Starchy Materials Research Articles

Adjustable Twin‐Slit Rheometer for Shear Viscosity Measurement of Extruded Complex Starchy Melts

AbstractAn online rheometer with an innovative system of height‐adjustable and independently temperature‐controlled slits was designed to measure the shear viscosity of extruded wheat bran fiber‐containing starchy materials. The range of melt pressures and temperatures, obtained with a die, could be covered by the rheometer. A close ingredient thermomechanical history in the extruder was achieved both with the die and the rheometer, while covering an apparent shear rate from 5 to 30 s–1. Although minor technical problems remained, first rheological data were obtained and showed a pseudoplastic flow behavior for all recipes. The flow curves were fitted by a power law model. Wheat bran fiber addition influenced both the K‐ and n‐values, leading to more shear‐thinning melt behavior and an increase in true shear viscosity. Only a limited effect on these values was found in these preliminary experiments when further increasing the fiber content.

Yeast glucoamylases: molecular-genetic and structural characterization

Glucoamylase is an extracellular enzyme produced mainly by microorganisms. It belongs to the commercially frequently exploited biocatalysts. The major application of glucoamylase is in the starch bioprocessing to produce glucose and in alcoholic fermentations of starchy materials. Filamentous fungi have been the source of glucoamylases for industrial purposes as well as an object of numerous research studies. Some yeasts also secrete a large amount of glucoamylase with biochemical characteristics slightly different from those of filamentous fungi. Modern biotechnological applications require glucoamylases of certain properties optimal for a given process. Novel biocatalysts can be prepared from already existing enzymes using techniques of protein engineering or directed evolution. Tailoring of a commercial glucoamylase requires knowledge, on a molecular level, of structure/function relationships of enzymes originating from various sources and having different catalytic properties. Sequences of the cloned genes, their recombinant expression and the tertiary structure determination of glucoamylase are prerequisite to obtain such information. The presented review focuses on molecular-genetic and structural aspects of yeast glucoamylases, supplemented with the basic biochemical characterization of the given enzymes.

Mechanical and barrier properties of composite films based on rice flour and cellulose fibers

Rice flour is a low-cost starchy material, produced from rice that is broken during processing. Rice flour-based films have promising application on food packaging, because of their environmental appeal and low cost. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of this study was to develop biodegradable films based on rice flour and enhance their properties by reinforcing them with cellulose fibers. In this way, rice flour films with and without fibers were prepared by casting, with glycerol or sorbitol as plasticizer. Their physicochemical, microscopic and mechanical properties were studied. SEM analysis of films revealed compact structures. Films prepared with fibers presented lower water vapor permeabilities if compared with films without fibers. Films containing sorbitol were less permeable to water and more rigid. The incorporation of fibers reinforced mechanically the flour-based films, which presented higher tensile strength, but did not influence their deformation capacity. Therefore, preparing biodegradable films from rice flour is a new alternative of using this raw material. The use of cellulose fibers as reinforcing agent is a viable alternative to improve the properties of rice flour-based films, because they are biodegradable and available at low cost.

Resistant starch: A review of analytical protocols for determining resistant starch and of factors affecting the resistant starch content of foods

Resistant starch (RS) has drawn considerable attention over the last two decades due to its demonstrated and putative positive impacts on health. This has resulted in the development of a variety of analytical protocols for its determination, hence a comprehensive review of methodologies for analyzing resistant starch is warranted. Adding to the complexity, the RS contents of starchy materials vary widely and RS levels are impacted by processing. This review compares commonly used methods for the determination of RS, briefly reviews the process of starch digestion in the human, and discusses the complications and challenges associated with determining RS in foods.

Persistent Traditions in the Face of Natural Disasters: Stemmed and Waisted Stone Tools in Late Holocene New Britain, Papua New Guinea

Studies of the technology and function of small retouched stemmed and waisted stone tools from late Holocene sites in central New Britain provide a powerful means for monitoring the effects of the massive W-K2 volcanic eruption (3480–3150 cal BP), after which pottery occurs in this region for the first time. Use-wear and residue studies show that these tools were used for processing soft starchy plant materials (tubers and wood) and cutting and piercing skin. Despite the catastrophically destructive event, results indicate cultural continuity, most likely by descendants of the original population, rather than population replacement or major cultural change. These results contribute to the ongoing debate about possible migration from Island Southeast Asia c.3400 years ago.

Effect of steam blanching on quality of custard apple pulp

The study on the organoleptic evaluation of custard apple pulp stored up to 70 days was carried out in the Department of Agricultural Process Engineering, C. A. E. T., and M. A. U., Parbhani in the year 2005 - 2006. Statistical analysis and sensory evaluation of the data was carried out and it was observed that effect of storage of custard apple pulp at - 4 and -18°C temperature up to 70 days on scores for sensorial quality of pulp viz appearance, color, flavor, taste, texture and overall acceptability increases from 7.25 - 8.20, 7.3 - 8.0, 6.0 to 7.25, 6.0 - 7.25, 6.25 - 7.0, and 6.30 - 7.5, respectively. The application of heat facilitates molecule damage of constituents of pulp by denaturation of protein, evaporation of volatile constituents and gelatinization of starchy material. This may lead to the changes in sensorial characteristics of the pulp like increased viscosity loss of flavor and taste and change in color. Key words: HDPE - high density polyethylene, COH - carbohydrates, PPO – polyphenoloxidase, TSS -total soluble solids.

Biodegradable films based on rice starch and rice flour

Rice flour is a starchy material with low-cost, because it can be produced from rice that is broken during processing. The aim of this study was to develop biodegradable films based on rice starch and rice flour, and to characterize their physicochemical, microscopic and mechanical properties. Films from rice starch and rice flour were prepared by casting, with glycerol or sorbitol as plasticizer. SEM analysis of starch and flour films revealed compact structures. Rice flour films prepared in the present work have similar mechanical properties to those of starch based films. However, their water vapor permeabilities are two times higher than those of starch based films. Films with sorbitol were less permeable to water and more rigid, while films with glycerol are more plasticized and have poorer water vapor barrier properties. Therefore, preparing edible films from rice flour is a new alternative for using this raw material, which is sometimes much cheaper than commercial starches.

過熱水蒸気処理によるデンプン素材の改質（第2報）：改質デンプン素材の粉体特性と酵素消化性

過熱水蒸気処理によるデンプン素材の改質（第2報）：改質デンプン素材の粉体特性と酵素消化性

Ethanol production by mixed-cultures ofPaenibacillus sp. andZymomonas mobilis using the raw starchy material from sweet potato

The conversion of raw starchy materials from sweet potato into ethanol in a mixed-culture of an amylolytic bacterium, Paenibacillus sp. and different strains of Zymomonas mobilis were studied. Raw starchy material from sweet potato was hydrolyzed by Paenibacillus sp. to glucose, which is directly used by Z. mobilis for ethanol production. A mixed-culture of Z. mobilis ATCC 29191 and Paenibacillus sp. 9 yielded the highest ethanol concentration (6.89 g/l) in cultures of small volumes. The effects of medium pH (the best pH value were between 5.0 and 6.0) and the supplementation of the medium with glucose on ethanol production were also studied. In a large-scale fermentation, the final concentration of ethanol was 6.60 g/l, which corresponds to 23.24% of the theoretical yield of the ethanol from 50.0 g/l of the starch from raw sweet potato after a 120 h fermentation period.

Conversion of cassava starch to trehalose by Saccharomycopsis fibuligera A11 and purification of trehalose

As one of the non-food crops, cassava is widely cultivated in some of the southern provinces of China as a source of starchy material for food and fermentation industry. In this study, cassava starch was used as the substrate for Saccharomycopsis fibuligera A11, a trehalose poor-assimilating mutant isolated from S. fibuligera sdu through chemical mutagenesis, to accumulate trehalose. The results indicated that trehalose accumulation by S. fibuligera A11 was optimal in the medium comprised of 20.0 g/l cassava starch, 20.0 g/l hydrolysate of soybean cake at pH 5.5 and 30 °C for 48 h. At the flask level, trehalose yield was 24.8 g per 100 g of cell dry weight. At the end of 2-l fermentation, trehalose yield was 25.8 g per 100 g of cell dry weight. This is the highest trehalose yield accumulated in the yeast cells reported so far. At the same time, 0.12 g/100 ml of reducing sugar and 0.21 g/100 ml of total sugar were observed in the fermented medium. After isolation and purification, the crystal trehalose was obtained from the culture extract.

Biotechnological production of enantiomeric pure lactic acid from renewable resources: recent achievements, perspectives, and limits

Lactic acid (LA) is an important and versatile chemical that can be produced from renewable resources such as biomass. LA is used in the food, pharmaceutical, and polymers industries and is produced by microorganism fermentation; however, most microorganisms cannot directly utilize biomass such as starchy materials and cellulose. Here, we summarize LA production using several kinds of genetically modified microorganisms, such as LA bacteria, Escherichia coli, Corynebacterium glutamicum, and yeast. Using gene manipulation and metabolic engineering, the yield and optical purity of LA produced from biomass has been significantly improved. In this review, the drawbacks as well as improvements of LA production by fermentation is discussed.

Ethanol Dehydration by Adsorption with Starchy and Cellulosic Materials

Adsorption with starchy and cellulosic materials was evaluated as an energy efficient technology for ethanol dehydration. Corn (Zea mays), upright elephant ear (Alocasia macrorrhiza), cassava (Manihot esculenta), and sugar cane bagasse (Saccharum), were used as sources of starch and cellulosic fibers and further used as adsorbents for water removal. Enzymes (α-amylase and cellulase for starch and cellulose, respectively) were evaluated as modifying agents with the aim of increasing water adsorption capacity. Native and enzyme-treated materials were examined with SEM, XRD, and BET analysis to determine the hydrolysis influence on structure and superficial area. Partial hydrolysis was obtained under operation conditions evaluated, as was shown by the SEM micrographs. Crystallinity increased with the enzymatic hydrolysis for all materials. For all materials, superficial area was not increased with enzymatic hydrolysis but water adsorption capacity was improved reaching an anhydrous product with enzyme-treated materials. Water adsorption capacity ranges from 4 to 19 g/ 100 g adsorbent were found for evaluated materials. Corn starch had the highest water adsorption capacity (19 g/ 100 g ads) while upright elephant ear starch presented the lowest (4.2 g/ 100 g ads). Tested materials showed affinity with water for both native and enzyme-treated cases. This allowed water to adsorb from the feed for obtaining anhydrous ethanol. It was suggested that water adsorption capacity was increased because of the more exposed hydroxyl groups from the polymeric structures evaluated (starch and cellulose). Applicability of these materials was oriented to small scale ethanol production plants in developing countries where rural areas are the objective and small productions are expected.

Influence of variety and growth environment on β-amylase activity of flour from sweet potato ( Ipomea batatas)

In order to select a suitable Ghanaian variety of sweet potato as enzyme source for the production of glucose syrups, four varieties of sweet potatoes – Sauti, Santom pona, Faara and Okumkom – cultivated in two different agro-ecological zones of Ghana were evaluated for β-amylase activity. Faara and Okumkom varieties harvested at 5 months maturity from the forest zone showed the highest β-amylase activity and consequently the most suitable potential enzyme source for the hydrolysis of starchy materials in glucose syrup production. Enhancing β-amylase levels in sweet potatoes has potential cost efficiency advantages in glucose syrup production.

Continuous Ethanol Production from Cassava Through Simultaneous Saccharification and Fermentation by Self-Flocculating Yeast Saccharomyces Cerevisiae CHFY0321

In this study, a fermentor consisting of four linked stirred towers that can be used for simultaneous saccharification and fermentation (SSF) and for the accumulation of cell mass was applied to the continuous production of ethanol using cassava as the starchy material. For the continuous process with SSF, the pretreated cassava liquor and saccharification enzyme at total sugar concentrations of 175 g/L and 195 g/L were continuously fed to the fermentor with dilution rates of 0.014, 0.021, 0.031, 0.042, and 0.05 h(-1). Considering the maximum saccharification time, the highest volumetric productivity and ethanol yield were observed at a dilution rate of 0.042 h(-1). At dilution rates in the range of 0.014 h(-1) to 0.042 h(-1), high production rates were observed, and the yeast in the first to fourth fermentor showed long-term stability for 2 months with good performance. Under the optimal culture conditions with a feed sugar concentration of 195 g/L and dilution rate of 0.042 h(-1), the ethanol volumetric productivity and ethanol yield were 3.58 g/L x h and 86.2%, respectively. The cell concentrations in the first to fourth stirred tower fermentors were 74.3, 71.5, 71.2, and 70.1 g dry cell/L, respectively. The self-flocculating yeast, Saccharomyces cerevisiae CHFY0321, developed by our group showed excellent fermentation results under continuous ethanol production.

Development of strains of the thermotolerant yeast Hansenula polymorpha capable of alcoholic fermentation of starch and xylan

The thermotolerant yeast Hansenula polymorpha ferments glucose and xylose to ethanol at high temperatures. However, H. polymorpha cannot utilize starchy materials or xylans. Heterologous amylolytic and xylanolytic enzymes have to be expressed in this yeast to provide for utilization and growth on starch and xylan. Genes SWA2 and GAM1 from the yeast Schwanniomyces occidentalis, encoding α-amylase and glucoamylase, respectively, were expressed in H. polymorpha. The expression was achieved by integration of the SWA2 and GAM1 genes under the strong constitutive promoter of the H. polymorpha glyceraldehyde-3-phosphate dehydrogenase gene ( HpGAP) into H. polymorpha genome. Resulting transformants acquired the ability to grow on a minimal medium containing soluble starch as a sole carbon source. Ethanol production at high-temperature fermentation from starch by the recombinant strains was up to 10 g/L. The XYN2 gene encoding endoxylanase of the fungus Trichoderma reseei was expressed in H. polymorpha. Co-expression of xlnD gene coding for β-xylosidase of the fungus Aspergillus niger and the XYN2 gene in H. polymorpha was achieved by integration of these genes under control of the HpGAP promoter. Resulting transformants were capable of growth and alcoholic fermentation on a minimal medium supplemented with birchwood xylan as a sole carbon source at 48 °C.

Evaluación de la sacarificación de yuca mediante el proceso convencional y el proceso low-energy, para su posterior determinación de la cinética de reacción

En este trabajo se evaluaron los ensayos para la obtención de azúcares fermentables a partir de materias amiláceas, en este caso particular yuca, los cuales comprendieron el seguimiento de la reacción de hidrólisis enzimática para la posterior determinación de la cinética de reacción (formación de producto en función del tiempo). En una primera etapa se consideró el proceso convencional que consta de licuefacción y sacarificación, a cargo de una alfa-amilasa y una gluco-amilasa comerciales respectivamente. Yen una segunda etapa la acción bifuncional de una única enzima comercial, analizándose por separado las dos partes constitutivas de la yuca: el parénquima interno y el parénquima externo. La materia prima se caracterizó en cuanto a su composición, porcentaje de humedad, proteína y por último contenido de almidón enbase seca.

ARTIFICIAL CELL STUDIES IN SIMULATED APPLE AND POTATO STARCH CELL COMPLEX DURING OSMOTIC DEHYDRATION

ABSTRACT Visking tubing was employed as an artificial cell system to investigate the behavior of water in simulated apple and potato starch cell complex during osmotic dehydration. The study involved a factorial experimental design at three levels of temperature (32.2, 40 and 55C) and five levels of solute concentration solutions (four sucrose concentrations: 40, 50, 60 and 70%; one sodium chloride concentration: 0.5%). A time period of 0–3 h was implemented with 30‐min sampling period for every treatment. Three phases of a sharp decrease in the initial weight of the visking tubing in the first 30 min were observed for all temperatures and solute concentrations. In all the treatments, there was an incremental increase in water loss with increased temperature and sucrose and salt concentrations. Water loss was higher for simulated apple and 1% potato starch solutions compared with 15% potato starch solution. Starch in the visking tubing competed for the removal of water during osmotic dehydration. The amount of starch contributed to the differences in the rate of water loss in the visking tubing. PRACTICAL APPLICATIONSIn order to better understand the behavior of water in simulated apple and potato starch cell complex during osmotic dehydration of plant materials, the Visking tubing was used as an artificial cell in simulating biological membranes. Simulated apple and potato starch was studied as representatives of cellulosic and starchy plant materials, respectively. Notably, there was antagonistic effect between starch and salt solutions, starch and sugar solutions similar to sugar and salt solutions as a result of differences in their molecular weights. This study is industrial applicable to achieve efficient osmotic dehydration processes for plant materials that are cellulosic or starchy in nature.

Hydrothermal processing of rice husks: effects of severity on product distribution

AbstractBACKGROUND: Treatment in aqueous media (hydrothermal or autohydrolysis reactions) is an environmentally friendly technology for fractionating lignocellulosic materials. Rice husks were subjected to hydrothermal processing under a variety of operational conditions to cause the selective breakdown of xylan chains, in order to assess the effects of reaction severity on the distribution of reaction products.RESULTS: The effects of severity (measured by the severity factor, R0) on the concentrations of the major autohydrolysis products (monosaccharides, xylo‐ and glucooligosaccharides, xylooligosaccharide substituents, acetic acid, acid‐soluble lignin and elemental nitrogen) were assessed. The interrelationship between the severity of treatment and molecular weight distribution was established by high‐performance size‐exclusion chromatography. Selected samples were subjected to refining treatments as ethyl acetate extraction and ion exchange for refining purposes, and the concentrates were assayed by high‐performance anion‐exchange chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry.CONCLUSIONS The protein equivalent of the products present in liquors accounted for 43 to 51% of the protein present in the raw rice husks. The concentrations of glucose (derived from starchy material) and arabinose (split from the xylan backbone) were fairly constant with severity. Even in treatments at low severity, high molecular weight compounds derived from xylan accounted for a limited part of the stoichiometric amount. Operating under harsh conditions, about 50% of the total xylan‐derived compounds corresponded to fractions with a degree of polymerization (DP) < 9. After refining, saccharides accounted for more than 90% of the non‐volatile components of the sample. The refined products showed a series of xylose oligomers up to about DP 13, and a series of acetylated xylose oligomers up to about DP 15. Copyright © 2008 Society of Chemical Industry

Using a commercial DNA extraction kit to obtain RNA for RT‐PCR from starchy rice endosperm

The extraction of RNA from a starchy plant material, such as many common food grains, is difficult, and especially so from the mature endosperm of rice. Most commercial RNA kits are not suitable for starchy materials. Traditional RNA extraction procedures, in addition to being laborious and time consuming, leave hazardous organic wastes that result in expensive disposal costs. Interestingly, the numerous commercial DNA isolation kits now available often include directions for eliminating co-isolated RNA. This indicated an approach to obtain the generally unwanted RNA by-product by treating the total extraction product to intentionally retain RNA. A method was developed by which a two-step DNase procedure was applied to the product of the Cartagen Food DNA extraction kit that eliminated the DNA but left the co-extracted RNA. This modified procedure was compared with several other commercial and standard methods that are promoted as being able to work under high polysaccharide conditions. Successful extraction was determined by the production and amplification of cDNA by RT-PCR of actin. Extraction was successful from milled rice, as well as from cornmeal and wheat flour. The modification provides an RNA extraction method that is quick, easy, and inexpensive, and also eliminates the production of hazardous wastes.

Coskata's new process could threaten bioethanol prospects of Danisco and Novozymes

Production of ethanol (bioethanol) from biomass is one way to reduce both consumption of crude oil and environmental pollution. Bioethanol is appropriate for the mixed fuel in the gasoline engine because of its high octane number, and its low cetane number and high heat of vaporization impede self-ignition in the diesel engine. So, ignition improver, glow-plug, surface ignition, and pilot injection are applied to promote self-ignition by using diesel-bioethanol-blended fuel. Disadvantages of bioethanol include its lower energy density than gasoline, its corrosiveness, low flame luminosity, lower vapor pressure (making cold starts difficult), miscibility with water, and toxicity to ecosystems. Bioethanol can be produced from cellulosic feedstocks. One major problem with bioethanol production is the availability of raw materials for the production. The availability of feedstocks for bioethanol can vary considerably from season to season and depends on geographic locations. Lignocellulosic biomass is the most promising feedstock considering its great availability and low cost, but the large-scale commercial production of fuel bioethanol from lignocellulosic materials has still not been implemented. Conversion technologies for producing bioethanol from cellulosic biomass resources such as forest materials, agricultural residues and urban wastes are under development and have not yet been demonstrated commercially. For designing fuel bioethanol production processes, assessment of utilization of different feedstocks (i.e. sucrose containing, starchy materials, lignocellulosic biomass) is required considering the big share of raw materials in bioethanol costs. In this work a review of the biological and thermochemical methods that could be used to produce bioethanol is made and an analysis of its global production trends is carried out.