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

Abstract

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.