Reduced-fat Cheddar Research Articles

Factors That Contribute to the Botulinal Safety of Reduced-Fat and Fat-Free Process Cheese Products

The effects of fat, type of natural cheese, and adjunct process cheese ingredients were evaluated to determine factors that contribute to the botulinal safety of reduced-fat (RF) process cheese products stored at 30°C. In the first set of experiments, pasteurized process cheese products (PPCPs) were formulated using full-fat (FF) Cheddar, 30% RF Cheddar, or skim milk (SM) cheese as cheese-base types and were standardized to 59% moisture, pH 5.75, 2.8 or 3.2% total salts, and 15 to 19% fat. Subsequent trials evaluated the effect of fat levels and adjunct ingredients in PPCPs made with SM, RF, and FF cheese (final fat levels, less than 1, 13, and 24%, respectively). When fat levels of PPCPs were comparable (15.1, 19.1, and 16.2 for product manufactured with SC, RF, and FF cheese, respectively), botulinal toxin production was delayed for up to 2 days in PPCPs formulated with SM compared with RF or FF cheese; however, the effect was not statistically significant. When fat levels were reduced to less than 1% in SM PPCPs, toxin production was delayed 2 weeks in products made with SM compared with RF or FF cheese manufactured with 13 or 24% fat, respectively. The antibotulinal effect of adjunct ingredients varied among the products manufactured with different fat levels. Sodium lactate significantly delayed toxin production (P < 0.05) for all fat levels tested, whereas β-glucan fat replacer did not delay toxin production. An enzyme-modified cheese used as a flavor enhancer significantly delayed toxin production (P < 0.05) in SM (less than 1% fat) products but had little to no inhibitory effect in RF (13% fat) and FF (24% fat) cheese products. Similarly, monolaurin increased the time to detectable toxin in SM products but was ineffective in RF or FF cheese products. These results verify that RF PPCPs exhibit greater safety than FF products and that safety may be enhanced by using certain adjunct ingredients as antimicrobials.

Influence of Adjunct Use and Cheese Microenvironment on Nonstarter Bacteria in Reduced-Fat Cheddar-Type Cheese

This study investigated population dynamics of starter, adjunct, and nonstarter lactic acid bacteria (NSLAB) in reduced-fat Cheddar and Colby cheese made with or without a Lactobacillus casei adjunct. Duplicate vats of cheese were manufactured and ripened at 7°C. Bacterial populations were monitored periodically by plate counts and by DNA fingerprinting of cheese isolates with the random amplified polymorphic DNA technique. Isolates that displayed a unique DNA fingerprint were identified to the species level by partial nucleotide sequence analysis of the 16S rRNA gene. Nonstarter biota in both cheese types changed over time, but populations in the Colby cheese showed a greater degree of species heterogeneity. The addition of the L. casei adjunct to cheese milk at 104 cfu/ml did not completely suppress “wild” NSLAB populations, but it did appear to reduce nonstarter species and strain diversity in Colby and young Cheddar cheese. Nonetheless, nonstarter populations in all 6-mo-old cheeses were dominated by wild L. casei. Interestingly, the dominant strains of L. casei in each 6-mo-old cheese appeared to be affected more by adjunct treatment and not cheese variety.

Accumulation of Free L-Glutamic Acid in Full- and Reduced-fat Cheddar Cheese Ripened at Different Time/temperature Conditions

Influence of ripening conditions on accumulation of free L-glutamic acid (FGA) in full (FF)- and reduced-fat (RF) Cheddar cheese was investigated. Cheeses were ripened isothermally at 5 and 8°C for 6 months; aged at 5 and 8°C for 1 and 2 months and then at 8 and 5°C, respectively, for 5 and 4 months, respectively; or aged for 1 and 2 months at the latter temperatures and then again at 5 or 8°C for 4 and 3 months, respectively. In all cases, accumulation of FGA correlated well with accumulation of soluble nitrogen-containing fractions of cheese and, for isothermally aged cheeses, was linearly related to cheese age. Results suggested that level of FGA might be considered a ripening index in both FF and RF Cheddar. Level of FGA in cheese ripened at 8°C was significantly higher than that in cheese ripened at 5°C and, at a given aging conditions, level of FGA in FF cheese was significantly lower than that in RF cheeses. Increasing or decreasing aging temperature by 3°C at different cheese ages resulted in cheese-specific FGA levels that differed significantly from those obtained with cheeses ripened isothermally at 8°C or 5°C. Accumulation of FGA was influenced by effects of aging conditions and cheese composition on cheese-age-specific proteolytic activities in cheese. Results suggested that small changes in aging temperature, at desired stages during aging, may offer opportunities in controlling and modulating rate and extent of proteolytic activities during cheese aging and thus provide tools to better modulate the development of cheese quality attributes.