Optimisation of important processing conditions for rice bran sourdough fermentation using Lactobacillus plantarum

The potentials of rice bran sourdough in bread making are recently gaining popularity. However, there is no information on the influence of processing conditions on the quality attributes of rice bran sourdough. To inves- tigate the influence of fermentation time and temperature on the levels of acidity (pH and TTA) in rice bran sour- dough fermented with L. plantarum, we applied response surface methodology (RSM). Furthermore, we studied the effect of different fermentation time and temperature on the total phenolic and volatile compounds in the sourdough. GC/MS measurements for the evolution of aroma volatile compounds (VOCs) in the rice bran sourdoughs were conducted. The higher and longer the fermentation temperature and time, the higher the acidity levels in the sour- doughs. Fermentation temperature and time do not have a significant effect on the total phenolic sourdough con- tents. Forty-seven VOCs were detected in the rice bran sourdoughs. The major VOCs were acetic acids, ethanol, 2-Methoxy-4-vinylphenol, Hexadecanoic acid, 1-(hydroxymethyl)-1,2-ethanediyl ester, acetoin, and 2-methoxy-Phe- nol. The sourdough fermented at 35°C for 13 ho contained the largest number (27) of aroma compounds and had the highest acidity. These fermentation conditions are close to the optimal parameters (temperature – 33°С, duration – 12.5 hours), obtained as a result of applying RSM for rice bran fermentation. Thus, high quality bran sourdough can be produced at the temperature of 33°C for 12.5 hours. The results of this study will be useful to produce a quality rice bran sourdough bread with appealing aroma and a long shelf-life

Functional properties, antioxidant activities and storage stability of cookies from germinated brown rice and rice-potato starch composite flour

Cookies are convenient food for people of all ages. Consumers' interest for gluten free cookies is increasing recently due to awareness on gluten allergy. This study evaluated the functional properties and antioxidant activities of germinated brown rice flour (GBRF) and non-germinated brown rice flour (NGBRF), and GBRF-potato starch blend (3:1), and NGBRF-potato starch blend (3:1). Storage stability and sensory acceptance of cookies produced from the various flour samples were also evaluated. The flours had significantly different values in most of the functional properties. However, the Housner's ratio (1.18- 1.35), Carr index (14.94-25.67) and water absorption index (1.88-2.14 g/g) of the flours were not significantly different. GBRF and germinated brown rice flour cookies (GBRFC) had the highest antioxidant activities with DPPH values of 40.61 µM TE/g and 37.67 µM TE/g, respectively, and FRAP values of 39.84 µM TE/g and 38.29 µM TE/g, respectively. The GBRFC had higher total phenolic content (152.30 mg GAE/100g) than cookies from GBRF-starch blend (107.37 mg GAE/100 g). Sensory evaluation results showed that all the cookies were similarly rated for aroma, texture, mouth feel, crispiness and overall acceptance. However, cookies prepared from wheat flour, and germinated brown rice-potato starch (GBRPS) had the highest sensory scores for overall acceptance. The hardness of cookies produced from GBRPS was similar to that of the freshly produced cookies after 7 days of storage at room temperature

A Review of Cyanogenic Glycosides in Edible Plants

Cyanogenic glycosides are natural plant toxins that are present in several plants, most of which are consumed by humans. Cyanide is formed following the hydrolysis of cyanogenic glycosides that occur during crushing of the edible plant material either during consumption or during processing of the food crop. Exposure to cyanide from unintentional or intentional consumption of cyanogenic glycosides may lead to acute intoxications, characterized by growth retardation and neurological symptoms resulting from tissue damage in the central nervous system (CNS). Processing methods can detoxify cyanogenic glycosides and reduce the risk of cyanide poisoning. The efficiency of cyanide removal, however, depends on the processing technique employed and the extent of processing. Processing operations such as fermentation, boiling/cooking, and drying, applied to process food‐containing cyanogenic glycosides have been reported to reduce cyanide content to acceptably safe levels. The present review discusses the level of cyanogenic glycosides in specific plant foods, health implications of consuming cyanogenic plants and effect of various processing method on cyanogenic glycosides with updated information gathered from the published reports on cyanogenic glycosides

Quality of gluten-free cookies from germinated brown rice flour

Gluten-free food products are becoming popular due to increased consumers awareness on celiac disease. In this study, novel gluten-free cookies were produced from 100% germinated and non-germinated brown rice flour, and the blend of rice flour with 25% potato starch. The quality of the cookies was evaluated in terms of proximate composition, physical properties (diameters, weights, thickness and spread ratio), textural properties (dough and cookies hardness) and sensory attributes. Results obtained showed that germination increased the protein contents from 7.92% to 7.99%, ash from 1.29% to 1.38%, total dietary fibre from 5.27% to 6.13% and fat from 2.24% to 2.98% in germinated brown rice flour. Germinated brown rice dough and cookies had lower hardness value compared to non-germinated brown rice dough and cookies. Addition of potato starch to germinated brown rice flour increased the lightness (79.1-78.8) and yellowness (24.6-24.2) colour of the cookies, as well as the spread ratio of the cookies (8.28-8.37). Sensory evaluation results showed that all the cookies were similarly rated in terms of appearance, colour, aroma and taste, with cookies containing 75% germinated brown rice flour and 25% potato starch having the highest sensory score for texture (6.63) and overall acceptability (6.90). This study showed that the blend of germinated brown rice flour and potato starch can be used for the preparation of quality and acceptable gluten-free cookies

Influence of starter culture on the physicochemical properties of rice bran sourdough and physical quality of sourdough bread

The effect of mixed strain culture of lactic acid bacteria (LAB) and Yeast, and yeast or L. brevis, L. plantarum, or L. sanfranciscencison the physicochemical properties (pH, TTA, organic acid, ethanol, and sugar content) of rice bran sourdough was investigated. Starter culture with optimum physicochemical properties was used to ferment rice and wheat bran for sourdough production. Rice and wheat bran sourdough and non-fermented rice and wheat bran were mixed with wheat flour at 10% substitution level for bread production. Results showed that rice bran fermented with L. plantarumhad the best physicochemical properties compared to rice bran sourdough produced by other LAB or mixed culture. The specific volume of bread sample made with rice bran sourdough (4.65 cm3/g) was higher than that of the bread samples made from wheat bran sourdough (4.32 cm3/g) and non-fermented bran (3.74 –4.24 cm3/g), but not significantly different from the control (100% wheat) bread (4.85 cm3/g). The crumb colour of the rice bran and rice bran sourdough substituted bread was lighter than that of the other bread samples. Crust colour of all the bread samples was not significantly different (p > 0.05). At the end of 6 days storage period, bread samples from control and wheat bran sourdough were firmer than that from rice bran sourdough, however, crumb firmness values were highest in non-fermented bran substituted bread. Sensory analysis result revealed that rice bran sourdough bread was more acceptable than wheat bran sourdough bread, and non-fermented rice and wheat bran substituted bread