Effect of incorporation of antioxidants on the chemical, rheological, and sensory properties of probiotic petit suisse cheese.

This work investigated the effect of the addition of different antioxidants (ascorbic acid, glucose oxidase, cysteine, and jabuticaba extract) on the rheological and sensorial properties of the probiotic petit suisse cheese. Absence of influence of the antioxidants at the physico-chemical characteristics of the petit suisse cheese was observed. Overall, the petit suisse cheeses presented weak gel characteristics and behaved as pseudoplastic material, except for control. All treatments exhibited a thixotropic non-Newtonian behavior; however, higher hysteresis area was obtained for control sample, which indicates that antioxidants incorporated to petit suisse had a protective effect on the typical thixotropic behavior of the Quark gel. The commercial sample presented higher scores for all aspects by consumers, whereas the probiotic petit suisse samples presented opposite behavior. Projective mapping was able to generate a vocabulary where the sample containing jabuticaba skin extract obtained by supercritical extraction was characterized by the panelists as presenting grape flavor and purple color.

The influence of sweeteners in probiotic Petit Suisse cheese in concentrations equivalent to that of sucrose.

As in the case of probiotic functional foods in recent years, demand has increased notably for light or diet foods with added sweeteners. However, little is known about the effect of different sweeteners on the microorganisms present. Thus, the objective of the current study was to establish the ideal sucrose concentration and equivalent concentrations of different sweeteners and to determine, by microbiological analyses, the influence of these compounds on the viability of the starter and probiotic cultures used in the production of strawberry-flavored Petit Suisse cheese during its shelf life. The ideal sucrose concentration was determined using the just-about-right (JAR) scale, and the equivalent concentrations of the sweeteners were subsequently determined by the magnitude estimation method. Microbiological analyses were also carried out to check the viability of the cultures during the product's shelf life. The results showed that the compounds Neotame (NutraSweet, Chicago, IL) and stevia presented, respectively, the greatest and least sweetening power of the sweeteners tested. None of the sweeteners used in this study exerted a negative effect on the viability of the starter or probiotic cultures, and thus we were able to obtain a probiotic, functional food with reduced calorie content.

Development of probiotic dairy beverages: rheological properties and application of mathematical models in sensory evaluation.

Strawberry-flavored probiotic dairy beverages (2% vol/vol Lactobacillus acidophilus) were produced using 0, 20, 35, 50, 65, and 80% (vol/vol) whey in their formulations. Mathematical models (survival analysis, minimal significant difference, and mean global acceptance) were used to identify the optimal (sensorially) whey concentration in probiotic beverages. Fifty-five consumers evaluated acceptance of the beverages using hybrid 9-point hedonic scales. In addition, Lb. acidophilus were enumerated and pH was determined. Rheological behavior is an important characteristic for the processing and sensory acceptance of dairy beverages, varying with the presence of additives, fermentation process (time, bacterial strain), and whey concentrations used. All beverages presented minimal counts of 8 log cfu/mL of Lb. acidophilus, and pH ranged from 4.09 to 4.14. Increasing the whey content increased the fragility of the gel structure, probably because of the replacement of casein by whey proteins, once the concentrations of other ingredients in formulation were fixed. Whey content had a significant effect on acceptance of the probiotic dairy beverages; beverages with whey contents greater than 65% resulted in lower acceptance by consumers. The model of mean global acceptance presented 2 solutions with high sensory scores: beverages with 12 and 65% whey, the latter being of interest because it allows greater use of the whey by-product. The Weibull distribution presented a prediction of whey concentration of 49%, with higher sensory acceptance. The methodologies used in this research were shown to be useful in determining the constituents of food formulations, especially for whey-based probiotic beverages.

Short communication: Effects of different whey concentrations on physicochemical characteristics and viable counts of starter bacteria in dairy beverage supplemented with probiotics.

Fermented dairy beverages supplemented with the probiotics Lactobacillus acidophilus and Bifidobacterium lactis containing different concentrations of whey in their formulas (0, 20, 35, 50, 65, and 80%, vol/vol) were processed and checked for pH; proteolysis; levels of glucose, lactose, ethanol, acetic acid, lactic acid, diacetyl, and acetaldehyde; and lactic bacteria and probiotic counts. The results allowed the effect of whey concentration on the dairy beverages to be observed for each of the different parameters analyzed. The degree to which the whey concentration was useful for the microbial cultures, particularly probiotic cultures, appeared to have a limit. In general, dairy beverages processed with different levels of whey in their formulation exhibited good potential as a food matrix for supplementation with probiotic bacteria, with production of characteristic compounds of fermented milk products, such as volatiles and organic acids.

Reduced fat and sugar vanilla ice creams: sensory profiling and external preference mapping.

The aims of this study were (1) to map sensory attributes of vanilla ice cream with reduced fat and sugar, and (2) to determine drivers of liking by applying external preference mapping and reveal the relationship between descriptive attributes and hedonic judgments using the partial least squares method. Descriptive sensory profiles (n=11) and consumer test (n=117) of 6 samples of vanilla ice cream (3 traditional and 3 with reduced fat and sugar) were determined. The attributes brightness and sweet aftertaste for sample and creaminess (appearance and texture) and sweet aroma contributed positively to the acceptance of ice cream samples. The attributes aeration, powdered milk aroma and flavor, and white chocolate aroma and flavor contributed positively to the acceptance of the ice creams. The attributes hydrogenated fat aroma and flavor were responsible for the lower acceptance of samples. The reduction in fat and sugar did not necessarily cause a decrease in acceptance. The most important factors were selection of the appropriate sweetener system and the use of good quality raw material.

Effect of addition of CO2 to raw milk on quality of UHT-treated milk.

The objective of this study was to evaluate the effect of addition of CO(2) to raw milk on UHT milk quality during storage. Control milk (without CO(2) addition) and treated milk (with CO(2) addition up to pH 6.2) were stored in bulk tanks at 4°C for 6d. After storage, both samples were UHT processed using indirect heating (140°C for 5s). Samples were aseptically packed in low-density polyethylene pouches and stored in the dark at room temperature. Raw milk was evaluated upon receipt for physicochemical composition, proteolysis, lipolysis, standard plate count, psychrotrophic bacteria, and Pseudomonas spp. counts, and after 6d of storage for proteolysis, lipolysis, and microbial counts. After processing, UHT milk samples were evaluated for physicochemical composition, proteolysis, and lipolysis. Samples were evaluated for proteolysis and lipolysis twice a month until 120d. Peptides from pH 4.6-soluble N filtrates were performed by reversed-phase HPLC after 1 and 120d of storage. A split-plot design was used and the complete experiment was carried out in triplicate. The results were evaluated by ANOVA and Tukey's test. After 6d of storage, CO(2)-treated raw milk kept its physicochemical and microbiological quality, whereas the untreated milk showed significant quality losses. A significant increase in proteolysis occurred during 120d of storage in both treatments, but the increase occurred 1.4 times faster in untreated UHT milk than in CO(2)-treated UHT milk. In both UHT milks, the proteolysis was a consequence of the action of plasmin and microbial proteases. However, the untreated UHT milk showed higher microbial protease activity than the treated UHT milk. The addition of CO(2) to the raw milk maintained the quality during storage, resulting in UHT milk with less proteolysis and possibly longer shelf life, which is usually limited by age gelation of UHT milk.

Probiotic cheese attenuates exercise-induced immune suppression in Wistar rats.

Intense physical activity results in a substantial volume of stress and hence a significant probability of immunosuppression in athletes, with milk proteins being, perhaps, the most recommended protein supplements. Consumption of a probiotic cheese can attenuate immune suppression induced by exhausting exercise in rats. A popular Brazilian fresh cheese (Minas Frescal cheese) containing Lactobacillus acidophilus LA14 and Bifidobacterium longum BL05 was fed for 2wk to adult Wistar rats, which then were brought to exhaustion on the treadmill. Two hours after exhaustion, the rats were killed and material was collected for the determination of serum uric acid, total and high-density lipoprotein cholesterol fraction, total protein, triacylglycerols, aspartate aminotransferase, alanine aminotransferase, creatine kinase, and blood cell (monocyte, lymphocyte, neutrophil, and leukocyte) counts. Exercise was efficient in reducing lymphocyte counts, irrespective of the type of ingested cheese, but the decrease in the group fed the probiotic cheese was 22% compared with 48% in the animals fed regular cheese. Monocyte counts were unaltered in the rats fed probiotic cheese compared with a significant decrease in the rats fed the regular cheese. Most importantly, ingestion of the probiotic cheese resulted in a >100% increase in serum high-density lipoprotein cholesterol and a 50% decrease in triacylglycerols. We conclude that probiotic Minas Frescal cheese may be a viable alternative to enhance the immune system and could be used to prevent infections, particularly those related to the physical overexertion of athletes.

Probiotic yogurts manufactured with increased glucose oxidase levels: postacidification, proteolytic patterns, survival of probiotic microorganisms, production of organic acid and aroma compounds.

We investigated the effect of increased glucose oxidase concentration as a technological option to decrease oxidative stress during the processing of probiotic yogurts. Probiotic yogurts were produced with increased concentrations of glucose oxidase (0, 250, 500, 750, or 1,000 mg/kg) and submitted to physicochemical and microbiological analysis at 1, 15, and 30 d of refrigerated storage. Higher concentrations of glucose oxidase (750 and 1,000 mg/kg) and a longer storage time were found to have an influence on the characteristics of the probiotic yogurt, contributing to more extensive postacidification, an increase in the dissolved oxygen level, and higher proteolysis. In addition, increased production of aroma compounds (diacetyl and acetaldehyde) and organic acids (mainly lactic acid) and a decrease in the probiotic bacteria count were reported. The use of glucose oxidase was a feasible option to minimize oxidative stress in probiotic yogurts. However, supplementation with excessive amounts of the enzyme may be ineffective, because insufficient substrate (glucose) is present for its action. Consumer tests should be performed to evaluate changes in the sensory attributes of the probiotic yogurts with increased supplementation of glucose oxidase. In addition, packaging systems with different permeability to oxygen should be evaluated.

Effect of the inoculation level of Lactobacillus acidophilus in probiotic cheese on the physicochemical features and sensory performance compared with commercial cheeses.

The complex metabolism of probiotic bacteria requires several technological options to guarantee the functionally of probiotic dairy foods during the shelf life. This research aimed to evaluate the effect of the supplementation of increasing amounts of Lactobacillus acidophilus (0, 0.4, or 0.8 g/L of milk) on the physicochemical parameters and sensory acceptance of Minas fresh cheese. In addition, the sensory acceptance of probiotic cheeses was assessed using a consumer test and compared with commercial cheeses (conventional and probiotic). High counts (9.11 to 9.42 log cfu/g) of L. acidophilus were observed throughout the shelf life, which contributed to the maintenance of its probiotic status and resulted in lower pH values and greater production of organic acids. The probiotic cheeses presented lower scores for appearance, aroma, and texture compared with conventional cheeses. Internal preference mapping explained almost 60% of the total variation of the data and showed a large number of consumers concentrated near the conventional cheeses, demonstrating greater preference for these samples. The findings indicated that some negative sensory effects could occur when high level of supplementation with L. acidophilus is used in probiotic cheese processing.

Manufacture of low-sodium Minas fresh cheese: effect of the partial replacement of sodium chloride with potassium chloride.

We investigated the effect of sodium reduction by partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on the manufacture of Minas fresh cheese during 21 d of refrigerated storage. Four treatments of low-sodium Minas fresh cheese were manufactured, with partial replacement of NaCl by KCl at 0, 25, 50, and 75% (wt/wt), respectively. The cheeses showed differences in the content of moisture, ash, protein, salt, and lipid contents, as well as on the extent of proteolysis and hardness throughout the storage period. However, no difference was observed among treatments within each storage day tested. The partial substitution of NaCl by KCl decreased up to 51.8% the sodium concentration of the cheeses produced. The consumer test indicated that it is possible to manufacture a low-sodium Minas fresh cheese that is acceptable to consumers by partial substitution of NaCl by KCl at 25% (wt/wt) in the salting step.

Processing optimization of probiotic yogurt containing glucose oxidase using response surface methodology.

Exposure to oxygen may induce a lack of functionality of probiotic dairy foods because the anaerobic metabolism of probiotic bacteria compromises during storage the maintenance of their viability to provide benefits to consumer health. Glucose oxidase can constitute a potential alternative to increase the survival of probiotic bacteria in yogurt because it consumes the oxygen permeating to the inside of the pot during storage, thus making it possible to avoid the use of chemical additives. This research aimed to optimize the processing of probiotic yogurt supplemented with glucose oxidase using response surface methodology and to determine the levels of glucose and glucose oxidase that minimize the concentration of dissolved oxygen and maximize the Bifidobacterium longum count by the desirability function. Response surface methodology mathematical models adequately described the process, with adjusted determination coefficients of 83% for the oxygen and 94% for the B. longum. Linear and quadratic effects of the glucose oxidase were reported for the oxygen model, whereas for the B. longum count model an influence of the glucose oxidase at the linear level was observed followed by the quadratic influence of glucose and quadratic effect of glucose oxidase. The desirability function indicated that 62.32 ppm of glucose oxidase and 4.35 ppm of glucose was the best combination of these components for optimization of probiotic yogurt processing. An additional validation experiment was performed and results showed acceptable error between the predicted and experimental results.

Monitoring the authenticity of low-fat yogurts by an artificial neural network.

The growing consumption of low- and reduced-fat dairy products demands routine control of their authenticity by health agencies. The usual analyses of fat in dairy products are very simple laboratory methods; however, they require manipulation and use of reagents of a corrosive nature, such as sulfuric acid, to break the chemical bounds between fat and proteins. Additionally, they generate chemical residues that require an appropriate destination. In this work, the use of an artificial neural network based on simple instrumental analyses, such as pH, color, and hardness (inputs) is proposed for the classification of commercial yogurts in the low- and reduced-fat categories (outputs). A total of 108 strawberry-flavored yogurts (48 probiotic low-fat, 36 low-fat, and 24 full-fat yogurts) belonging to several commercial brands and from different batches were used in this research. The statistical analysis showed different features for each yogurt category; thus, a database was built and a neural model was trained with the Levenberg-Marquardt algorithm by using the neural network toolbox of the software MATLAB 7.0.1. Validation with unseen data pairs showed that the proposed model was 100% efficient. Because the instrumental analyses do not require any sample preparation and do not produce any chemical residues, the proposed procedure is a fast and interesting approach to monitoring the authenticity of these products.

Sensory stability of ultra-high temperature milk in polyethylene bottle.

The objective of this study was to evaluate the sensory stability of ultra-high temperature (UHT) milk subjected to different heat treatments and stored at room temperature in white high density polyethylene bottles (HDPE) pigmented with titanium dioxide. Two lots of 300 units each were processed, respectively, at 135 and 141 degrees C/10 s using indirect heating and subsequently aseptically filled in an ISO class 7 clean room. These experimental lots were evaluated for appearance, aroma, flavor, and overall appreciation and compared to samples of commercial UHT milk purchased from local commercial stores. The time-temperature combinations investigated did not affect either the acceptability or the shelf life of the milk. Despite the limited light barrier properties of HDPE bottles, the product contained in the package tested exhibited good stability, with a shelf life ranging from 4 to 11 wk. Within this time period, the acceptability of the experimental lots was similar to that of the commercial products. The results achieved in this study contribute to turn the low-cost UHT system investigated into a technically viable option for small-size dairy processing plants.