Process variables in the osmotic dehydration of sliced peaches

This paper evaluated the influence of temperature and concentration of the sucrose syrup on the pre-osmotic dehydration of peaches. Physical (colour and texture) and chemical variables (soluble solid content; total sugar, reducing and non-reducing sugar contents; and titratable acidity) were investigated, as well as the osmotic dehydration parameters (loss of weight and water; solids incorporation). An experimental central composite design was employed varying the temperature (from 30 to 50 ºC) and concentration (from 45 to 65 ºBrix) and maintaining the syrup to fruit ratio (4:1), process time (4 hours), and format (slices). The degree of acceptance was used in the sensory analysis evaluating the following characteristics: appearance, taste, texture, colour, and overall quality using a hedonic scale. The results were modelled using the Statistica program (v. 6.0) and the Response Surface Methodology. The mathematical models of the following dimensionless variations yielded significant (p < 0.05) and predictive results: soluble solids content, total and non-reducing sugar contents, titratable acidity, colour parameter L*, and water loss. The models of the attributes colour and appearance yielded significant (p < 0.10) but not predictive results. Temperature was the prevalent effect in the models. The process conditions in the range from 50 to 54.1 ºC and from 45 to 65 ºBrix led to greater water losses and better sensory performances.

Changes in guava (Psidium guajava L. var. Paluma) nectar volatile compounds concentration due to thermal processing and storage

Guava nectars were formulated for approximately 10, 12, or 14 ºBrix, with 40% guava pulp. Sodium benzoate, 500 mg.kg-1 was used as preservative. The Brix value was adjusted with saturated sucrose syrup. The guava nectar was pasteurized (85 ºC/42 seconds) in tubular heat exchanger and then hot filled in 500 mL white glass bottles. The products were stored either at room temperature (25 ± 5 ºC) or refrigerated (5 ± 2 ºC) under fluorescent light exposure and analyzed on the day after processing (time zero) and also 40, 80, and 120 days of storage. Eight compounds were identified and quantified by Gas Chromatography (GC) -Mass Spectrometry (MS): hexanal, (E)-hex-2-enal, 1-hexenol, (Z)-hex-3-enol, (Z)-hex-3-enyl acetate, phenyl-3-propyl acetate, cinnamyl acetate, and acetic acid. There was no significant effect of thermal treatment on the volatile compound concentrations, except for a significant decrease (p = 0.0001) in hexanal and (Z)-hex-3-enyl acetate (p = 0.0029). As for the storage time, there was a much greater decrease in the esters contents, such as (Z)-hex-3-enyl and phenyl-3-propyl acetates. Cinnamyl acetate had the greatest decrease over storage time. Refrigeration was better than room temperature for guava nectar volatile compounds stability over storage time, mainly for esters compounds, which are important for the product aroma and flavor

Quality of Canned mandarin as affected by preservation liquid

This study is integrated within a research line dedicated to evaluate different options to introduce mandarin in Spanish agro-food industries and in both national and international markets. The effects of different preservation liquids (sucrose solution, sucrose and ascorbic acid solution, grape, and grapefruit juices), soluble solids (10, 12, 14 ºBrix), and thermal processing (30 seconds at 98 ºC) on vitamin C, color, carotenoids and sensory quality of canned Satsuma mandarin segments were studied. The liquid preservation that presented the best results was grapefruit juice, which provided the highest vitamin C (323 mg.L-1) and total carotenoids (16.4 mg.L-1) contents (the main carotenoid found was β-cryptoxanthin), intense orange color, high thermal stability, and very good sensory quality (e.g. intense floral and fresh-mandarin aromas and low levels of off-flavors).

Effect of different sweetener blends and fat types on ice cream properties

The development of processed foods requires the understanding of the phenomena that dictate the ingredient interactions normally used in food formulations, as well as the effects of the numerous operations involved in the processing of the final product. In ice creams, sugars are responsible for taste, but they also affect the freezing behavior and viscosity of processed mixes. Components such as fats influence mechanical properties, melting resistance, and palatability of final products. The objective was to study the technological effects of different sugars and fats on the structure of ice cream formulations. Fructose syrup was used as a substitute for glucose syrup in blends with sucrose, and palm fat was employed as an alternative to hydrogenated vegetable fat. The analysis of variance showed significant differences in chemical compositions. Hygroscopicity of fructose syrup increased the solids content in the formulations. Melting rate and overrun were higher in products added with this sugar. Palm fat caused changes in melting ranges of formulations, and higher melting rate was observed in the combination of palm fat and fructose syrup.

Production of isomaltulose obtained by Erwinia sp. cells submitted to different treatments and immobilized in calcium alginate

In recent decades, there has been an increase in the studies of isomaltulose obtainment, due to its physicochemical properties and physiological health benefits. These properties, which include low cariogenicity, low glycemic index and greater stability, allow the use of this sweetener as a substitute for sucrose in foods; besides the fact that it can be converted to isomalt, a dietary non-cariogenic sugar alcohol used in pharmaceuticals as well as in the food industry. Isomaltulose (6-O-α-D-glucopyronosyl-1-6-D-fructofuranose) is a disaccharide reducer obtained by the enzymatic conversion of sucrose - the α-glucosyltransferase enzyme. Different treatments were performed for the preparation of whole cells; lysed cells; and crude enzyme extract of Erwinia sp. D12 strain immobilized in calcium alginate. The packed bed column of granules, containing Erwinia sp. cells sonicated and immobilized in calcium alginate (CSI), reached a maximum conversion of 53-59% sucrose into isomaltulose and it presented activity for 480 hours. The converted syrup was purified and the isomaltulose crystallization was performed through the lowering of temperature. The isomaltulose crystals presented purity of 96.5%.

Evaluation of antioxidants stability by thermal analysis and its protective effect in heated edible vegetable oil

In this work, through the use of thermal analysis techniques, the thermal stabilities of some antioxidants were investigated, in order to evaluate their resistance to thermal oxidation in oils, by heating canola vegetable oil, and to suggest that antioxidants would be more appropriate to increase the resistance of vegetable oils in the thermal degradation process in frying. The techniques used were: Thermal Gravimetric (TG) and Differential Scanning Calorimetry (DSC) analyses, as well as an allusion to a possible protective action of the vegetable oils, based on the thermal oxidation of canola vegetable oil in the laboratory under constant heating at 180 ºC/8 hours for 10 days. The studied antioxidants were: ascorbic acid, sorbic acid, citric acid, sodium erythorbate, BHT (3,5-di-tert-butyl-4-hydroxytoluene), BHA (2, 3-tert-butyl-4-methoxyphenol), TBHQ (tertiary butyl hydroquinone), PG (propyl gallate) - described as antioxidants by ANVISA and the FDA; and also the phytic acid antioxidant and the SAIB (sucrose acetate isobutyrate) additive, which is used in the food industry, in order to test its behavior as an antioxidant in vegetable oil. The following antioxidants: citric acid, sodium erythorbate, BHA, BHT, TBHQ and sorbic acid decompose at temperatures below 180 ºC, and therefore, have little protective action in vegetable oils undergoing frying processes. The antioxidants below: phytic acid, ascorbic acid and PG, are the most resistant and begin their decomposition processes at temperatures between 180 and 200 ºC. The thermal analytical techniques have also shown that the SAIB antioxidant is the most resistant to oxidative action, and it can be a useful choice in the thermal decomposition prevention of edible oils, improving stability regarding oxidative processes.

Nutritional value of organic acid lime juice (Citrus latifolia T.), cv. Tahiti

Acid lime can be used as fresh fruit or as juice to increase the flavor of drinks. Therefore, it is necessary to analyze organic acid lime nutritional composition in order to evaluate if there are important differences among those conventionally produced. No significant differences in total titrable acidity, pH, ascorbic acid, sucrose, calcium, and zinc were found between the acid lime juice from organic biodynamic crops and conventional crops. However, the organic biodynamic fruits presented higher peel percentage than the conventional ones leading to lower juice yield. On the other hand, fructose, glucose, total soluble solids contents, potassium, manganese, iron, and copper were higher in the conventional samples. These results indicated few nutritional differences between organic and conventional acid lime juices in some constituents. Nevertheless, fruit juice from biodynamic crops could be a good choice since it is free from pesticides and other agents that cause problems to human health maintaining the levels similar to those of important nutritional compounds.

Study of the shelf-life of a mixed araça (Psidium guineensis Sw.) and marolo (Annona crassiflora Mart.) jam

The objective of this study was to add value to araça and marolo fruits by developing jams and verifying changes in their physical, chemical, and microbiological parameters during storage. The analyses were carried out every 2 months. From the results, it was shown that the levels of moisture (35.89 - 26.34%), lipids (0.43 - 0.27%), sucrose (30.62 - 28.98%), total pectin (0.83 - 0.50%), soluble pectin (0.52 - 0.38%), total phenolic compounds (180.31 - 135.52 mg.GAE 100 g-1), and organic acids (401.1 - 68.5 µg.g-1 citric acid) decreased during storage. However, the levels of protein (0.83 - 0.95%), carbohydrate (62.52 - 72.5%, calories (257,11 - 295,931 kcal), fiber (0.72 - 1.4%), total soluble sugar (62.52 - 70.44%), reducing sugar (32.05 - 41.41%), soluble solids (68.4 - 72.18 °Brix), consistency (0.33 - 0.44 N), total antioxidant potential (11.3 - 22.63%), and color (a* 7.56 - 9.49, and b* 8.63 - 10.49) increased during 1-year storage. The quality of the fruit jams studied was in accordance with the microbiological standards established by the Brazilian legislation. It was concluded that the mixed araça and marolo jam can be stored for 1 year without the addition of additives.

Effect of harvest at different times of day on the physical and chemical characteristics of vegetable-type soybean

The objective of this study was to evaluate the effect of harvest at different times of day on the chemical and physical characteristics of vegetable-type soybean BRS 267 cultivar, harvested at the R6 stage (seed development) and to compare it with that on the grains harvested at the R8 stage (maturation). The pods of the BRS 267 cultivar were harvested at the R6 stage (at 8:00 AM, 12:00 AM, and 6:00 PM), the color parameters were evaluated, and the grains were analyzed for chemical composition, activity inhibitor trypsin, phytic acid content, starch, sugars, fatty acids, and isoflavones. No differences were observed among the different harvest times in terms of the chemical constituents of vegetable-type soybean BRS 267 cultivar harvested at the R6 stage. Isoflavones content did not change with different harvest times, and the aglycone forms (daidzein, glycitein, and genistein) were found in smaller quantities at the R6 stage compared to the R8 stage. The color of the pods of soybean BRS 267 cultivar, harvested at the R6 stage did not change with different harvest times. The grains harvested at the R6 stage had lower protein content, phytic acid, and sucrose and higher levels of lipids, carbohydrates, starch, glucose, fructose, stachyose, and linolenic acids than those collected at the R8 stage. The different times of harvest did not affect the quality of the vegetable-type soybean BRS 267 cultivar harvested at stage R6. Nevertheless, it is recommended to harvest in the morning, when the temperature is milder, like other vegetables, to facilitate and optimize its marketing and in natura consumption.

Physicochemical and microbiological characterization of cassava flower honey samples produced by africanized honeybees

Cassava producers in the region of Marília-São Paulo are integrating their farming activity with beekeeping to diversify their income. The aim of this study was to evaluate the physicochemical and microbiological quality of honey samples produced by Africanized honeybees Apis mellifera from cassava flower in 2008. Analysis were carried out for pH, total soluble solids (TSS), acidity, moisture, reducing and total sugars, apparent sucrose, hydroxymethylfurfural, color, ash, proteins, water insoluble solids, diastasic activity, mineral content, microbiological evaluations, and mineral and hydrocyanic acid (HCN) content. The honey samples showed physicochemical and microbiological characteristics favorable to commercialization, with the exception of apparent sucrose and acidity, which show the need for a narrow focus of attention to the honey maturation degree at the harvest time and more careful monitoring during production and processing. The commercialization of Brazilian cassava honey, still little explored, can be widely spread in the market since the levels of hydrocyanic acid (HCN) showed no consumption risk; in addition the simultaneous production of honey and cassava provides an alternative to family income increase.

An alternative method for screening lactic acid bacteria for the production of exopolysaccharides with rapid confirmation

The accumulation of exopolysaccharides (EPS) produced by microorganisms occurs in the presence of excess substrate and limiting conditions of elements that are essential to growth, such as nitrogen, phosphorus, sulfur, and magnesium. The presence of EPS produced by bacterial cells contributes to slime colonies formation in solid medium and increased viscosity in liquid medium. This paper proposes an alternative method for screening EPS-producing lactic acid bacteria using solid medium-containing discs of filter paper that are saturated with active cultures. The screening was carried out under different culture conditions varying the type of sugar, pH, and temperature. EPS production was visualized by the presence of mucoid colonies on the discs, which was confirmed by the formation of a precipitate when part of this colony was mixed with absolute alcohol. The established conditions for obtaining a high number of isolates producing EPS were 10% sucrose, pH 7.5 and 28 ºC. This method proved to be effective and economical because several strains could be tested on the same plate, with immediate confirmation.

Salmonella Typhimurium, Infantis, Derby, and Enteritidis survival in pasty dulce de leche

Dulce de leche is a food obtained by concentration and heating of milk with the addition of sucrose. The common practice of opening the dulce de leche containers in retail markets can lead to food contamination by Salmonella. The objective of this study was to evaluate the survivability of Salmonellaenterica subsp. enterica serotypes Typhimurium, Enteritidis, Infantis and Derby in pasty dulce de leche. Aliquots of this sweet were experimentally contaminated with these microorganisms and later analyzed to evaluate microorganism viability after storage for 0, 1, 2, 3, 5, 10, and 20 days. Salmonella was recovered up to the 20th day. These results are a warning about the need to adopt proper sanitary-hygienic measures for handling and packaging this food aiming at food safety.

Genetic diversity and comparison of physicochemical and nutritional characteristics of six quinoa (Chenopodium quinoa willd.) genotypes cultivated in Chile

The present study was focused on the analysis of agronomical, nutritional, physicochemical, and antioxidant properties of six genetically different quinoa (Chenopodium quinoa Willd) genotypes cultivated in three distinctive geographical zones of Chile. Ancovinto and Cancosa genotypes from the northern Altiplano (19 ºS), Cáhuil and Faro from the central region (34 ºS), and Regalona and Villarica from the southern region (39 ºS) are representative of high genetic differentiation among the pooled samples, in particular between Altiplano and the central-southern groups. A Common-Garden Assay at 30 ºS showed significant differences among seed origins in all morphometric parameters and also in yields. Altiplano genotypes had larger panicule length but no seed production. A significant influence of the different quinoa genotypes on chemical composition and functional properties was also observed. Protein concentration ranged from 11.13 to 16.18 g.100 g-1 d.m., while total dietary fiber content ranged from 8.07-12.08 g.100 g-1 d.m., and both were the highest in Villarrica ecotype. An adequate balance of essential amino acids was also observed. Sucrose was the predominant sugar in all genotypes. Antioxidant activity was high in all genotypes, and it was highest in Faro genotype (79.58% inhibition).

Isolation of a yeast strain able to produce a polygalacturonase with maceration activity of cassava roots

The objective of the present study was the isolation of a yeast strain, from citrus fruit peels, able to produce a polygalacturonase by submerged fermentation with maceration activity of raw cassava roots. Among 160 yeast strains isolated from citrus peels, one strain exhibited the strongest pectinolytic activity. This yeast was identified as Wickerhamomyces anomalus by 5.8S-ITS RFLP analysis and confirmed by amplification of the nucleotide sequence. The yeast produced a polygalacturonase (PG) in Erlenmeyer shake flasks containing YNB, glucose, and citrus pectin. PG synthesis occurred during exponential growth phase, reaching 51 UE.mL-1 after 8 hours of fermentation. A growth yield (Yx/s) of 0.43 gram of cell dry weight per gram of glucose consumed was obtained, and a maximal specific growth rate (µm) of 0.346 h-1 was calculated. The microorganism was unable to assimilate sucrose, galacturonic acid, polygalacturonic acid, or citrus pectin, but it required glucose as carbon and energy source and polygalacturonic acid or citrus pectin as inducers of enzyme synthesis. The crude enzymatic extract of Wickerhamomyces anomalus showed macerating activity of raw cassava. This property is very important in the production of dehydrated mashed cassava, a product of regional interest in the province of Misiones, Argentina.

Stability of frozen marolo pulp during storage

Marolo, also known as araticum or head-to-black, is a globular berry, a species native to the Brazilian savannah. The aim of this study was to evaluate the physical, chemical, and microbiological stability of frozen marolo pulp during 12 months of frozen storage. It was observed that the levels of ash (0.28-0.22%), protein (0.77-0.71%), lipids (1.75-1.73%), carbohydrates (12.1-10.15%), calorie (67.23-59.01 kcal), sucrose (2.50-1.29%), citric acid (435.63-197.5 µg.g-1), tartaric acid (4.38-1.88 µg.g-1) , acetic acid (470.38-279.25 µg.g-1), ascorbic acid (3.00-0.00 µg.g-1), total pectin (0.67-0.39%), pH (3.88-3.83), and b* chromaticity coordinates (24.85-20.53) decreased reduced during storage, whereas the levels of moisture (85.10-87.19%), color parameters (L* 58.89-62.62 and a* 5.37-7.86), reducing sugars (4.53-5.62%), total soluble sugars (7.1-7.36%), soluble solids (7.0-8.4 ºBrix), total acidity (0.9-1.0%), malic acid (514.13-781.25 µg.g-1), soluble pectin (0.16-0.24%), and antioxidant (6.85-37.35% of DPPH discoloration) increased over the one-year of storage period. According to the physical, chemical, and microbiological parameters assessed, the product can be stored for 12 months without loss of quality with addition of citric acid as a preservative.