scanning electron microscopy confirmed bacterial attachment on both surfaces, with early biofilm development evident on polypropylene coupons by 18 h. Results from this laboratory-scale study demonstrated that naturally low levels of coliforms entering the DMC in the whey could replicate within the conditions of the draining section of the DMC to the levels found in the commercial production environment.

Optimizing the acceleration of Cheddar cheese ripening using response surface methodology by microbial protease without altering its quality features

Cheddar cheese proteolysis were accelerated employing Penicillium candidum PCA1/TT031 protease into cheese curd. In the present study, several of the significant factors such as protease purification factor (PF), protease concentration and ripening time were optimized via the response surface methodology (RSM). The ideal accelerated Cheddar cheese environment consisted of 3.12 PF, 0.01% (v/v) protease concentration and 0.6/3 months ripening time at 10 °C. The RSM models was verified to be the most proper methodology for the maintain of chosen Cheddar cheese. Under this experimental environment, the pH, acid degree value (ADV), moisture, water activity (aw), soluble nitrogen (SN)%, fat and overall acceptability were found to be 5.4, 6.6, 35%, 0.9348, 18.8%, 34% and 13.6, respectively of ideal Cheddar cheese. Furthermore, the predicted and experimental results were in significant agreement, which confirmed the validity and reliability of the suggested method. In spite of the difference between the ideal and commercial Cheddar cheese in the concentration of some of amino acids and free fatty acids, the sensory evaluation did not show any significant difference in aroma profile between them.

Microbiota and Metabolite Profiling Combined With Integrative Analysis for Differentiating Cheeses of Varying Ripening Ages.

Cheese maturation and flavor development results from complex interactions between milk substrates, cheese microbiota and their metabolites. In this study, bacterial 16S rRNA-gene sequencing, untargeted metabolomics (gas chromatography-mass spectrometry) and data integration analyses were used to characterize and differentiate commercial Cheddar cheeses of varying maturity made by the same and different manufacturers. Microbiota and metabolite compositions varied between cheeses of different ages and brands, and could be used to distinguish the cheeses. Individual amino acids and carboxylic acids were positively correlated with the ripening age for some brands. Integration and Random Forest analyses revealed numerous associations between specific bacteria and metabolites including a previously undescribed positive correlation between Thermus and phenylalanine and a negative correlation between Streptococcus and cholesterol. Together these results suggest that multi-omics analyses has the potential to be used for better understanding the relationships between cheese microbiota and metabolites during ripening and for discovering biomarkers for validating cheese age and brand authenticity.

Drivers of liking for Cheddar cheese shreds

The prepackaged cheese shred category has steadily increased over the past few years, and Cheddar shreds represent the highest volume in this category. Recent studies have established extrinsic attributes that drive purchase in this category, but no published studies have addressed the intrinsic flavor and texture properties that drive consumer liking. The objective of this study was to determine the desirable flavor and functional attributes for Cheddar cheese shreds. We conducted a category survey of commercial Cheddar cheese shreds (n = 25, collected in duplicate). We documented sensory properties (shred appearance, flavor, texture, and hot texture) using a trained sensory panel. Analytical instrumental tests performed included shred-size distribution, proximate analysis, sugars (lactose, glucose, galactose), lactic acid, Cheddar meltability, pH, and color. Then, representative shreds (n = 10) were evaluated by cheese shred consumers (n = 151) for overall, appearance, flavor, and texture liking. Analysis of variance, principal component analysis, and external preference mapping were used to interpret results. Shreds were differentiated by color, whey, diacetyl, sulfur, nutty, and brothy flavors, as well as by hot and cold texture attributes and instrumental tests. Mild or medium shreds exhibited greater firmness, stretchability, and elasticity when hot than did sharp shreds. We identified 3 consumer clusters, defined by high acceptance for all Cheddar shreds or preferences for sharp or mild shreds. Bitterness was an overall driver of dislike. Visible powder negatively affected appearance and overall liking for some consumers. Sensory properties strongly affected consumer acceptance and purchase intent for Cheddar cheese shreds. Results from this study can be used to optimize the intrinsic sensory properties of Cheddar cheese shreds.

Rapid classification of commercial Cheddar cheeses from different brands using PLSDA, LDA and SPA–LDA models built by hyperspectral data

This study aimed to investigate the feasibility of using near-infrared hyperspectral imaging (NIR-HSI) technique for classifying commercial Cheddar cheeses from different brands. Three classification models including a probability based partial least squares discriminant analysis (PLSDA), linear discriminant analysis (LDA) and successive projections algorithm (SPA)–LDA were used to discriminate four brands of Cheddar cheeses. A simple sample ranking method was used to improve the performance of these models. The generalisation abilities of the PLSDA, LDA and SPA–LDA models for the classification of new batch cheeses were investigated. The optimal number of PLS components was 24 for PLSDA, while the optimal SPA selected wavelengths was 105 for SPA–LDA. The results showed that PLSDA built by hyperspectral data was the most suitable model for brands classification with correct classification rate of 86.67%, and SPA–LDA had better performance than LDA with corresponding correct classification rates of 83.33% and 76.67%, respectively. As a comparison, models built by physical data (texture and colour) achieved poor classification results ( < 65% for test set). The current result revealed that HSI technique is better and faster than conventional cheese classification methods.

Consumer insights on prepackaged Cheddar cheese shreds using focus groups, conjoint analysis, and qualitative multivariate analysis

This study established attractive attributes and drivers of purchase for prepackaged Cheddar cheese shreds. Seven focus groups of Cheddar cheese shred consumers (n = 61) were conducted to probe consumer beliefs regarding packaging, ingredients, label claims, and applications of prepackaged Cheddar cheese shreds. Subsequently, an online survey was developed utilizing the key attributes from the focus groups. The survey (n = 1,288) included maximum difference scaling, Kano questions, and adaptive choice-based conjoint analysis. Additionally, 9 different commercial Cheddar cheese shreds varying in color, shred thickness, brand, and price were selected for a follow-up qualitative multivariate analysis to gain further consumer insight on attribute importance. Consumers (n = 13) were provided with commercial packages of shreds to evaluate over a 4-week period. Consumers journaled their likes and dislikes after use of each cheese shred and subsequently participated in a final 2.5-h focus group and projective mapping exercise. Consumers placed highest importance on price, followed by nutrition claims, color, sharpness, thickness, and label claims. Four consumer clusters were identified from conjoint utility scores. One consumer cluster exhibited preference for value-added features such as nutrition claims and brand, and another consumer cluster placed importance on shred color, whereas the other 2 groups were driven primarily by price. The qualitative multivariate analysis results confirmed the focus group and survey results: meltability, orange color, lack of clumps, ability to reseal the bag, and desirable "Cheddar" flavor were also preferred Cheddar shred qualities.

Effects of variation in cheese composition and maturation on water activity in Cheddar cheese during ripening

Changes in the water activity (aw) of experimental Cheddar cheeses with different compositions were measured over a 270 d ripening period. The ranges of key compositional parameters were typical of those found in commercial Cheddar cheese: moisture (35.6–38.6%), fat (29.9–33.4%), salt (1.4–2.0%), salt-in-moisture (3.8–5.2%), moisture-in-non-fat substances (MNFS, 52.4–56.3%) and pH (5.0–5.7). Linear regression analysis indicated that at ripening times ≤30 d, the aw was inversely correlated with salt-in-moisture, while at 270 d it was positively correlated with levels of moisture and MNFS, but negatively with fat content. The aw decreased significantly (P < 0.001) during ripening, from a mean of ∼0.965 at 1 d to ∼0.956 at 270 d. The preponderant factor responsible for the decrease in aw was the increase in proteolysis, as measured using pH 4.6 soluble N and free amino acids.

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.

Characterization of aromatic properties of old-style cheese starters

Old-style cheese starters were evaluated to determine their ability to produce cheese aroma compounds. Detailed analyses of the aroma-producing potential of 13 old-style starter cultures were undertaken. The proteolytic profile of the starters was established by an accelerated ripening study using a model cheese slurry and compared with those of a commercial aromatic starter and commercial Cheddar cheeses. To evaluate the aromatic potential of the starter cultures, quantification of free amino acids liberated and volatile compounds after 15 d of ripening at 30°C as well as sensory analysis were carried out. Results showed that proteolysis patterns of all 13 starter cultures in the curd model were comparable to those of commercial Cheddar cheeses. All tested cultures demonstrated the ability to produce high amounts of amino acids recognized as precursors of aroma compounds. Several differences were observed between the starters and commercial Cheddar cheeses regarding some amino acids such as glutamate, leucine, phenylalanine, proline, and ornithine, reflecting the various enzymatic systems present in the starters. Starters Bt (control) and ULAAC-E exhibited various significant differences regarding their free amino acid profiles, as confirmed by sensory analysis. In addition, identification of volatile compounds confirmed the presence of several key molecules related to aroma, such as 3-methylbutanal and diacetyl. Besides the aroma-producing aspect, 2 starters (ULAAC-A and ULAAC-H) seem to possess an important ability to generate large amounts of γ-aminobutyric acid, which contributed up to 15% of the total amino acids present in the model curd after 15 d ripening. γ-Aminobutyric acid is an amine well-known for its antihypertensive and calming effects.

Identification of bioactive peptides in commercial Cheddar cheese

This study examined the presence of antimicrobial, antioxidant and antihypertensive peptides in three commercially available Australian Cheddar cheeses. Peptide extracts as well as fractionated peptide extracts were examined. Commercial cheese A peptides exhibited the greatest inhibition against Bacillus cereus and also commercial cheese A fractionated peptides greater than 10 kDa showed the highest inhibition against B. cereus. Commercial cheese A peptides also showed the highest inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), a free radical used to measure antioxidant activity. All cheese fractionated peptides greater than 10 kDa demonstrated higher inhibition of DPPH after fractionation. Antihypertensive peptides were determined by inhibition of the angiotensin-converting enzyme (ACE). Overall, commercial cheese A had the lowest concentration required to inhibit ACE and commercial cheese A fractionated peptides lower than 5 kDa had the lowest inhibition after fractionation. These preliminary findings suggest that peptide extracts of three commercial Australian Cheddar cheeses exhibit antimicrobial, antihypertensive and antioxidant properties.

Consumer Preferences for Mild Cheddar Cheese Flavors

Flavor is an important factor in consumer selection of cheeses. Mild Cheddar cheese is the classification used to describe Cheddar cheese that is not aged extensively and has a "mild" flavor. However, there is no legal definition or age limit for Cheddar cheese to be labeled mild, medium, or sharp, nor are the flavor profiles or flavor expectations of these cheeses specifically defined. The objectives of this study were to document the distinct flavor profiles among commercially labeled mild Cheddar cheeses, and to characterize if consumer preferences existed for specific mild Cheddar cheese flavors or flavor profiles. Flavor descriptive sensory profiles of a representative array of commercial Cheddar cheeses labeled as mild (n= 22) were determined using a trained sensory panel and an established cheese flavor sensory language. Nine representative Cheddar cheeses were selected for consumer testing. Consumers (n= 215) assessed the cheeses for overall liking and other consumer liking attributes. Internal preference mapping, cluster analysis, and discriminant analysis were conducted. Mild Cheddar cheeses were diverse in flavor with many displaying flavors typically associated with more age. Four distinct consumer clusters were identified. The key drivers of liking for mild Cheddar cheese were: color, cooked/milky, whey and brothy flavors, and sour taste. Consumers have distinct flavor and color preferences for mild Cheddar cheese. These results can help manufacturers understand consumer preferences for mild Cheddar 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.