Brewer’s rice - A potential substrate for cosmeceutical bio-ingredient production by solid state fermentation using Aspergillus oryzae

Aims@#Brewer’s rice is one of the by-products from rice processing industry that is rich in bioactive compounds but currently underutilized. Exploitation of agro-industrial by-products as substrates in solid-state fermentation processes provides value-addition to these underutilized by-products. The purpose of this research is to evaluate the potentiality of brewer’s rice as a source of cosmeceutical or cosmetic bio-ingredient by utilizing solid-state fermentation process. @*Methodology and results@#Brewer’s rice was submitted to solid-state fermentation with Aspergillus oryzae from MARDI’s Collection of Functional Food Culture (CFFC). Extracts of unfermented and fermented brewer’s rice were later subjected to determination of biological content and biological activities, as well as measurement of their phenolic and organic acids content. The extract of fermented brewer’s rice exhibited an increase in total phenolic and total flavonoid content and showed enhanced 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and ferric-reducing activities. Additionally, it was also found that the tyrosinase and elastase inhibition activities of fermented brewer’s rice extract is significantly higher with nearly 7- and 57-fold, respectively, than the unfermented extract. Ferulic and kojic acid – two of the most important compounds in cosmeceutical formulations, were also detected in fermented brewer’s rice extract. @*Conclusion, significance and impact of study@#Antioxidant, anti-pigmentation and anti-wrinkle properties of brewer’s rice were successfully enhanced by fermentation with A. oryzae. Fermented brewer’s rice extract has high potential to be developed as functional bio-ingredient for cosmeceutical as well as nutraceutical products.

Antibacterial potential of lactic acid bacteria isolated from local pickled Eleiodoxa conferta (kelubi) against selected foodborne pathogens

Aims@#Pickled fruits are a popular condiment not only in Malaysia but throughout the world. Lactic acid bacteria (LAB) are known to be able to produce several antibacterial compounds during the pickling process. Pickled Eleiodoxa conferta or kelubi is among the commonly consumed pickled fruits in Malaysia and may be a promising source of LAB. This study was carried out to isolate and identify LAB from local pickled E. conferta and to determine their antibacterial activity against foodborne pathogens. @*Methodology and results@#The isolation of LAB was conducted using standard methods and the isolated colonies were preliminarily identified based on their morphology on De Man, Rogosa and Sharpe (MRS) agar, Gram-positive staining characteristics and their catalase-negative reactions and subsequently chosen for identification with polymerase chain reaction (PCR) amplification of the 16S rRNA gene and sequencing. A total of four LAB isolates were successfully isolated and identified: Lactobacillus brevis (LABK1 and LABK2), L. plantarum (LABK3) and Leuconostoc mesenteroides (LABK4). The antibacterial activity of the identified LAB was determined against 10 commonly known foodborne bacterial pathogens using LAB cell cultures by agar spot test method. The antibacterial activity was also evaluated using the cell free supernatant (CFS) of the LAB through agar well diffusion method. All four LAB cultures were able to demonstrate antibacterial activity and inhibited five Gram-positive and five Gram-negative bacterial pathogens. @*Conclusion, significance and impact of study@#This study demonstrated that the isolated LAB from E. conferta has antibacterial effects against several foodborne pathogens. These LAB strains may have potential as a natural food preservative.

Estimation of growth in solid state fermentation: A review

@#Carleysmith and Fox (1984) stated “without doubt, the single most vital yet most problematical value sought duringfermentation is biomass estimation”. Achieving a positive result in determining biomass remains a major challenge insolid state fermentation (SSF). Fungi are well-characterised microorganisms and are widely used in SSF due to theirability to colonise and penetrate into the solid substrate. The compressed structure of the mycelia and the solid substratedoes not allow a complete recovery of the biomass, which may not be insurmountable. Since the use of a directtechnique such as the dry weight method is impractical, the use of an indirect estimation technique is the only alternative.This review examines strategies that have been used to estimate biomass in SSF. Many promising indirect estimationtechniques are available, which can be classified into six categories as follows; (i) measuring cell components notpresent in the substrate; (ii) measuring biomass component present in both substrate and biomass; (iii) measuring othersecondary metabolites; (iv) measuring metabolic activity; (v) measuring images from direct microscopic observation and(vi) measuring biomass from the substrate matrix. New potential technique and future directions are also discussed inthis review. Although significant advances have been made with the availability of various techniques; however, progresshas been very unsatisfactory. The evaluation of microbial growth in SSF may sometimes become laborious, impracticaland inaccurate. Essentially, this remains another critical issue for monitoring growth. The information of the profile offungal biomass growth throughout any SSF process constitutes an essential parameter in estimation of kinetic variablesand subsequently, scale-up of the process.

Colour changes as an indicator for estimating fungal growth in solid state fermentation

@#Aims:In this study, measurement of colour changes during solid state fermentation (SSF) are presented as one of the potential techniques that can be used to describe growth, complementary to other biomass estimation, such as weight of fungus, spores concentration, organic matter loss, glucosamine and enzyme activity, which is directly related to growth.Methodology and results: In this study, fungal fermentation of Aspergillus awamoriand A.oryzaeare carried out on complex heterogeneous solid media; wheat bran, soybean hull and rapeseed meal, which are constituted of various soluble and insoluble solid particles. Fermented mass was extracted using distilled water to obtain a cell free extract, which canbe determined quickly and accurately using UV-Visible spectrophotometermeasured absorbance at 300 nm. The results showed a significant correlation between colours produced from fungal SSF and the concentration of spores, weight of fungus cells, organic matter loss, glucosamine and enzyme activity. We found that the colour density proportionally increased when the studied parameters mentioned above increased.For the growth of A. awamoriand A. oryzaeon wheat bran, soybean hulls and rapeseed meal, it was confirmed that colour production was directly proportional to fungal growth. In general, colour-based methods seem to be the most promising approach for biomass estimation in SSF.Conclusions, significance and impacts of study:The theory of measuring colour changes in SSF by UV-visible spectroscopy demonstrates that the colour method gives some valuableinformation than just obtaining a visual observation or spore count to describe growth of fungal mycelium in SSF. The ideas obtained from this exercise might provide a quick and convenient method for quality control of fungal growth. The advantages of this method are that the procedure is simple to carry out, it is non-destructive and no special and expensive reagents are required and the process is very cheap.This newapproach is an important complimentation to the existing techniques especially for basic studies.

Extracted substrate colour as an indicator of fungal growth in solid state fermentation

Aims: In solid state fermentation (SSF), estimation of biomass is difficult as fungal mycelium penetrates deep and remains attached to the solid substrate particles. This study examines and evaluates a new technique based on colour changes of fermented substrates during SSF as an indicator for fungal growth. Methodology and Results: SSF refers to microbial fermentation, which takes place in the absence or near absence of free water, thus being close to the natural environment in which the selected microorganisms, especially fungi, are naturally adapted. Although many promising methods are available, the evaluation of microbial growth in SSF may sometimes become difficult, impractical, and inaccurate. Essentially, this remains another critical issue for monitoring growth. In this study, measurements of colour changes of fermented substrates during SSF are used as indicators for growth and this technique has a potential to be used to quantify growth of microbes. For the growth of Aspergillus awamori and A. oryzae on wheat bran, soybean hulls, and rapeseed meal, it was confirmed that colour changes were directly proportional to the fungal growth. This new approach is an important complementation to the existing techniques, especially for basic studies. The advantages of this method are its ease of use, fast, non-destructive, cheap, and requires no special and expensive reagents. The key finding is that the colorimetric technique demonstrated in this study provides good means to estimate growth than that obtained by visual observation or spores counting.

Nutrients interaction investigation to improve Monascus purpureus FTC5391 growth rate using Response Surface Methodology and Artificial Neural Network

Aims: Two vital factors, certain environmental conditions and nutrients as a source of energy are entailed for successful growth and reproduction of microorganisms. Manipulation of nutritional requirement is the simplest and most effectual strategy to stimulate and enhance the activity of microorganisms. Methodology and Results: In this study, response surface methodology (RSM) and artificial neural network (ANN) were employed to optimize the carbon and nitrogen sources in order to improve growth rate of Monascus purpureus FTC5391, a new local isolate. The best models for optimization of growth rate were a multilayer full feed-forward incremental back propagation network, and a modified response surface model using backward elimination. The optimum condition for cell mass production was: sucrose 2.5%, yeast extract 0.045%, casamino acid 0.275%, sodium nitrate 0.48%, potato starch 0.045%, dextrose 1%, potassium nitrate 0.57%. The experimental cell mass production using this optimal condition was 21 mg/plate/12days, which was 2.2-fold higher than the standard condition (sucrose 5%, yeast extract 0.15%, casamino acid 0.25%, sodium nitrate 0.3%, potato starch 0.2%, dextrose 1%, potassium nitrate 0.3%). Conclusion, significance and impact of study: The results of RSM and ANN showed that all carbon and nitrogen sources tested had significant effect on growth rate (P-value < 0.05). In addition the use of RSM and ANN alongside each other provided a proper growth prediction model.