摘要:

AbstractStarch was isolated from quinoa (Chenopodium quinoa) for a study of physico‐chemical properties, functional characteristics and a comparison with starches from wheat, barley, wild rice, amaranth and potatoes. Quinoa starch granules range in size from 0.6 to 2.0 μm and are found within the cells of the seed as single entities or as compound structures of spherical or oblong aggregates. Quinoa starch exhibited a higher Amylograph viscosity, a greater waterbinding capacity and a greater swelling power compared to wheat‐ or barley starch. The gelatinization temperature range of quinoa starch was slightly higher than that of wheat‐ or barley starch. Amylose content was lower. As a thickening agent for fillings, quinoa starch performed better than other starches in the study. However, breads and cakes baked with quinoa starch were of poor quality. Volumes were lower, the grain non‐uniform with thick cell walls and the texture dense and compact. The overall performance of quinoa starch in baked goods was similar to that of other non‐cereal starches (amaranth‐ and po

ISSN:0038-9056    

DOI:10.1002/star.19900420302

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractFür die pflanzenzüchterische Nutzung von Amylosemutanten ist eine Methode, die den Amylosegehalt eines Einzelkorns messen kann, von Bedeutung. In der vorliegenden Arbeit wird eine potentiometrische Titration zur Amylosebestimmung an einem halben, reifen Gerstenkorn beschrieben und die Auswertung der Titrationskurven diskutiert. Mit Hilfe der dargestellten Methode gelingt eine Einteilung verschiedener Gerstensorten und ‐linien in Genotypen mit unterschiedlichem Amylosegeh

ISSN:0038-9056    

DOI:10.1002/star.19900420303

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe Rapid Visco‐Analyzer (RVA) was used to study the effects of sucrose ester (SE) emulsifiers and a propylene glycol ester (PGE) emulsifier on starch cooking properties. Maize, tapioca and wheat starches were affected to different degrees by F‐160 SE with a hydrophil‐lipophil balance (HLB) of 15. Up to a concentration of 0.05 parts emulsifier to 1 part starch, the F‐160 SE increased peak viscosity, time to peak and maximum setback viscosity of the starches. These data suggested that the SE functioned by forming a clathrate complex with the starch molecules. When cooking properties of maize starch were studied in the presence of SEs with HLB 6, 11 and 15, the effects of the SE did not appear to be directly related to HLB. The PGE did not appear to form a clathrate complex with wheat starch, as indicated by a decrease in peak viscosity and time to peak. Cooking properties of the starches were also measured in the presence of sugars (dextrose, sucrose, corn syrup solids and polydextrose) at a level of 2 parts sugar to 1 part starch, plus emulsifiers at a ratio of 0.02:1. Peak viscosity, time to peak and maximum setback viscosity were affected synergistically in the presence of both sugar and emulsifier as compared to additive effects of the two ingredients acting alone. Although reaction mechanisms could not be defined from the data obtained, the RVA proved useful for quickly demonstrating the effects of multiple ingredients on starch cooking pro

ISSN:0038-9056    

DOI:10.1002/star.19900420304

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractMorphological changes of starch granules from potato and corn were studied by scanning electron microscopy after they were heated progressively to different temperatures in an excess of water. A honeycomb‐like structure was observed within the granules at the gelatinization temperature. It was believed that formation of this structure caused the irreversible, profound swelling and loss of the polarization crosses. Higher temperatures resulted in further swelling and melting which led to strong deformation of the granules, and ultimately the molten granules connected with each other to form a spongelike structur

ISSN:0038-9056    

DOI:10.1002/star.19900420305

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractRetrogradation rate and extent were determined by differential scanning calorimetry and rheology measurements on 40% dry matter gels made from pea, modified waxy maize, rice, waxy rice, wheat, manioc, potato and microwaved irradiated potato starches. As a result, each starch retrogrades differently, depending also on the measurement technique. Nevertheless, potato and pea starches seem to be the most sensitive and the waxy and modified waxy types are the least sensitive to retrogradation.

ISSN:0038-9056    

DOI:10.1002/star.19900420306

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA. paniculatasor Rajgeera has been shown to contain 50–60% of waxy starch, having an extremely small granule size of 1–2 μm, and higher paste viscosity than corn starch. Studies on utilisation of Rajgeera starch for custard preparations showed it to be unsuitable for such purpose because of interactions among the various ingredients used in the formula

ISSN:0038-9056    

DOI:10.1002/star.19900420307

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractUsing maltohexaose G6as a substrate, a convenient analytical method for amylase‐catalyzed hydrolytic reaction was developed by application of an enzymatic assay‐kit (glucose oxidase‐peroxidase) to measurement of glucose, produced on the reaction: G6→G5+ G. The initial velocity was confirmed to be proportional to the initial concentration of amylase, examined, ∼ 100 μm. The new method was found in a good correlation with theNelsonandSomogyimethod. Rate assay was also examined: The initial velocity is proportional to the enzyme concentration, ∼ 30 μm. Hence, this enzymatic assay method is recognized to be convenient and useful for the measurement

ISSN:0038-9056    

DOI:10.1002/star.19900420308

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractWhen starch was treated with KMnO4solution, MnO2was deposited overall the starch. The amount of MnO2deposited relied on the KMnO4concentration. Subjecting the MnO2‐containing starch to a solution consisting of monomer (methacrylic acid, MAA) and acid (citric, tartaric, oxalic or sulphuric acid) resulted in formation of poly(MAA)‐starch graft copolymer. The magnitude of grafting, expressed as meq. ‐COOH/100 g starch, was determined by amount of MnO2deposited, MAA concentration, temperature and duration of polymerization as well as kind and concentration of the acid. Incorporation of cations such as Fe+3, Cu+2and Li+1had a significant effect on grafting. The highest extent and rate of grafting were obtained with citric acid and the least with sulphuric acid; tartaric acid stood in‐mid‐way position. The magnitude of grafting increased as the acid concentration increased till a certain concentration beyond which grafting levelled off. Similar trend was observed when the magnitude of grafting was related to the amount of MnO2deposited. The extent and rate of grafting increased by raising the polymerization temperature from 30° to 50°C then decreased by raising the temperature further from 60° to 70°C. On the other hand, grafting enhanced significantly by addition of Fe+3, Cu+2or Li+1and followed the order Fe+3>Cu+2>Li+1. A tentative mechanism for grafting of starch with MAA using MnO2‐acid system

ISSN:0038-9056    

DOI:10.1002/star.19900420309

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractFructose undergoes dehydration reactions to form difructose dianhydrides during crystallization. Difructose dianhydrides can be incorporated into fructose crystals and inhibit the crystal growth. In this study, the kinetics of difructose dianhydrides formation under industrial crystallization conditions were investigated. Four difructose dianhydrides were detected by HPLC analysis. An empirical second‐order irreversible kinetic model was proposed for the reaction. The extent of reaction increased with increasing temperature and decreasing pH value of the solution. The amount of two of the difructose dianhydrides stopped increasing when the fructose concentration was about 70% or less. On the other hand, the formation of all dimers were retarded when the initial fructose concentration was higher than 80

ISSN:0038-9056    

DOI:10.1002/star.19900420310

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900420311

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY