Surekha Bhatia

Phytohormone-mediated transformation of sugars to starch in relation to the activities of amylases, sucrose-metabolising enzymes in sorghum grain

Indole-acetic acid (IAA) and abscisic acid (ABA) were fed throughcomplete liquid medium (containing 2, 4, 8% sucrose) to detached earheads of sorghum. The effect of these phytohormones on interconvertion ofsugarsand their transformation to starch in relation to the activities ofα-, β-amylases, sucrose-synthase (synthesis), sucrose-phosphatesynthase and soluble invertases was studied in the grain. This effect on theuptake of (U-14C) sucrose by detached ear heads and incorporation of14C into free sugars and starch of grain and into free sugars ofinflorescence parts was also studied. At concentrations of up to 4%sucrose in the culture medium, IAA increased the content of total free sugarsinthe grain. However, accumulation of starch and activities of α- andβ-amylases increased when lAA was present even beyond the 4%sucroseconcentration in the culture medium. At all sucrose concentrations, the effectsof ABA and IAA were opposite. With 4% sucrose, both phytohormones causedmaximum accumulation of starch in the grain. ABA enhanced the relativeproportion of sucrose in the sugar pool with a concomitant reduction in theactivities of soluble acid (pH 4.8) and neutral (pH 7.5) invertases. Incontrast, IAA decreased the sucrose proportion of grain sugars with asimultaneous elevation and reduction in the activities of invertases andsucrose-phosphate synthase, respectively. Irrespective of sucrose concentrationin the culture medium, the activity of sucrose synthase (synthesis) wasenhancedwith IAA as well as ABA at their 10 μM concentration. IAA alsoenhanced incorporation of 14C from (U-14C) sucrose intothe EtOH extract (principally constituted by free sugars) and starch of thegrain, but ABA caused the reverse effect. Based on the results, it is suggestedthat IAA and ABA have contrasting effects on the transformation of sucrose tostarch in sorghum grain where its capacity to synthesise starch is modulatedpositively by IAA and negatively by ABA.

Potential of sugarcane bagasse for production of furfural and its derivatives

Production potential of furfural from sugarcane bagasse was studied in industrial sample and two sugarcane varieties CoJ 85 and CoJ 88. For this the preparation of fine bagasse sample of two varieties similar to industrial sample had been standardized in the laboratory. Then bagasse obtained from sugar industry, sugarcane varieties CoJ 85 and CoJ 88 was treated with different acids (acetic acid, formic acid, hydrochloric acid and sulfuric acid) with variable concentrations (1 and 2 % of each acid) and autoclaved for 30, 60 and 90 minutes with solid-liquid ratio of 1:15 at 1100C temperature and 1.05 kgcm−2 steam pressure for furfural production. The reaction of bagasse with 2 % H2SO4 gave the highest yield of furfural from bagasse of CoJ 88 variety with the time interval of 90 minutes. Furfural can be converted to furfuryl alcohol with flammable hydrogen gas and requires pressure equipment. This thus limits the utility of this process for smaller scale units requiring gram equivalents of furfuryl alcohol that may be required for further applications. Therefore in the present investigation, the inexpensive reagents thiourea dioxide (TUDO), hydroxymethane sulfinic acid (HMS), Zn/HCl and Sn/HCl were tested for the reduction of furfural to furfuryl alcohol. Among all these reagents, Sn/HCl has been found to give the best result where furfural gets reduced to the furfuryl alcohol almost in quantitative yield.

Sucrose accumulation in sugarcane: a potential target for crop improvement

Sugarcane is a highly productive crop plant with the capacity of storing large amounts of sucrose. Sucrose accumulation in the stem of sugarcane has been studied extensively. The initial recognition and characterization of the enzymes involved in sucrose synthesis and cleavage led to the widely accepted models of how sucrose accumulation occurs in the storage tissue. New insights were gained into the physiological role of individual enzyme activities in the process of sucrose accumulation in sugarcane. Studies on cell cultures and on isolated cell fragments initially supported and strengthened these models, but more recent research has revealed their weaknesses. A dynamic model of rapid cycling of sucrose and turnover of sucrose between vacuole, metabolic and apoplastic compartments explains much of the data, but the details of how the cycling is regulated needs to be explored. Genomic research into sucrose metabolism has been based on the premise that cataloging genes expressed in association with the stalk development would ultimately lead to the identification of genes controlling the accumulation of sucrose. Considerable progress has been made in understanding and manipulating the sugarcane genome using biotechnological and cell biology approaches. Thus, the greater understanding of physiology of sucrose accumulation and the sugarcane genome will play a significant role in the future sugarcane improvement programs and will offer new opportunities to develop it as a new-generation industrial crop.

Post harvest quality deterioration in sugarcane under different environmental conditions

Post harvest changes in the juice quality parameters in relation to storage time were investigated in three sugarcane genotypes varying in maturity behaviour viz.CoJ83 (early), CoJ88 (mid) and S70/00(late) under different environmental conditions i.e in the month of November, January and March. A gradual decrease in cane weight, % juice extraction, sucrose (% juice), purity (% juice) and pH with simultaneous increase in TSS%, titrable acidity, dextran, reducing sugars and activities of acid and neutral invertases was found in juice during 12 days of cane storage in all genotypes under all environmental conditions. Irrespective of the genotype and environmental condition, the level of neutral invertase was found to be higher as compared to acid invertase except in genotype S70/00, where higher activity of acid invertase was found as compared to neutral invertase during the month of November. The rate of decrease/increase per day of all the quality parameters on staling was highest during the late crushing period i.e. March than during November and January in all genotypes. More deterioration in quality parameters was found in genotype CoJ83 during March and in genotype S70/00 during November, which may be due to their over mature and immature conditions, respectively, at that time. Hence, the variation in the rate of change in quality parameters during staling may be attributed to the difference in maturity level among genotypes during these three months.

Dextranase production from Paecilomyces lilacinus and its application for dextran removal from sugarcane juice

Dextranase was produced from fungus Paecilomyces lilacinus by submerged fermentation under different cultural conditions viz. pH, incubation temperature, inoculum size and days of incubation for maximum enzyme production. Maximum enzyme production was achieved at pH 6.0 of Mandel media and at temperature 30°C. Inoculum size of 1 × 107 spores/ml was found to be optimum for maximum enzyme production. Enzyme production increased with the increase in days of incubation from 3 to 5 days and then declined thereafter. Dextranase units (from 1 to 15 U/100 ml juice) were exogenously added to sugarcane juice with an aim to optimize dextranase application for removal of dextran from cane juice. Addition of dextranase in juice of cane variety CoS 8436, resulted in relatively less increase in dextran content as compared to control during storage. Whereas, dextran content in untreated juice increased 10 times during 24 h of storage, the increase during this period was only 2.3 times in juice treated with 15 U of dextranase. With the application of 1, 2, 5, 10 and 15 units of dextranase in 100 ml of juice, dextran content was decreased by 15.51, 30.82, 50.20, 68.20 and 73.30 % as compared to the control (with no dextranase added) after 24 h of storage. This study finds application in minimizing the dextran problem in sugar industry.

Partial Purification and Characterization of Acid Invertase from the Fresh and Stale Sugarcane Juice

Soluble acid invertases from the fresh and stale cane juice of variety CoJ83 were purified by fractional precipitation with ammonium sulphate and ion exchange chromatography with DEAE- cellulose. Three isoforms of acid invertase were identified in juice of fresh cane and four isoforms of enzyme were found in juice of stale cane. The isoforms obtained were characterized for their kinetic parameters. Optimum pH and optimum temperature range of isoforms from fresh cane juice were 4.5–5.0 and 35–45°C, however isoforms of invertase from juice of stale cane were having optimum pH of 4.0–4.5 and optimum temperature 40–55°C. Isoforms identified from juice of stale canes were kinetically more efficient in comparison to isoforms identified from juice of fresh canes, as they were having higher Vmax/Km values than isoforms from fresh cane juice. MnCl2 inhibited the soluble acid invertase isoforms of fresh cane completely, but it was unable to inhibit completely the enzyme isoforms of juice of stale cane. ZnCl2, NiCl2, KCl, sodium metasilicate, sodium lauryl sulphate and KMnO4 inhibited the activity of different invertase isoforms in both fresh and stale cane juice, but this inhibition percent was relatively less in stale cane enzyme isoforms as compared to enzyme isoforms from juice of fresh cane. This points to the existence of structural and conformational differences among invertase isoforms in juice of fresh and stale cane.

Pre milling cane preparation for high sugar recovery and reduction of post harvest losses in sugarcane

Pre milling preparation of canes was done by two methods and the effect of these methods on sugar recovery and post harvest quality changes during storage were studied under two environmental conditions i.e February and April. In method one cane was topped by sickle without removal of any internode, while in method II, tops along with 3–4 internodes were removed by sickle/hand. More extraction %, Purity, pol % cane and less reducing sugars were present in fresh canes prepared by method II as compared to method I. Storage of harvested sugarcane prepared by both the methods for six days resulted in decrease in cane weight, extraction %, purity, pol % cane with increase in the invert sugars, activities of enzymes invertases and dextran regardless the envirenmental condition. Percent loss in extraction, purity, pol % cane, percent gain in reducing % brix and their rate of change per day was found to be more in method I than method II. Similarly increase in activities of both acid and neutral invertases as well as dextran were also found higher in method I as compared to method II. Therefore the present study indicated that method II for preparation of canes for milling was superior over the method I since higher sugar recovery and less post harvest deterioration was found in canes prepared by method II as compared to canes prepared by method I.

Advances in bio-nanocomposite materials for food packaging: a review

Purpose The purpose of this paper is to acquaint the readers with recent developments in biopolymer-based food packaging materials like natural biopolymers (such as starches and proteins), synthetic biopolymers (such as poly lactic acid), biopolymer blending and nanocomposites grounded on natural and synthetic biopolymers. This paper is an attempt to draw the readers towards the advantages and attributes of new era polymers to diminish the usage of traditional non-biodegradable polymers. Design/methodology/approach Plastic packaging for food and associated applications is non-biodegradable and uses up valuable and treasured non-renewable petroleum products. With the current focus on researching alternatives to petroleum, research is progressively being channelized towards the development of biodegradable food packaging, thereby reducing adverse impact on the environment. Findings Natural biopolymer-based nanocomposite packaging materials seem to have a scintillating future for a broad range of applications in the food industry, including advanced active food packaging with biofunctional attributes. The present review summarizes the scientific information of various packaging materials along with their attributes, applications and the methods for production. Originality/value This is an apropos review as there has been a recent renewed concern in research studies, both in the industry and academe, for development of new generation biopolymer-based food packaging materials, with possible applications in many areas.

Pectin from Agricultural By-products: Structure, Methods of Extraction, Physiological Benefits and Applications

The production of pectin is considered the most reasonable way of utilization of waste both from an economic and from an ecological point of view. Several methods have been developed for extraction of pectin form fruits/vegetables and their by-products. These various extraction procedures used have reported different percentage yield and quality of pectin depending upon extraction method and conditions. The knowledge of how these factors effect yield and quality of pectin can make it possible to produce polysaccharide for different functions. This article discusses the pectin-structure, types of pectin, plant sources of pectin, different methods of pectin extraction and its physiological benefits and uses.

Effect of packaging films on cell wall hydrolyzing enzymes in relation to shelf life enhancement of tomatoes stored under ambient conditions

The effect of packaging films on post-harvest life span of tomato in relation to their effect on the activities of potential cell wall hydrolyzing enzymes were investigated. Tomato cv. ‘Punjab Upma’ and ‘Punjab Ratta’ picked at pink stage were placed in open trays, high density polyethylene (HDPE)-, low density polyethylene (LDPE)- and polypropylene (PP)-bags and stored under ambient conditions till their edible state. Irrespective of the variety, there was enhancement in the activities of cell wall hydrolyzing enzymes i.e. polygalacturonase, pectin methylesterase, cellulase and β-galactosidase. Further, there was decrease in firmness with increase in storage period. However, less changes were noticed in tomatoes packaged in polythene bags in comparison to those kept in open trays. Tomato cv. ‘Punjab Ratta’ displayed slow increase in the activities of cell wall hydrolases and less decrease in firmness as compared to cv. ‘Punjab Upma’. In both the varieties, LDPE packaging showed slowest changes in enzymatic activities and firmness and were efficient in enhancing the shelf life of tomatoes.