Zeitschrift für Bioverarbeitung und Biotechnik

Amazake’ is nutrient-rich and physiologically active Japanese traditional food made by fermenting steamed rice with ‘koji’ mold. In this study, vitamin E species were determined as liposoluble antioxidants in amazake and changes in their compositions were examined during fermentation. Six vitamin E species were detected in brown rice amazake (BRA), and the total vitamin E content in BRA was six-fold higher than that in white rice amazake. This was consistent with the high radical scavenging capacity of BRA, which corresponded with the total levels of vitamin E and ferulic acid (FA). Although vitamin E levels in brown rice powder decreased during presaccharification, their levels were almost constant throughout saccharification and remained high in the final BRA product, suggesting the liposoluble antioxidants were stable under amazake preparation conditions. 4-Vinylguaiacol (4-VG) was found in amazake, and its content markedly increased during BRA manufacturing. Rice koji contained high levels of 4-VG produced from FA by the biological action of koji. The liposoluble antioxidative activities in BRA were due to vitamin E and 4-VG, in addition to FA, a phenolic compound thought to be the major radical scavenger. These observations suggested the superiority of traditional fermentation using koji and the advantage of BRA containing liposoluble antioxidants, such as vitamin E and FA.

Injera is yeast-risen flat bread with a unique, slightly spongy texture. It is a national staple in Ethiopia that is eaten daily in virtually every household. Rice injera has a very short life (2-3 days) at room temperature and essentially spoils due to mould growth. The use of weak organic acid as preservative is allowed in acidic foods, primarily as mould inhibitors. In this study, the effects of chemical preservatives: benzoic acid, sodium benzoate, and potassium sorbate and starter cultures (Lactobacillus plantarum+Saccharomyces cerevisiae) on the quality and shelf life of rice injera were investigated. Benzoic acid (0.1%), sodium benzoate (0.1%), potassium sorbate (0.2%) and a 1:1:1 blend of the three (0.2%) were added immediately before baking. Qualitative descriptive analysis (n=10) was used to describe the characteristics of the injera samples. A consumer acceptability panel (n=30) was used to determine the acceptability and shelf life of injera. The preservatives significantly (p<0.05) prolonged the shelf life of injera for up to 10 days with the combination of the three starters achieving the greatest effect. The findings of this study showed that the rice injera prepared with chemical preservatives (0.1 benzoic acid, 0.2% potassium sorbate, 0.1% sodium benzoate and 0.2% of the three preservatives retains maximum overall acceptability. Rice injera produced under controlled fermentation L. plantarum, and S. cerevisiae produce injera with better sensory quality than the traditional by using Irsho. Nine descriptors/attributes describing appearance, aroma/odor, taste, and texture were generated to characterize the sensory properties of rice injera. Softness, rollablity, fluffiness, eye size, whitness of top and bottom surfaces and slight sour taste are main characterstics descriptors of rice injera. Softness, fluffiness, spongness, slight sourness and eye size are attributes associated with quality of rice injera. Therefore, a starter combination of L. plantarum+S. cerevisiae together with 0.2% of the blend of the preservatives (0.1% benzoic acid+0.1% sodium sorbate+0.2% potassium sorbate) in 1:1:1 ratio preservatives can be used to produce acceptable injera with a shelf life of 10 days at room temperature.

Hydrophilic nonporous silica aerogels were synthesized from a low-cost wheat husk silica precursor via ambient pressure drying method for the first time. The prepared aerogels were characterized by using Fourier transform infrared spectra (FTIR), nitrogen adsorption/desorption measurement and scanning electron microscopy- energy dispersive X-ray (SEM -EDX) techniques. The aerogels were used in adsorption of lead (II) ions from aqueous solutions under various conditions such as pH, the adsorbent dosage, the initial lead (II) concentration and the contact time. The optimum adsorption efficiency (99%) was obtained in a pH of 5.5, adsorbent dosage of 4 g L-1, initial lead concentration of 50 mg mL-1 and contact time of 30 minutes. The adsorption data was well described by Langmuir isotherm and pseudo-second-order kinetic model. These results show that low-cost silica aerogel prepared from an agricultural waste can be used as an effective sorbent for lead (II) ions removal.

During recent years there has been a growing interest in the use of ionic liquids as substitutes for organic solvents. That has been due mainly to their unique properties, which highlight their very low volatility. This editorial is focus on analyzing the application of ionic liquids as reaction media in enzyme catalyzed reaction. Specifically, the advantages of using ionic liquids as reaction media for biocatalysts were discussed. Other considerations like green aspect of ionic liquids and the recovery of synthetic products from ionic liquid matrix were also analyzed.

MFC had advantages over the conventional treatment of wastewater regarding nature of converting chemical energy into bio-electricity generation. The study was made for treatment of algal biomass in MFC for electricity generation. The present study deals with the utilization of sewage sludge, which contains a high level of readily biodegradable bio waste and is also one of the major sources of environmental pollution, as a substrate in MFC. Saccharomyces cerevisiae used biocatalyst and potassium ferricyanide as an oxidizer were utilized for the conversion of sewage sludge into voltage utilizing dual chambered MFC. A maximum of the voltage of 0.9-1.0 V was obtained per liter of the sludge with the cathode in continuous mode and the anode in batch feed mode of operation.