Araceli Redondo-Cuenca

Soybean seeds and its by-product okara as sources of dietary fibre. Measurement by AOAC and Englyst methods

The composition of soybean seeds and its by-product okara has been studied in this work. Dietary fibre was analysed by Englyst et al. method, by enzymatic-gravimetric methods of AOAC and by the quantification of the monomers obtained from the AOAC residues after acid hydrolysis (AOAC plus hydrolysis). Total dietary fibre by the enzymatic-gravimetric methods of AOAC in okara (55.48g/100g dry matter) is more than twice that of soybean seeds (24.37g/100g dry matter). The proportion IF/SF is 11 in okara and 6 in soybean seeds. Dietary fibre results from enzymatic-gravimetric AOAC methods are higher in okara and soybean seed samples than those from the Englyst method (okara: 41.14g/100g dry matter; soybean seeds: 15.05g/100g dry matter), and AOAC plus hydrolysis (okara: 44.91g/100g dry matter; soybean seeds: 16.38g/100g dry matter). In the case of the insoluble fibre from both samples, AOAC plus hydrolysis gives significantly (p<0.001) higher values than the Englyst method, whilst for soluble fibre the opposite occurs (p<0.001). The main monomers in soybean seeds and okara fibre are glucose, galactose, uronic acids, arabinose and xylose. The proportion of each monomer is similar in soybean seeds and okara, so the healthy properties of soybean seeds fibre are also claimed for okara.

Effects of processing conditions on soluble sugars content of carrot, beetroot and turnip

The effect of processing conditions on the soluble sugars fraction of three vegetables, carrot, beetroot and turnip, was evaluated by high-performance liquid chromatography (HPLC) and by a colorimetric method using potassium ferricyanide. Processing was performed at 121°C during 15 min and three different lots of each vegetable were studied. To verify whether the behaviour was homogeneous, each lot was processed three times, consecutively, under the same conditions. Results were statistically evaluated by two-way ANOVA to elucidate the effects of processing on each vegetable. A significant reduction was observed of soluble sugars, fructose, glucose and sucrose, in the processed samples. A high correlation was observed between the results of total sugars obtained by HPLC and by the colorimetric method.

Sequential extraction of polysaccharides from enzymatically hydrolyzed okara byproduct: Physicochemical properties and in vitro fermentability

Okara, a byproduct of soymilk production, has been upgraded through the use of an enzymatic treatment with Ultraflo L® to give a product (okara(ET)) which has a higher content of soluble dietary fibre and an enhanced ratio of soluble: insoluble fibre than is found in okara without treatment. Polysaccharides were isolated from okara(ET) by sequential extraction to yield soluble fractions in water (22%), CDTA (8.7%), alkali (37.7%) without and NaClO2 (9.1%) and the cellulosic residue represents a (22.5%). The physicochemical properties of okara(ET) were improved due to the enzymatic treatment: oil retention capacity (6.94g/g), water retention capacity (10.76g/g) and swelling capacity (13.85g/g) were higher than in okara that had not undergone enzymatic treatment. The gelation capacity (8%) and the cation exchange capacity (8.96mEq/kg) of okara(ET) were lower than that of other byproducts. Short chain fatty acid production during in vitro fermentation of okara(ET) by a pure culture of Bifidobacterium bifidus was mainly represented by acetic acid, followed by propionic and butyric acids. In addition, the decreases in pH and substrate consumption demonstrated the bifidogenic capacity of okara(ET).

Broad bean and pea by-products as sources of fibre-rich ingredients: potential antioxidant activity measured in vitro

BACKGROUND By-products generated during the processing of plant food can be considered a promising source of dietary fibre as a functional compound. The dietary fibre composition, soluble sugars and antioxidant activity of the extractable polyphenols of pea and broad bean by-products have been analysed in this study. RESULTS Total dietary fibre using AOAC methods plus hydrolysis (broad bean pod: 337.3 g kg⁻¹; pea pod: 472.6 g kg⁻¹) is higher (P < 0.05) in both by-products than with the Englyst method (broad bean pod: 309.7 g kg⁻¹; pea pod: 434.6 g kg⁻¹). The main monomers are uronic acids, glucose, arabinose and galactose in broad bean pods. However, pea pods are very rich in glucose and xylose. The soluble sugars analysed by high-performance liquid chromatography in both by-products have glucose as the most important component, followed by sucrose and fructose. The ferric reducing antioxidant power (broad bean pod: 406.4 µmol Trolox equivalents g⁻¹; pea pod: 25.9 µmol Trolox equivalents g⁻¹) and scavenging effect on 2,2-diphenyl-1-picrylhydrazyl radical (EC₅₀ of broad bean pod: 0.4 mg mL⁻¹; EC₅₀ of pea pod: 16.0 mg mL⁻¹) were also measured. CONCLUSIONS Broad bean and pea by-products are very rich in dietary fibre, particularly insoluble dietary fibre and their extractable polyphenols demonstrate antioxidant activity. Therefore they might be regarded as functional ingredients.

Potential fat-lowering and prebiotic effects of enzymatically treated okara in high-cholesterol-fed Wistar rats.

Abstract This study evaluates the effect of the lipid profile on serum, liver and faeces, and the potential prebiotic effect of diets supplemented with enzymatically treated okara (okaraET) in high-cholesterol fed Wistar rats. Triglyceride levels were significantly reduced in the serum (p < 0.01) and liver (p < 0.01) of okaraET treated rats. Total lipids, triglycerides and bile acids were significantly higher (p < 0.001) in the faeces of rats fed the okaraET diet. The pH of faecal contents from treated okaraET rats was lower (p < 0.001), probably due to the significantly higher (p < 0.001) production of short-chain fatty acids (SCFA). OkaraET, therefore, reduced triglycerides in serum and liver, and increased the excretion of total lipids, triglycerides and bile acids, improving the lipid profile in rats fed with high-cholesterol diets. OkaraET fibre can improve intestinal transit by increasing faecal bulk. The decreased pH and increased SCFA production indicated that okaraET fibre fermentation occurred, suggesting a potential prebiotic effect.

Scavenging Activity on DPPH Radical of the Enzymatically Obtained Oligosaccharides from Himanthalia elongata

The brown seaweed Himanthalia elongata presents great dietary fibre (DF) content (29-37 g/100 g dm). Alginates, laminarans and the sulphated polysaccharides fucans are the DF main constituents. The scavenging activity on DPPH of the enzymatic extracts obtained by hydrolysis with the food grade enzymes Viscozyme, Ultraflo, Glucanex, Peelzym, Celluclast, Novozym, Promozyme, Mannaway, Shearzyme, after a previous treatment to eliminate fat and pigments, protein (Alcalase and Flavourzyme) and available carbohydrate (AMG and Fungamyl) were measured. The highest antioxidant activity was developed by the enzymatic extract from Novozyme and Peelzym. The extracts from Mannaway and Ultraflo showed high amount of oligosaccharides with notable sulphate content and develop high antioxidant activity. However, Promozyme was one of the enzymes that produces high amount of oligosaccharides with high sulphate content, and presented low antioxidant activity. Thus, other factors such as oligosaccharide type, structure or spatial pattern of sulphates may be involved in the development of antioxidant activity.