Effect of inoculating Lactococcus lactis subsp. cremoris T1 on physical and functional characteristics of reduced-fat cheese
Date Issued
2012
Date
2012
Author(s)
Kuo, Pei-Chuan
Abstract
Cheese is a good source of protein and calcium, but it is a major source of saturated fat. Demand for cheese with less fat is growing. The reduced-fat cheeses are usually characterized as having poor body, flavor and functional properties because of high moisture. Addition of the fat replacers may provide the solution. Exopolysaccharide (EPS) could increase water-holding capacity and interfere with protein-protein interactions in food products, which are important properties required in fat replacement. Lactococcus lactis subsp. cremoris T1 (T1), isolated from Taiwanese ropy fermented milk, may act as a fat replacer in reduced-fat cheese manufacture according to its EPS-producing property. Thus, the purpose of this study was to investigate of effect of inoculating Lactococcus lactis subsp. cremoris T1 on physical and functional characteristics of reduced-fat cheese.
First, the growth medium, which was proportion of whey powder, yeast extract, citrate and potassium phosphate, was optimized using response surface methodology (RSM) to first construct a surface model, with sequential quadratic programming (SQP) subsequently adopted to optimize the model and evaluate the cell counts of T1. Optimization results indicated that after 30 sets of randomly generated initial points leading to optimal cell counts (local optimal) ranging from 7.00 to 9.00 log CFU/mL, the global optimal cell count of T1 was found to be 9.00log CFU/mL (99.99% certainty). The verification experiment yielded a result close to the predicted values, with no significant difference (P > 0.05).
After maximizing the T1 growth medium, we produced reduced-fat Mozzarella cheese in an industrial cheese factory. The full fat cheese and reduced-fat cheese were positive and negative controls, respectively. Results indicated that addition of T1 could enhance moisture content and improve cheese texture. The customer preferential score of the reduced-fat cheese sample showed no difference in appearance, flavour and aroma with the full-fat counterpart.
Additionally, the functional characteristics including the immunoregulatory and anti-colitis effects of T1 reduced-fat cheese were also evaluated in this study. For immunoregulatory effect, the T1 samples could stimulate the production of TNF-α, IL-10, IL-1β and IL-6 in murine macrophage cell line RAW 264.7. For anti-colitis effect, the T1 samples could also strengthen the epithelial barrier function in vitro by increasing the transepithelial electrical resistance（TEER）but not significantly upregulated the level of the chemokine CCL-20 at both the apical and basolateral sites of Caco-2 cell monolayer.
In conclusion, this study demonstrated that the reduced-fat cheese made with T1 shows no significant difference in chemical properties, textural characteristics when compared with the full fat cheese control. The T1 cheese also demonstrated the immunoregulatory and anti-colitis effects. These findings will help develop new healthy cheese products.
Subjects
Exopolysaccharide
Lactococcus lactis subsp. cremoris T1
Immunoregulatory
Reduced-fat cheese
Type
thesis
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