The effect of transglutaminase on the properties of milk gels and processed cheese

The aim of this study was to investigate the influence of transglutaminase (TG) on rennet coagulation properties, and the impact on the properties of processed cheese. The TG was added before, at the same time as, and after the addition of rennet. The parameters moisture, total solids and proteins and physical parameters (syneresis index, wheying‐off and rheological behaviour) were measured. The manufacturing of the milk gels treated with transglutaminase after rennet addition was shown to be an effective means of improving the physical properties (reduced synereseis index and increased consistency index) of processed cheese, possible by the occurrence of enzymatic cross‐linking.     

Influence of transmembrane pressure on the separation of caprine milk oligosaccharides from protein by cross‐flow ultrafiltration

Goat milk shows similarities with human milk in terms of their oligosaccharides composition. However, the supplementation of goat milk protein in infant formulae is not allowed, which demands a previous separation of oligosaccharides from protein. The purpose of this study was to evaluate the effect of transmembrane pressure on the fractionation of oligosaccharides, protein, lactose and calcium in the diafiltration of caprine milk through a 50 kDa tubular ceramic membrane. Permeates with more than 99% of the original oligosaccharides were obtained after four diavolumes. It was seen that transmembrane pressure had a great influence on filtration time and protein transmission.     

MICROBIAL STABILIZATION OF INTERMEDIATE MOISTURE FOOD SURFACES III. EFFECTS OF SURFACE PRESERVATIVE CONCENTRATION AND SURFACE pH CONTROL ON MICROBIAL STABILITY OF AN INTERMEDIATE MOISTURE CHEESE ANALOG

Localized surface condensations affect microbial stability of intermediate moisture foods (IMF). Two surface modifications previously reported were tested for their ability to improve microbial surface stability; control of surface preservative concentration and reduced surface pH.
The effectiveness of a high surface sorbic acid concentration controlled by a zein coating was confirmed in Staphylococcus aureus S-6 surface challenge experiments under extreme testing conditions. Samples with bulk water activity (aw) of 0.88, stored at 30°C under constant 88% relative humidity (RH) remained stable for over 16 days. Uncoated controls were stable for only 2 days. Samples with bulk aw = 0.85, exposed to cycles of 12 h at85% RH and 12h at 88% RH, remained stable for more than 28 days. Uncoated controls were stable for only 3 days.
The reduced surface pH approach to microbial stability required the formulation of an IMF model with low total electrolyte concentration which was coated with a deionized mixture of λ-carrageenan and agarose. The effectiveness of the resulting 2.5 fold increase in the surface availability of the active form of sorbic acid as compared to food bulk was confirmed in a challenge test with S. aureus S-6. In a test with samples at aw = 0.88, stored at RH = 88% and 30°C, we found a stability period of about 20 days and it seems possible to increase it.