Efeito da alta pressão hidrostática sobre as propriedades físico químicas, microbiológicas e sensoriais de queijo Minas Frescal com redução de sódio

Abstract

The aim of this study was to evaluate the effect of high hydrostatic pressure on physical, chemical, microbiological and sensory characteristics of Minas Frescal cheese produced with reduced sodium content. Initially a literature review was presented on the main techniques used to reduce the sodium content. After identifying the optimal salt concentration of Minas Frescal cheese it was studied the effect of information regarding the excessive salt intake on health towards the consumer preference by means of survival analysis and by the acceptance in structured 9-point hedonic scales. Subsequently it was evaluated the effect of salt concentration and the salting method on production yield, physicochemical composition (moisture, ash, protein, fat), titrable acidity, pH, minerals (sodium and calcium content) and sensory characteristics (hedonic test and check-all-that-apply (CATA) of “Minas Frescal” cheese. For both the experimental design involved the factorial combination of varying concentrations of sodium chloride (0.2, 1.6 and 3.0%) and salting method (salting and sant in the milk mass). Finally it was investigated the combined effect of pressurizing at different pressures (300, 400 and 500MPa / 5 min) and salt content (40, 70 and 100% NaCl) where 100% of NaCl is equivalent to 1.6% of NaCl content/volume of milk (this content set out in Chapter 3) on the physic-chemical, microbiological and sensorial characteristics (perception of salty taste) of Minas Frescal cheese, by using a complete factorial experimental design 2^2 with triplicate at the midpoint. From the data collected parametric models were obtained allowing the estimation of the optimum salt concentration: 3.2 +/- 0.4 (%NaCl). For the cheese with such salt concentration it was obtained 21.5% of consumer rejection, of which 8.3% for considering the Minas Frescal cheese of being "little salty" and 13.2% for considering it “too salty”. Information on the health hazards due to excessive sodium intake was not significant (p>0.05) for the consumers. Either the effect of salt concentration and/or method of salting either individually or their interaction resulted in significant differences for the parameters moisture, ash, protein and minerals (p<0.05). The salt concentration showed the highest influence on the response variables evaluated in this study. The yield statistically varied among the treatments (p<0.05), and was influenced by the level of sodium, while calcium concentration and also the yield were affected by the salting method, salt concentration and interaction of the parameters (p<0.05). The yield values for different treatments were statistically different (p<0.05). With respect to the sensory analysis the salting methods influenced the acceptance only for the cheeses elaborated with 3.0% NaCl (p<0.05). Salt concentration (1.6%) for both salting methods achieved the highest average acceptance. Significant differences for the physical and chemical microbiological and sensory parameters (p < 0.05) were observed. The physical-chemical response variables more influenced by the treatments were: sodium content, calcium content, NaCl content, salt content, moisture, DPPH, proteolysis and antihypertensive activity. Higher levels of pressure and salt content resulted in further reduction in the microbial population. Bioactive properties (antihypertensive activity and antioxidant activity) of the Minas Frescal cheese was confirmed by the analyses. Regarding the sensory analysis no increase in the perception of salty taste occurred due to the high pressure treatments evaluated.