Pradyuman Kumar

Adsorption and reuse of cellulases during saccharification of cellulosic materials

Abstract Adsorption characteristics of cellulases onto cellulosic materials such as potato pulp (waste from potato starch industry) were studied and compared with the adsorption onto Avicel (microcrystalline cellulose). We investigated the adsorption of cellulases as a means of determining the minimal enzyme loading for hydrolysis and recycling of enzymes. Most of the enzymes were rapidly adsorbed onto the substrate within the first 10 min of contact at 30°C. Temperature had no significant influence on the adsorption behaviour of cellulases in the range of 10–30°C. The amount of adsorbed activities increased with increasing enzyme concentration up to a loading of 50 units per g substrate. The enzyme loading at which saturation of substrate occurs correlated with the optimum loading for hydrolysis, thus indicating that the adsorption process controls the rate of hydrolysis. It was observed that more than 40% of the cellulase adsorbed onto the unhydrolyzed residue after hydrolysis, whereas the rest of the enzyme remained in the hydrolysate. Some simple methods were examined for effective recovery and recycling of these enzymes.

Fusarium oxysporum: Status in Bioethanol Production

Fermentation of lignocellulosic materials to ethanol and other solvents provides an alternative way of treating wastes and producing chemical feedstocks and fuel additives. Considerable efforts have been made in past 10 years to improve the process based on lignocellulosic biomass and hydrolysate that contains a complex mixture of sugars, decomposition products of sugars, and sometimes the inhibitory levels of soluble lignin. Despite the relative abundance of D-xylose in crop and forest residues it has not been found efficiently fermentable by most of the microorganisms. Recent research has revealed that D-xylose may be fermented to ethanol and organic acids. Recently, several strains of Fusarium oxysporum have been found to have potential for converting not only D-xylose, but also cellulose to ethanol in a one-step process. Distinguishing features of F. oxysporum for ethanol production in comparison to other organisms are identified. These include the advantage of in situ cellulase production and cellulose fermentation, pentose fermentation, and the tolerance of sugars and ethanol. The main disadvantage is the slow conversion rate when compared with yeast.

Formation of acetic acid from cellulosic substrates byFusarium oxysporum

SummaryFour strains of Fusarium oxysporum and a strain of Monilia brunnae were screened for their ability to convert cellulosic substrates into ethanol/acetic acid. These strains were found to utilize cellulose and produce extracellular cellulases. However, only F. oxysporum 841 was found to convert glucose, xylose, and cellulose into ethanol and acetic acid as major end-products under microaerobic conditions. Acetic acid at a level of 4.7 g/l resulted in a single-step process on potato pulp medium, indicating the potential of the strain for converting cellulosic substrates into acetic acid.

Fed-Batch culture for the direct conversion of cellulosic substrates to acetic acid/ethanol by Fusarium oxysporum

The production of acetic acid/ethanol and hydrolytic enzymes from potato waste ( cellulosic waste from potato starch industries ) by Fusarium oxysporum 841 was improved considerably by using fed-batch culture. In this, two types of feed policies were adopted consisting of different substrate concentrations and feeding times. In fed-batch culture, the enzymes tested, namely avicelase, CMCase, cellobiase and xylanase, showed significant improvements over batch fermentations with regard to enzyme titres and productivities. The maximum concentration, yield and productivity of acetic acid were 22·5 g litre−1, 0·38 g (g substrate)−1 and 0·09 g litre−1 h−1, respectively, and these values for ethanol were 5·7 g litre−1, 0·1 g (g substrate)−1 and 0·03 g litre−1 h−1, respectively.

Comparative efficiency of maltodextrin and protein in the production of spray-dried tamarind pulp powder

ABSTRACT The potential of maltodextrin (DE 20) and soya protein isolate (SPI) in spray drying of tamarind pulp was compared. Powder recovery was zero when the tamarind pulp was spray dried alone. A greater amount of maltodextrin (MD; 55%) was required for successful spray drying of tamarind pulp, whereas a small amount of SPI (20%) was needed for the same purpose. The study revealed that the mechanism for the increase in product recovery with the addition of MD is due to the increase in overall glass transition temperature of tamarind pulp powder. However, using SPI, preferential migration of the protein to the surface of droplets/particles resulting in the formation of a glassy skin was responsible for a reduction in stickiness between the particles and dryer wall and hence increased the powder recovery. The potential of SPI in reducing powder hygroscopicity was almost comparable to that of MD, confirming its efficiency as a drying aid. Tamarind pulp powders produced with SPI had a larger particle size with a wrinkled particle surface morphology and high flowability compared to powders produced with MD. The study showed the excellent potential of SPI as a drying aid in production of quality tamarind pulp powder.

Effect of Soya Protein Isolate as a Complementary Drying Aid of Maltodextrin on Spray Drying of Tamarind Pulp

ABSTRACT The present study aimed to investigate the effect of adding soya protein isolate (SPI) as a complementary drying aid of maltodextrin (MD) on spray drying of tamarind pulp. Tamarind pulp powders were prepared by spray drying of tamarind pulp, adding 0, 5, 10, 15, and 20% of SPI together with maltodextrin as the drying aids. The results showed that the addition of SPI resulted in a significant increase in powder recovery from 9.35 to 70.04%, thereby reducing the requirement of higher levels of maltodextrin for the production of quality tamarind pulp powder. The powders were evaluated for moisture content, bulk density, particle size, morphological characteristics, cohesiveness, and glass transition temperature. With the addition of SPI in the feed material, the powder samples showed a significant variation in their properties. Addition of SPI decreased the cohesion index of the powders from 14.21 to 9.29 mm, thereby increasing the flowability of the powders. Surface morphology of the powders showed that the addition of SPI resulted in an indented and wrinkled particle surface, a characteristic feature of powders produced with protein as the drying aid.

Optimization of spray drying conditions for production of quality pomegranate juice powder

Abstract The present study was aimed to optimize the spray drying operating parameters for the production of quality pomegranate juice powder using response surface methodology. The spray drying operating conditions including inlet air temperature (170–190°C), feed flow rate (18–30 mL/min), and blower speed varied (2,000–2,400 rpm) were used as independent variables. The responses evaluated were ascorbic acid content, anthocyanin content, moisture content, hygroscopicity, and water solubility index. Statistical analysis showed that among the independent variables, inlet air temperature showed greater effect on all the investigated responses. The derived optimum conditions were used for the powder production to check the validity of the quadratic model. Small deviations were observed between the experimental values and the predicted ones and the values were within the acceptable limits. The results showed that the optimum spray drying operating conditions for the production of pomegranate juice powder with optimum quality were 171°C inlet temperature, 30 mL/min feed flow rate, and 2,400 rpm blower speed. Under these optimum conditions, quality pomegranate juice powder with desirable properties of high content of vitamin C and anthocyanin, low moisture content, low hygroscopicity, and high solubility could be produced.

Maize—A potential source of human nutrition and health: A review

Abstract Maize or corn (Zea mays L.) is an important cereal crop of the world. It is a source of nutrition as well as phytochemical compounds. Phytochemicals play an important role in preventing chronic diseases. It contains various major phytochemicals such as carotenoids, phenolic compounds, and phytosterols. It is believed to have potential anti-HIV activity due to the presence of Galanthus nivalis agglutinin (GNA) lectin or GNA-maize. A tablespoon of maize oil satisfies the requirements for essential fatty acids for a healthy child or adult. Decoction of maize silk, roots, leaves, and cob are used for bladder problems, nausea, vomiting, and stomach complaints. Zein an alcohol-soluble prolamine found in maize endosperm has unique novel applications in pharmaceutical and nutraceutical areas. Resistant starch (RS) from maize reduces the risk of cecal cancer, atherosclerosis, and obesity-related complications. This review presents a detailed view on the nutritional and potential health benefits of maize.

Stickiness Problem Associated with Spray Drying of Sugar and Acid Rich Foods: A Mini Review

Spray drying is the most common technique used in food industries for large scale production of milk powders, fruit juice powders, encapsulated flavor etc. However spray drying of sugar and acid rich food materials is associated with stickiness problem. On spray drying of these food materials, the powder particles stick to one another and to the walls of the dryer, leading to the operational problems and low product yield. The sticky behavior is attributed to presence of low molecular weight sugars and organic acids which have low glass transition temperature. In order to achieve successful drying, various methods like addition of high molecular weight drying aids to increase glass transition temperature of feed mixture, use of low humidity and low temperature conditions, scrapping of dryer surfaces, cooling of dryer wall by using dehumidified air and surface modification by proteins to encapsulate sugars can be used.

Optimization and functionality of millet supplemented pasta

Millets are having superior nutritional qualities and health benefits; hence they can be used for supplementation of pasta. Pasta was prepared using composite flour (CF) of durum wheat semolina (96%) and carrot pomace (4%) supplemented with finger millet flour (FMF, 0-20g), pearl millet flour (PMF, 0-30g) and carboxy methyl cellulose (CMC, 2-4g). Second order polynomial described the effect of FMF, PMF and CMC on lightness, firmness, gruel loss and overall acceptability of extruded pasta products. Results indicate that an increasing proportion of finger and pearl millet flour had signed (p≤0.05) negative effect on lightness, firmness, gruel loss and overall acceptability. However, CMC addition showed significant (p≤0. 05) positive effect on firmness, overall acceptability and negative effect on gruel loss of cooked pasta samples. Numeric optimization results showed that optimum values for extruded pasta were 20g FMF, 12g PMF and 4g CMC per 100g of CF and 34ml water with 0.981 desirability. The pasta developed is nutritionally rich as it contains protein (10.16g), fat (6g), dietary fiber (16.71g), calcium (4.23mg), iron (3.99mg) and zinc (1.682mg) per 100g.