Larine Kupski

Changes in lipid, fatty acids and phospholipids composition of whole rice bran after solid-state fungal fermentation

The aim of this study was to evaluate fermented rice bran phospholipids, lipids and fatty acid content in a fermentation solid system with Rhizopus oryzae fungus. For this, aliquots were withdrawn every 24h over 120 h. The content of phospholipids was determined by colorimetric method. Esterified fatty acids were separated by gas chromatography, then identified and quantified. The total lipids from fermented rice bran (FB) decreased from 20.4% to 11.2% in the range between 0 h and 120 h of fermentation while phospholipid contents were increased up to 2.4 mg P g(lipid)(-1). In fermented bran, oleic, palmitic and linoleic acids prevailed, with a decrease in saturated fatty acids (20%) and increase in the unsaturated ones (5%). This study showed that rice bran fermentation with R. oryzae can be applied to the production of phospholipids altering the saturated to unsaturated fatty acid ratio.

Physico-chemical characterization of fermented rice bran biomass Caracterización fisico-química de la biomasa del salvado de arroz fermentado

The experiment was conducted to evaluate the fermentation effect with Rhizopus oryzae in the composition of whole rice bran, which was used as substratum for the fermentative procedure in tray bioreactors at 30 °C for 120 h. During the fermentation, samples were withdrawn in different times (0, 24, 48, 72, 96, and 120 h) for physico-chemical determination using standard procedures. Reductions in moisture, fat, phytic acid, and reducing sugars content of rice bran were respectively 24.6%, 40%, 50%, and 60%. The fermented bran presented an increase of 30% in ash content, 50% in fibers, and 40% in proteins. The digestible amino acid determination indicated 27.6% increase in the digestibility of produced proteins. El experimento fue llevado a cabo para evaluar el efecto de la fermentación con Rhizopus oryzae en la composición de salvado de arroz, el cual fue usado como sustrato para el proceso de fermentación en biorreactores de bandeja a 30 °C durante 120 horas. Durante la fermentación, se tomaron muestras en diferentes momentos (0, 24, 48, 72, 96 y 120 h) para su determinación físico-química usando métodos estándar. La reducción en contenido de humedad, grasa, ácido fítico y azúcares reductores del salvado de arroz fueron respectivamente 24,6%, 40%, 50% y 60%. El salvado fermentado presentó un incremento en 30% de contenido de cenizas, 50% de fibras y 40% de proteínas. La determinación de aminoácidos digeribles indicó un aumento de 27,6% en la digestibilidad de proteínas producidas.

Phenolic compound in beans as protection against mycotoxins.

Phenolic compounds, their inhibitory activity against fungal amylase and the occurrence of aflatoxins were determined in edible beans. The free, conjugated and bounded phenolic compounds and their phenolic acid profiles were determined in ten bean varieties. A method for aflatoxin B1, B2, G1 and G2 determination and confirmation by LC-MS/MS was validated. The red and carioca beans presented the highest total phenolic content (1.8 and 1.2mg.g(-1), respectively); the fradinho and white beans the lowest (0.18 and 0.19mg.g(-1), respectively). In the free and conjugated forms, chlorogenic acid was present in 60% of the samples, while in the bounded phenolic, ferulic acid was in 90% of the samples. The phenolic extracts were able to inhibit fungal amylase, and the PCA analysis confirmed that the relation between the chlorogenic and gallic acids is important to this effect. The absence of aflatoxins in samples confirm the protector effects of these phenolic compounds.

Principal components analysis: an innovative approach to establish interferences in ochratoxin A detection.

This work aimed to establish an innovative approach to evaluate the effect of cereals composition on ochratoxin A extraction by multivariate analysis. Principal components analysis was applied to identify the effect of major matrix components on the recovery of ochratoxin A by QuEChERS method using HPTLC and HPLC, and to validate the method for ochratoxin A determination in wheat flour by HPLC. The matrices rice bran, wheat bran and wheat flour were characterized for their physical and chemical attributes. The ochratoxin A recovery in these matrices was highly influenced (R=0.99) by the sugar content of the matrix, while the lipids content showed a minor interference (R=0.29). From these data, the QuEChERS method was standardized for extracting ochratoxin A from flour using 1% ACN:water (2:1) as extraction solvent and dried magnesium sulfate and sodium chloride as salts. The recovery values ranged from 97.6% to 105%. The validated method was applied to evaluate natural occurrence of ochratoxin A in 20 wheat flour samples, which were contaminated with ochratoxin A levels in the range of 0.22-0.85 μg kg(-1).

Application of protein-phenolic based coating on tomatoes (Lycopersicum esculentum)

The aim of this study was to investigate the use of protein-phenolic based coating made from fermented rice bran on cherry tomatoes (Lycopersicum esculentum). Tests were performed with glycerol 3% (v/v), glycerol with protein-phenolic rice bran extract (5%), glycerol with protein-phenolic extract after 96 hours of fermentation (5%), and a control (without coating). The coated cherry tomatoes were kept at room temperature for 28 days. Mass loss, pH and acidity, total soluble solids, and carotenoids were determined every 96 hours. The coating made from the biomass extract reduced the carotenoid and acidity levels in the fruits studied by 17 and 21.1%, respectively, compared to the control. The coating proved an efficient barrier to water vapor with mass loss of 57% less than the control suggesting that it can be used as an alternative for vegetable tissue conservation.