Anthocyanins standards (cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside) isolation from freeze-dried açaí (Euterpe oleraceae Mart.) by HPLC

Availability of analytical standards is a critical aspect in developing methods for quantitative analysis of anthocyanins. The anthocyanins cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside were isolated from samples of freeze-dried açaí (Euterpe oleraceae Mart.), which is a round and purple well-known palm fruit in Brazil, and then used as standards. The isolation of the anthocyanins was performed by High Performance Liquid Chromatography (HPLC), using an adapted six-channel selection valve. The identification of anthocyanin pigments in açaí was based on mass spectrometric data for molecular ions and MS-MS product ions and on previous published data. After the collection procedure, standards with a high purity grade were obtained and an external standard curve of each anthocyanin was plotted.

Investigation of glutathione peroxidase activity in chicken meat under different experimental conditions

Due to the fact that previous studies on the enzymatic activity of Glutathione peroxidase (GSH-Px) diverge widely in their methodology and results, this study aimed to investigate the influence of different analytical conditions on GSH-Px activity in chicken thighs from broilers that were fed different diets with different sources and concentrations of selenium. GSH-Px activity was evaluated six hours after slaughter and 120 days after frozen storage at -18 ºC. The different analytical conditions included time of pre-incubation (0, 10 and 30 minutes), reaction medium, types of substrate (H2O2 (0.72 mM, 7.2 mM, and 72 mM) and Terc-butil hydroperoxide 15 mM), and different buffer concentrations (buffer 1, potassium phosphate 50 mM pH 7.0 + EDTA 1 mM + mercaptoethanol 1 mM, and buffer 2, tris-HCl 50 mM pH 7.6 + EDTA 1 mM + mercapthanol 5 mM). The results show that the highest GSH-Px activity was observed when enzyme and substrate were in contact at 22 ºC without any pre-incubation, and that, when used at concentrations above 0.72 mM, hydrogen peroxide saturated the GSH-Px enzyme and inhibited its activity. The enzyme presented higher affinity to hydrogen peroxide when compared to terc-butil peroxide, and the addition of a buffer containing mercaptoethanol did not increase GSH-Px enzymatic activity. The activity of GSH-Px was not influenced by the source and concentration of selenium in the diet either. The obtained results allowed the determination of the best temperature of contact between the enzyme and substrate (22 ºC), the optimum concentration, and the type of substrate and buffer to be used. This information is extremely useful for future studies on GSH-Px activity in meat due to the divergence and little information found in the literature.

Oxidative enzymes activity in sugarcane juice as a function of the planting system

In Brazil, the largest producer of sugarcane in the world, the industrial process transforms this crop into ethanol and/or granulated sugar. Some cultivars exhibit enzymatic browning in the extracted sugarcane juice at levels harmful to the manufacturing process of white granulated sugar. The objective of this study was to assess the effect of sugarcane straw used as soil coverage, the use of different planting systems, and treatments with hydrogel polymer on enzymatic activity. The cultivar RB 86 7515 was sampled for 8 months; the first sample was obtained by cutting the upper portion of the stalk at the internode, which was taken to the laboratory for determination of the enzymatic activity of polyphenoloxidase (PPO) and peroxidase (POD). The soil coverage with different forms of straw as well as the planting systems did not change the enzymatic activity of polyphenoloxidase (PPO) and peroxidase (POD). The polyphenoloxidase (PPO) activity increased with the use of a polymer due to increased polyphenoloxidase (PPO) activity in the groove system. The enzymes studied showed changes in activity during the experimental period. The production of sugar at the end of the season (August to November) avoids the periods of highest enzymatic activity.

Ultrafiltration performance of PVDF, PES, and cellulose membranes for the treatment of coconut water (Cocos nucifera L.)

Ultrafiltration (UF) inhibits the enzymatic activity which is responsible for color changes of coconut water without the need for heat treatment. In the present study, UF performance in terms of the permeate flux and enzymatic retention of the coconut water was evaluated at laboratory unit (LU) and pilot unit (PU). The membranes studied were polyethersulfone 150 kDa (UP150), polyvinylidene fluoride 150 kDa (UV150) and cellulose 30 kDa (UC030). The UP150 membrane showed the best permeate flux. The UC030 membrane showed the lowest flux, but it resulted in 100% enzymatic retention, while the other membranes showed enzymatic retentions between 71 and 85%. The application of the UC030 in the pilot unit (PU) resulted in a flux value higher than that obtained in the LU due to the tangential velocity effect. The UC030 membrane has proved adequate for industrial applications.

Adhesion and production of degrading enzymes by bacteria isolated from biofilms in raw milk cooling tanks

Biofilms in milk cooling tanks compromise product quality even on farms. Due to the lack of studies of this topic, this study evaluated the microbiological conditions of raw milk cooling tanks on farms and characterized the microorganisms isolated from these tanks. Samples were wiped off with sterile swabs from seven milk cooling tanks in three different points in each tank. Mesophiles and psychrotrophic counts were performed in all samples. The isolation of Pseudomonas spp., Bacillus cereus and atypical colonies formed on selective media were also performed, totalizing 297 isolates. All isolates were tested for protease and lipase production and biofilm formation. Of the total isolates, 62.9% produced protease, 55.9% produced lipase, and 50.2% produced biofilm. The most widespread genus inside the milk cooling tank was Pseudomonas since it was not possible to associate this contamination with a single sampling point in the equipment. High counts of microorganisms were found in some cooling tanks, indicating poor cleaning of the equipment and providing strong evidences of microbial biofilm presence. Moreover, it is worth mentioning the milk potential contamination with both microbial cells and their degrading enzymes, which compromises milk quality.

Multivariate study of Nile tilapia byproducts enriched with omega-3 and dried with different methods

Abstract The present work aimed at studying the effect of different drying methods applied to tilapia byproducts (heads, viscera and carcasses) fed with flaxseed, verifying the contents of omega-3 fatty acids. Two diets were given to the tilapia: a control and a flaxseed formulation, over the course of 60 days. After this period, they were slaughtered and their byproducts (heads, viscera and carcasses) were collected. These fish parts were analyzed in natura, lyophilized and oven dried. Byproducts from tilapia fed with flaxseed presented docosapentaenoic, eicopentaenoic and docosahexanoic fatty acids as a result of the enzymatic metabolism of the fish. The byproducts from the oven drying process had lower levels of polyunsaturated fatty acids. In the multivariate analysis, the byproducts from fish fed with flaxseed had a greater composition of fatty acids. The addition of flaxseed in fish diets, as well as the utilization of their byproducts, may become a good business strategy. Additionally, the byproducts may be dried to facilitate transport and storage.

Antioxidant activity of black bean (Phaseolus vulgaris L.) protein hydrolysates

Abstract The objective of this work was to study the effect of enzymatic hydrolysis of black bean protein concentrate using different enzymes. Bean proteins were extracted and hydrolyzed over a period of 120 min using the enzymes pepsin or alcalase. The protein hydrolysates’ molecular weight was assayed by electrophoresis and the antioxidant activity was evaluated by the capturing methods of free radicals ABTS●+ and DPPH. Electrophoretic results showed that the bands above 50 kDa disappeared, when the beans protein was subjected to hydrolysis with pepsin. The bean protein hydrolysate obtained by hydrolysis with alcalase enzyme, showed higher antioxidant activity for inhibition of the radical ABTS●+. However, the hydrolysates obtained by hydrolysis with pepsin had higher antioxidant activity for inhibition of the radical DPPH. The use of pepsin and alcalase enzymes, under the same reaction time, produced black bean protein hydrolysates with different molecular weight profiles and superior antioxidant activity than the native bean protein.

Influence of the degree of hydrolysis and type of enzyme on antioxidant activity of okara protein hydrolysates

Abstract The objective of this work was to evaluate the antioxidant activity of protein hydrolysates obtained by the enzymatic hydrolysis of okara using an endopeptidase (Alcalase) and exopeptidase (Flavourzyme). The reaction was monitored by the pH-stat procedure in which five aliquots were collected during the hydrolysis by each enzyme, corresponding to different degrees of hydrolysis (DH). The antioxidant activities of the aliquots were evaluated by the ABTS, DPPH and FRAP methods. For the hydrolysates obtained using Alcalase, the antioxidant activities increased from: 68.6 to 99.5% (ABTS), 14.5 to 17.7% (DPPH) and 222.6 to 684.9 µM Trolox (FRAP), when the DH varied from 0 to 33.6%. With respect to Flavourzyme, the results were: 67.2 to 88.2% (ABTS), 9.5 to 18.5% (DPPH) and 168.0 to 360.3 µM Trolox (FRAP), when the DH increased up to 5.8%. The results showed that the protein hydrolysates had antioxidant capacities, which were influenced by the degree of hydrolysis and the type of enzyme.

Using Tomato Analyzer software to determine embryo size in x-rayed seeds

A primary interest of image analysis of X-rayed seeds is to identify whether the extent of fill in the embryo cavity is associated with to seed physiological quality. The objective of this research was to verify the accuracy of the freely available Tomato Analyzer (TA) software developed at The Ohio State University to determine the ratio of embryo size over total seed area. Seeds of pumpkin, watermelon, cucumber and cotton were X-rayed and analyzed by the software which defines seed and embryo boundaries and automatically generates numerical values to quantify that ratio. Results showed that the TA has the sensitivity to evaluate the extent of embryo growth within the cucurbits and cotton seeds and is a promising alternative for this assessment in other seed species.