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 1,000mg/kg) and submitted to physicochemical and microbiological analysis at 1, 15, and 30d of refrigerated storage. Higher concentrations of glucose oxidase (750 and 1,000mg/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.
Speciation, the evolution of reproductive isolation among populations, is continuous, complex, and involves multiple, interacting barriers. Until it is complete, the effects of this process vary ...along the genome and can lead to a heterogeneous genomic landscape with peaks and troughs of differentiation and divergence. When gene flow occurs during speciation, barriers restricting gene flow locally in the genome lead to patterns of heterogeneity. However, genomic heterogeneity can also be produced or modified by variation in factors such as background selection and selective sweeps, recombination and mutation rate variation, and heterogeneous gene density. Extracting the effects of gene flow, divergent selection and reproductive isolation from such modifying factors presents a major challenge to speciation genomics. We argue one of the principal aims of the field is to identify the barrier loci involved in limiting gene flow. We first summarize the expected signatures of selection at barrier loci, at the genomic regions linked to them and across the entire genome. We then discuss the modifying factors that complicate the interpretation of the observed genomic landscape. Finally, we end with a road map for future speciation research: a proposal for how to account for these modifying factors and to progress towards understanding the nature of barrier loci. Despite the difficulties of interpreting empirical data, we argue that the availability of promising technical and analytical methods will shed further light on the important roles that gene flow and divergent selection have in shaping the genomic landscape of speciation.
The performance of check-all-that-apply (CATA), projective mapping, sorting and intensity scales was assessed for determining consumer perception of probiotic yogurts, two prototypes added with ...glucose oxidase, a potential oxygen scavenger and 04 commercial brands available in the Brazilian market. Each sensory methodology was tested by administrating the tests to 30 regular consumers of the product. Napping and CATA did not provide adequate discrimination of the samples while better results were noted for sorting and intensity scales, separating the yogurts containing glucose oxidase from the commercial probiotic yogurt. Sensory methodologies using consumer responses present potential options for the characterization of food matrices with multiple sensory sensations, such as probiotic yogurt.
•CATA, sorting, napping and intensity scales to characterize probiotic yogurts•Sorting and intensity scales presented similar results.•Prototype yogurts presented red points, acid taste, bitter taste and viscous.
The stability of probiotic yogurts added with glucose oxidase and packaged in different plastic packaging systems that present different oxygen permeability transfer rates (0.09, 0.2, 0.39 and ...0.75mLO2/day) was evaluated during 28days of refrigerated storage. Probiotic stirred yogurts were submitted to physicochemical (pH, proteolytic activity, dissolved oxygen) and microbiological analyses (yogurt bacteria, Lactobacillus acidophilus and Bifidobacterium longum) as well as the content of organic acids (lactic and acetic acid) and aroma compound (diacetyl and acetaldehyde) were assessed. Overall, yogurts packaged in plastic containers with lower oxygen permeability rates showed a higher extent of post-acidification, proteolysis and organic acid production. Additionally, these samples also presented a lower content of dissolved oxygen and a lower decrease of the probiotic bacteria count. No influence on the production of aroma compounds was observed. Our results suggest that the use of packaging systems with different oxygen permeability rates coupled with the addition of glucose oxidase presented an interesting technological option to minimize the oxidative stress in probiotic yogurts.
► Probiotic yogurts with glucose oxidase packaged in plastic materials. ► Post-acidification, proteolysis and organic acids production improved. ► Probiotic bacteria counts and aroma compound with few alterations.
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.
► Yogurt manufactured with increased levels of oligofructose. ► Weak gel, showing thixotropy and pseudoplastic behavior was observed. ► Survival analysis methodology indicated addition of 2.58% ...wt.v−1 of oligofructose.
The addition of prebiotics such as oligofructose to yogurt can result in a product with consumer benefits, since they stimulate growth of benefic bacteria present in the intestine and also provide a low calorie product, since one can add less sugar to the formulation due to their sweetening power. This work aimed to evaluate the effect of increasing concentrations of oligofructose addition on physicochemical, rheological and microbiological characteristics of non-flavored yogurt. Furthermore, it was investigated the reaction of consumers with the use of the survival analysis methodology. The addition of oligofructose showed no influence on the pH, proteolysis or the viability of Streptococcus thermophilus or Lactobacillus bulgaricus during 28days of refrigerated storage (p>0.05). According to rheological measurements the yogurt supplemented with oligofructose was characterized as a weak gel, showing thixotropic and pseudoplastic behavior. Survival analysis was used to investigate consumer responses with respect to different levels of supplementation of plain yogurt with oligofructose (0%, 2%, 4%, 6% and 8% wt.v−1). Using the survival analysis and considering a rejection by 25% of the consumers, the level of oligofructose that can be added to the yogurt was shown to be 2.58% wt.v−1.
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.
The wide prevalence of celiac disease and wheat allergy has led to a growing demand for gluten-free foods that present a suitable sensory acceptance. This research aimed to identify the drivers of ...liking of prebiotic gluten-free breads. A consumer test with 65 celiac people was performed. In addition, the sensory profiling was carried out by 15 trained assessors using quantitative descriptive analysis (QDA). By using QDA, the samples differed significantly in relation to all attributes, and partial least squares (PLS) regression was used to identify the drivers of liking of gluten-free breads. The results show that the most desired sensory properties of such products are apparent softness, traditional bread aroma, sweetness and crumb color. In this context, these attributes can be considered drivers of liking of prebiotic gluten-free breads and they should be taken into consideration by bakery processors at the development of new gluten-free products.
•Differences in formulation of gluten-free breads influenced the sensory perception.•Breads supplemented with raw sugar and FOS were most acceptable.•Sweet taste and crumb color were considered drivers of liking.
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.
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 0.8g/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.
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