Renato João Sossela de Freitas

Optimization of the production of aroma compounds by Kluyveromyces marxianus in solid-state fermentation using factorial design and response surface methodology.

Studies were carried out for the production of aroma compounds in solid-state fermentation using factorial design and response surface methodology (RSM) experiments. Five agro-industrial residues were evaluated as substrate for cultivating a strain of Kluyveromyces marxianus. The results proved the feasibility of using cassava bagasse and giant palm bran (Opuntia ficus indica) as substrates to produce fruity aroma compounds by the yeast culture. In order to test the influence of the process parameters on the culture to produce volatile compounds, two statistical experimental designs were performed. The parameters studied were initial substrate pH, addition of glucose, cultivation temperature, initial substrate moisture and inoculum size. Using a 2(5) factorial design, addition of glucose and initial pH of the substrate was found statistically significant for aroma compounds production on palm bran. Although this experimental design showed that addition of glucose did not have a significant role with cassava bagasse, 2(2) factorial design revealed that glucose addition was significant at higher concentrations. Head-space analysis of the culture by gas chromatography showed the production of nine and eleven compounds from palm bran and cassava bagasse, respectively, which included alcohols, esters and aldehyde. In both the cases, two compounds remained unidentified and ethyl acetate, ethanol and acetaldehyde were the major compounds produced. Esters produced were responsible for the fruity aroma in both the cases. With palm bran, ethanol was the compound produced in highest concentration, and with cassava bagasse (both supplemented with 10% glucose), ethyl acetate was produced at highest concentration, accumulating 418 and 1395µmoll(-1) head-spaceg(-1) substrate in 72h, respectively.

Aroma compounds produced by Kluyveromyces marxianus in solid state fermentation on a packed bed column bioreactor

Studies were carried out for the production of aroma compounds by Kluyveromyces marxianus grown on cassava bagasse in solid state fermentation using packed bed reactors, testing two different aeration rates. Respirometric analysis was used to follow the growth of the culture. Headspace analysis of the culture by gas chromatography showed the production of 11 compounds, out of which nine were identified. Ethyl acetate, ethanol and acetaldehyde were the major compounds produced. Lower aeration rate (0.06l h−1 g−1 of initial dry matter) increased total volatile (TV) production and the rate of production was also increased at this aeration rate. Using an aeration rate of 0.06l h−1 g−1 maximum TV concentrations were reached at 24 h and at 40 h with 0.12l h−1 g−1.

Segurança alimentar de hortaliças orgânicas: aspectos sanitários e nutricionais

The search for organic foods is expressive worldwide due to the population awareness about the health risks resulting from the presence of chemical residues in food. Several studies suggest that some practices of organic farming, such as the use of animal manure and rules prohibiting the use of conventional pesticides, can increase the microbiological and parasitic risks. Hence, these foods would not be suitable for human consumption. In this context, the present research aimed at determining the sanitary quality of organic vegetables through the evaluation of microbiological contamination by total and fecal and coliforms, Salmonella sp., and parasitological contamination. Moreover, samples of organic lettuce, carrots, and tomatoes from the Metropolitan Region of Curitiba, Parana, were submitted to physicochemical evaluation to assess their nutritional quality. Thermotolerant coliforms, or fecal coliforms, were detected in 40% of the lettuce and in 25% of the carrot samples. It was observed that 25% of the carrot and 20% of lettuce samples presented Salmonella sp., whereas the tomato samples did not present thermotolerant coliforms or Salmonella sp. The major parasites identified in the lettuce samples were acarus, Entamoeba sp., eggs of Ancylostoma sp., and insects. Entamoeba sp., eggs of Ancylostoma sp. and Toxocara sp. were identified in the organic carrot samples, while the tomato samples did not present any parasitological contamination. The data suggest that the organic lettuce and carrot samples might have been contaminated somehow by the soil, water, domestic animals, or non-suitable fertilizers.

Qualidade do tomate de mesa cultivado nos sistemas convencional e orgânico

The presence of organic products in the aisles of big supermarket chains indicates a market potential for these products. However, there is little technical and scientific information. Thus, the objective of this work was to determine the quality of tomatoes grown under conventional (CS) and organic (OS) systems, on sale in the metropolitan area of Curitiba, Brazil. Samples were evaluated in terms of mass, specific weight, ash, total solids, total soluble solids, total titratable acidity, total soluble solids/total titratable acidity ratio, pH, vitamin C, nitrates, nitrites, multiresidues. There were no significant differences between conventional and organic tomatoes, except in a 5 per cent difference in humidity, according to the Tukey test. Regarding the toxicological analyses, multiresidues and benzimidazole were not detected up to the limit of 0.04 mg.kg-1 and likewise carbendazim up to 0.1 mg.kg-1. Pesticide residues belonging to the dithiocarbamate chemical group were identified at levels of 0.01 mg.kg-1 in two samples of conventionally cultivated tomatoes. These levels are below the recommended upper limit for mancozebe fungicide (2.0 mg.kg-1 CS2).

Desenvolvimento de embutido fermentado por Lactobacillus probióticos: características de qualidade

Probiotic Lactobacillus strains have been widely used in dairy products. Recently, attention has been directed to the use of probiotics in meat products, mainly in fermented sausages. The effect of the utilization of Lactobacillus casei, L. paracasei and L. rhamnosus strains on physicalchemical, microbiological and sensory quality of fermented sausage was evaluated. The sausages were processed in four batches: one was used as the control, while the other three batches received one of the probiotic strains each. The manufacturing procedure described for Italian salami with 25 days of fermentation and ripening was followed. The presence of probiotic Lactobacillus resulted in a faster pH decrease, which affected the taste of the probiotic sausages. There was an increase in acid notes, mostly in the sausage containing L. rhamnosus. The lactobacilli strains also decreased the growth of Staphylococcus xylosus; however, they did not affect the number of Pediococcus pentosaceus and the acceptability of the sausages in the sensory evaluation. All Lactobacillus strains showed an increase in viable cell count during manufacturing and this parameter remained high until the end of ripening. The viability of the utilization of probiotic Lactobacillus, especially L. paracasei and L. casei, in fermented sausage, maintaining the quality characteristics of the product, was demonstrated.

Production and shelf-life studies of low cost beverage with soymilk, buffalo cheese whey and cow milk fermented by mixed cultures ofLactobacillus casei ssp.shirota andBi-fidobacterium adolescentis

A study was performed to develop a fermented milk beverage with the aim to increase the potential application of buffalo cheese whey and soymilk. A mixed substrate was prepared by selective combination, which contained buffalo cheese whey 35%, soymilk 30% and cow milk 35%. The substrate mixture was fermented by a mixed culture of Lactobacillus casei shirota and Bifidobacterium adolescentis at 37 °C for 8 h keeping a 1 : 1.5 proportion between the lactic and bifidobacteria within a 5% (v/v) inoculum size. The fermented beverage was lightly extra‐flavoured with vanilla essence and subjected to chemical, microbiological and sensory evaluations during storage for 28 days at 4 °C. Except a slight variation in the acidity, no other properties changed even after 28 days. There were no contaminating organisms (Salmonella and coliforms), which indicated the sanitary and hygienic conditions of the processing and the viable cells of the bacterial strains was well within recommended limits (6.8 × 108 cells for L. casei and 2.3 × 107 cells for Bifidobacterium). No negative changes were found in the sensory characteristics of the beverage allowing its good acceptability in all during the storage period.

Structural, physico-chemical, thermal and pasting properties of potato (Solanum tuberosum L.) flour

In this work, two varieties of potato flour (Ágata and IAPAR Cristina) were studied by simultaneous thermogravimetry–differential thermal analysis (TG–DTA), differential scanning calorimetry (DSC), rapid viscoamylographic analysis (RVA), and microscopy (NC-AFM) that were compared with conventional physico-chemical analysis, according different granulometry of each flour. Flours of IAPAR Cristina showed higher levels of starch, fiber, and phosphate and it showed higher thermal stability (TG–DTA), as well as higher pasting temperature and viscosity (RVA), and lower enthalpy of gelatinization (DSC) in the two granulometries. Flours of Agata showed higher gelatinization enthalpy (DSC) and lower pasting temperature (RVA). Atomic force microscopy—non contact method (NC-AFM), was important to check for protrusions and pores of the flour surfaces. The differences between cultivars can be attributed mainly to the genotypes and growth conditions of the tubers, which can modify the flour properties.

Qualidade pós-colheita do tomate de mesa convencional e orgânico

The objective of this work was to evaluate the postharvest quality of fruits grown using different systems. Conventional (CS) tomatoes of the variety Raisa and Organic (OS), variety Santa Clara rustic, were stored at 23.5 ± 2 oC, RH 74% ± 5 and analyzed for mass, specific weight, ash, total solids, total soluble solids, total titrable acidity, total soluble solids/total titrable acidity ratio, pH, vitamin C, Salmonella spp., total coliforms, faecal coliforms, molds and yeasts, and sensory analysis (using Quantitative Descriptive Analyses - QDA). The time of storage was of 13 days for the conventional tomatoes and 14 days for the organic tomatoes. Weight loss (3,74%) was lower for the conventional tomatoes. Both fruits were similar in the physical, chemical, sensory and microbiological analysis in the different maturity stages

Padrão de identidade e qualidade do tomate (Lycopersicon esculentum Mill.) de mesa

The commercial value of tomatoes (Lycopersicon esculentum Mill.), is defined by the fruit’s identity and quality characteristics, which can be evaluated by product classification. The present literature review had as objective to describe the identity and quality standards of tomatoes for fresh consumption, through the classification. The tomatoes for fresh consumption are classified in groups, subgroups, classes and types. According to the fruit’s shape, tomatoes are classified in two groups: oblong, when the longitudinal diameter is greater than the transversal diameter; and round, when the longitudinal diameter is smaller or equal to the transversal diameter. According to the fruit’s maturity, it is classified in five subgroups: mature green, breaker, pink, red and mature red. The class is determined by the greatest transversal diameter inside the same group. Oblong tomatoes are classified in three classes: big, medium and small. Round tomatoes are classified in four classes: giant, big, medium and small. According to the occurrence of serious damage and small defects on the fruit, it is classified in types, which can be extra, special or selected and commercial. The following are considered serious damage: decay, extreme maturity, burns, frost bites and rottenness at blossom end. Stains, hollowness, deformities, immaturity and little damages are considered small defects. The sample is classified as not meeting standards if it exceeds the requirements stated by the Department of Agriculture.

Stability studies and shelf life estimation of a soy-based dessert

This work is aimed at evaluating the physicochemical, physical, chromatic, microbiological, and sensorial stability of a non-dairy dessert elaborated with soy, guava juice, and oligofructose for 60 days at refrigerated storage as well as to estimate its shelf life time. The titrable acidity, pH, instrumental color, water activity, ascorbic acid, and physical stability were measured. Panelists (n = 50) from the campus community used a hedonic scale to assess the acceptance, purchase intent, creaminess, flavor, taste, acidity, color, and overall appearance of the dessert during 60 days. The data showed that the parameters differed significantly (p < 0.05) from the initial time, and they could be fitted in mathematical equations with coefficient of determination above 71%, aiming to consider them suitable for prediction purposes. Creaminess and acceptance did not differ statistically in the 60-day period; taste, flavor, and acidity kept a suitable hedonic score during storage. Notwithstanding, the sample showed good physical stability against gravity and presented more than 15% of the Brazilian Daily Recommended Value of copper, iron, and ascorbic acid. The product shelf life estimation found was 79 days considering the overall acceptance, acceptance index and purchase intent.