Determination of a nitrogen conversion factor for protein content in Cheddar cheese

Flavoromic determination of lactones in cheddar cheese by GC-MS-olfactometry, aroma extract dilution analysis, aroma recombination and omission analysis

To systematically identify and quantify the γ- and δ-lactones in Cheddar cheeses, 20 samples from three sources (Ireland, the UK and the USA) were analysed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), aroma extract dilution analysis, aroma recombination analysis, and aroma addition/omission analysis. Nine lactones were detected in these samples, and one of these lactones, γ-undecalactone, was identified in Cheddar cheese for the first time. The quantitative results showed that the concentration of lactones in these cheeses usually increased as the length of their maturity period increased. γ-Octalactone, γ-undecalactone, γ-dodecalactone, δ-octalactone, δ-decalactone and δ-dodecalactone were identified as aroma-active substances based on their odour activity values and aroma extract dilution analysis, with flavour dilution factors ranging from 2 to 128. Aroma recombination and omission experiments based on a newly developed deodorised Cheddar matrix further validated the important contributions of these lactones to the overall aroma of Cheddar cheeses. The addition of each lactone to aroma recombination models reduced the aroma intensity of sour and rancid properties to various extents and improved the acceptability of the overall flavour.

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.

Influence of storage time and elevated ripening temperature on the chemical and sensory properties of white Cheddar cheese

Aged cheese is an increasingly popular dairy product. One approach to reduce Cheddar cheese maturation time is by utilizing elevated temperature, despite potential problems including development of imbalanced or off-flavors and negative changes in texture. Therefore, the objective of this study was to evaluate the influence of elevated ripening temperature on chemical and sensory properties of aged white Cheddar cheese. White Cheddar cheese was aged at 7.2, 10, or 12.8 °C for 12 months, with samples evaluated at 2, 5, 8, 10, 11, and 12 months by a trained sensory panel (n = 10). Two consumer sensory panels (n = 120) assessed 8- and 12-month aged cheese for comparison to a commercially available reference sample of the same cheese, aged for 12 months. An electronic tongue methodology was developed for analysis of nonvolatile compounds. Trained panel results showed that 2-month cheeses were described by milkfat flavor and sweet taste, 5-month cheeses were described by nutty aroma and white color, and 8-, 10-, 11-, and 12-month cheeses developed aged characteristics, such as umami and bitter tastes, brothy aroma, and aged flavor. Consumer panel results showed similar overall liking scores for the reference cheese and cheeses aged at 10 or 12.8 °C for both evaluations. The electronic tongue could classify samples according to aging month with a validity value of 92.59%. In conclusion, the electronic tongue served as a valid method of instrumental analysis for Cheddar cheese samples throughout maturation. This study demonstrated that aging white Cheddar cheese for 8 months at an elevated storage temperature of 10 °C produced cheese similar in consumer acceptance to that aged at 7 °C for 12 months. PRACTICAL APPLICATION: This study showed that aged white Cheddar storage at a higher temperature was perceived similarly by consumers as one stored for 1 year at a slightly lower temperature. This may be useful to those in the dairy industry exploring ways to accelerate aging, reducing devoted resources, while still producing an acceptable product. Also, the electronic tongue was effective at distinguishing among aged white Cheddar cheese samples showing another application for this technology.