Gargi Dey

Enhanced production of amylase by optimization of nutritional constituents using response surface methodology

Abstract Response surface methodology was employed to study the cumulative interactive effect of the macronutrients of the media and to optimize their concentration to enhance the production of maltooligosaccharide-forming amylase from Bacillus circulans GRS 313. A 23 factorial central composite experimental design was used to study the combined effect of the nutritional constituents like soybean meal, yeast extract and wheat bran. The p-value of the coefficient for linear effect of soybean meal concentration was found to be 0.081, suggesting that this was the principal experimental variable having the greatest effect on the production of maltooligosaccharide-forming amylase. The optimal combination of the media constituents for amylase production from the contour plots were: soybean meal =4.84 g /100 ml , yeast extract =1.58 g /100 ml , wheat bran =2.84 g /100 ml . The optimization of the media increased the amylase yield by 1.25 times.

Immobilization of alpha-amylase produced by Bacillus circulans GRS 313

A maltooligosaccharide-forming amylase from B circulans GRS 313 was immobilized by entrapment in calcium alginate beads. The immobilized activity was affected by the size of the bead and bead size of 2mm was found to be most effective for hydrolysis. Kinetics constants, Km and Vmax were estimated and were found to be affected by the bead size. The catalytic activity of the enzyme was studied in presence of various starchy residues and metal ions. HgCl2, CuSO4 and FeCl3 caused inhibition of the enzyme. The reaction conditions, pH and temperature, was optimized using response surface methodology. At the optimum pH and temperature of 4.9 and 57oC, the apparent activity was 25.6U/g of beads, resulting in almost 2-fold increase in activity. The immobilized enzyme showed a high operational stability by retaining almost 85% of the initial activity after seventh use.

Detection of major phenolic acids from dried mesocarpic husk of mature coconut by thin layer chromatography

Abstract This is a report of extraction and identification of phenolic acids present in the dried mesocarpic husks of mature coconut fruit. The total phenolic content of the husk material was 13.0 mg/g dry wt. 4-Hydroxybenzoic acid (4-HBA) and ferulic acid contents were identified and analysed in the husk fractions extracted by mild alkali hydrolysis (with 0.1 M NaOH). Detection of ether-linked phenolic acids (by treatment with 2 M NaOH) yielded 2.2 mg/g dry wt. of 4-HBA and 0.1 mg/g dry wt. of ferulic acid. Our results demonstrate that mesocarpic husk materials can form an alternative source of 4-HBA.

Purification and characterization of maltooligosaccharide-forming amylase from Bacillus circulans GRS 313

A maltooligosaccharide-forming amylase that hydrolyzes starch into maltotriose and maltopentaose was found in the culture filtrate of a strain of Bacillus circulans GRS 313 isolated from local soil. The enzyme was purified by organic solvent fractionation, Sephadex G-100 gel filtration and CM-Sephadex column chromatography. Optimum pH and temperature of amylase were evaluated using response surface methodology (RSM) and were found to be 48°C and 4.9, respectively. The enzyme was stable up to 60°C and its pH stability was in the range of 5.0–8.0. The Km and Vmax of the amylase with starch were 11.66 mg/ml and 68.97 U, respectively, and the energy of activation, Ea, was 7.52 kcal/mol. Dextrin inhibited the enzyme competitively, with a Ki of 6.1 mg/ml, and glucose caused noncompetitive inhibition with a Ki of 9.5 mg/ml. The enzyme was inhibited by Hg2+, Mn2+, Fe3+ and Cu2+ and enhanced by Co2+ and Mg2+. EDTA reversed the inhibitory effect of the metals. Paper chromatographic and high-performance liquid chromatography analysis of the products of the amylolytic reaction showed the presence of maltotriose, maltotetraose, maltopentaose, maltose and glucose in the starch hydrolysate. Journal of Industrial Microbiology & Biotechnology (2002) 28, 193–200 DOI: 10.1038/sj/jim/7000220

Immobilization of α-amylase from Bacillus circulans GRS 313 on coconut fiber

A simple and inexpensive method for immobilizing α-amylase from Bacillus circulans GRS 313 on conconut fiber was developed. The immobilization conditions for highest efficiency were optimized with respect to immobilization pH of 5.5, 30°C, contact time of 4 h, and enzyme to support a ratio of 1:1 containing 0.12 mg/mL of protein. The catalytic properties of the immobilized enzyme were compared with that of the free enzyme. The activity of amylase adsorbed on coconut fiber was 38.7 U/g of fiber at its optimum pH of 5.7 and 48°C, compared with the maximum activity of 40.2 U/mL of free enzyme at the optimum pH of 4.9 and 48°C. The reutilization capacity of the immobilized enzyme was up to three cycles.

Perspectives on global fermented foods

Purpose – The purpose of this paper is to outline the present status of various fermented foods and beverages across the globe and reviews on the microbiology and therapeutic effects of fermented foods. Design/methodology/approach – Fermented foods play an important socio-economic role in developing countries as well as making a major contribution to the nutrition requirements of natural populations. These foods have attracted attention all over the world as foods that might promote longevity. The approach is based on observations of online research with respect to fermented foods and their origins, analysis of research papers in journals and systematic research on the microbiology and health benefits of fermented products. Findings – In general, traditional fermented foods produced with indigenous practices throughout the world are made under primitive conditions, which result in low yield and poor quality. But since, these foods are not only traditional but also functional foods. They are experiencing a...

Fermentation responses and in vitro radical scavenging activities of Fagopyrum esculentum

In this study, the impact of fermentation of Fagopyrum esculentum (buckwheat) by Lactobacillus delbrueckii subsp. lactis was investigated. The interaction between starter culture and buckwheat dough matrix was evaluated with respect to microbial count, final pH, organic acids, total phenolic content and antioxidant potential. An increase of one log cycle from 8.76 to 9.92 log CFU(Colony Forming Unit)/g was observed during fermentation. Lactic acid content increased up to 1350 μg/g within 24 h of fermentation. The most significant result of this study was an observed increase in the total phenolic content of the dough, from 2.73 to 7.64 mg GAE(Gallic Acid Equivalence)/g. Antioxidant potential of fermented buckwheat also showed an increased percentage of 2,2-diphenyl-2-picrylhydrazyl scavenging activity from 44.32% to 88.98% and ferric reducing antioxidant power potential increased from 14.43 to 25.68 μM Fe(II)/g after 72 h of fermentation. We conclude that lactic acid fermentation of buckwheat dough has a potential to be a functional food, with enhanced antioxidant activity.

Non-dairy Probiotic Foods: Innovations and Market Trends

The existence of an enormous list of traditional fermented foods produced and consumed globally may be considered as the genesis of non-dairy probiotic products. While LABs used as starter cultures showed attributes desirable for a probiotic culture, it was just a matter of time, when scientists and technologists figured out that food matrices which could be fermented could also be used as probiotic delivery vehicles and some starter cultures could perform the dual task of fermentation and probiosis. Meanwhile health has continued to be at the forefront of new product development strategies. The observations that plant carbohydrates and phenolics may act synergistically with probiotics in formulations for gut health have given a shot in the arm for non-dairy probiotic product developers. Today, diverse food innovations are possible through manipulations of synergies between probiotic strain and the components of food matrices, although technological bottlenecks needed to be addressed. However, it is expected that new non-dairy product development will pose its own set of challenges. Each food matrix is unique; the industries need to standardize and optimize the basic formulation for each product that will have the required sensory and physical chemical characteristics, extended shelf life, and chemical stability, all at a reasonable cost. Much has been said about technological complexities and challenges of non-dairy food formats, but despite them, several commercially viable products are already gracing the shelves of supermarkets globally. Food formats like fruit and vegetables juices and cut and whole tissue and cereals seem to be the current favorite, while meat matrix is still in the research stage. The key to success will be to convince consumers to pay the cost for a new product, and it can be achieved through communication of unambiguous and truthful health claims to the consumers.

Matrix-wise evaluation of in vivo and in vitro efficiencies of L. rhamnosus GG-fortified beverages

The interactions between phenolic compounds and gut microbiota, have gained much attention due to their beneficial effect on humans. The study was also conceived keeping in view the growing popularity of probiotics and emerging interest in designing plant based matrices for probiotic delivery. The synergistic relationship between probiotic, Lactobacillus rhamnosus GG (LR) (ATCC 53103) and phenolic compounds of fruit matrices, sea buckthorn (SBT) and apple juice (APJ) was evaluated on TNBS induced enterocolitis in a zebrafish model (Danio rerio). Addition of LR to SBT matrix conferred higher protection against inflammation than LR in APJ matrix. This could be due to higher content of phenolic compounds in SBT. Isorhamnetin was identified as the predominant phenolic in SBT. The juice matrices were also evaluated for their flow and viscoelastic properties. The consistency index (K) and flow behaviour index (η) were derived from evaluating the shear strength. All the tested juice matrices demonstrated shear-thinning properties. Effect of the matrices on other functionalities of LR during storage period of 14 days was also evaluated. No significant changes were observed on cell surface hydrophobicity depicting protective action of the matrix components on the probiotic strain. Gastrointestinal tolerance increased on Day 7 and 14. Principal Component Analysis of the anti-microbial potential of the probiotic beverage formulations against pathogenic and food spoilage strains showed higher antagonistic ability of LR in SBT during the 14 days storage. The key findings suggest probiotic strain may behave differently in different food matrices. The sustainable functionality of the probiotic strain can be achieved even during the shelf period by optimum design of the delivery matrix.

Fermentation responses andin vitroradical scavenging activities ofFagopyrum esculentum: Short Communication

In this study, the impact of fermentation of Fagopyrum esculentum (buckwheat) by Lactobacillus delbrueckii subsp. lactis was investigated. The interaction between starter culture and buckwheat dough matrix was evaluated with respect to microbial count, final pH, organic acids, total phenolic content and antioxidant potential. An increase of one log cycle from 8.76 to 9.92 log CFU(Colony Forming Unit)/g was observed during fermentation. Lactic acid content increased up to 1350 μg/g within 24 h of fermentation. The most significant result of this study was an observed increase in the total phenolic content of the dough, from 2.73 to 7.64 mg GAE(Gallic Acid Equivalence)/g. Antioxidant potential of fermented buckwheat also showed an increased percentage of 2,2-diphenyl-2-picrylhydrazyl scavenging activity from 44.32% to 88.98% and ferric reducing antioxidant power potential increased from 14.43 to 25.68 μM Fe(II)/g after 72 h of fermentation. We conclude that lactic acid fermentation of buckwheat dough has a potential to be a functional food, with enhanced antioxidant activity.