IMPACT OP PROCESS PARAMETERS ON THE NUTRITIONAL VALUE OF CONVECTIVELY DRIED GRAINS

ABSTRACT

The effects of air temperature, air flow rate, residence time and moisture content on selected mechanical, chemical and biological properties of grain were investigated experimentally. It was found that for selection of approprtate conditions for grain drying the two most important foctors are: the moisture content of grain and the drying air temperature. This study suggests the ranges of these parameters depending on the expected utilization of the dried product.     

DIMETHYL SULPHIDE FORMATION IN MALT—EFFECT OF MALTING CONDITIONS

The dimethyl sulphide (DMS) content of kilned malt, and, presumably, the level of precursor in green malt, is significantly affected by malting conditions. Increasing proteolysis favours increased DMS formation in the malt, particularly when induced by higher germination temperatures. The additives gibberellic acid and potassium bromate have opposing effects, some increase being caused by the former and significant reduction being achieved by the latter.     

Time Course for the Development of Enzymes in Barley1

Barley (Hordeum distichon var. Harrington) was steeped, germinated and extracted to observe the order of enzyme development. Different parts of the barley kernel were extracted to observe the order of enzyme development during the malting process. Five enzymes were investigated: carboxypeptidase (EC 3.4.16.1), endo‐β1–3, 1–4‐glucanase (EC 3.2.1.73), endo‐B1‐4‐xylanase (EC 3.2.1.136), arabinofuranosidase (EC 3.2.1.55), and α‐amylase (EC 3.2.1.1). Early development of carboxypepti‐dase, followed by later development of β‐glucanase, then α‐amy‐lase, confirmed earlier reports concerning the sequence of synthesis for these activities. However, xylanase developed during the steeping of barley and early in germination, whereas other authors found this enzyme to develop much later in the malting process. Enzyme activities developed to higher levels in the proximal end of kernels for all enzymes except xylanase, which was evenly distributed throughout the kernel. Enzyme development was tested in sterile barley annuli [embryo‐less cross sections taken through the grain, and thus comprising rings of tissue with husk outermost and starchy endosperm innermost] under four effector conditions. Water controls mirrored the development pattern observed in whole barley kernels. Gibberellic acid (GA₃) promoted higher total enzyme activity and development of all enzymes at the same time. Abscisic acid (ABA) promoted earlier development of late developing enzymes (xylanase, arabinofuranosidase and α‐amylase) and significantly higher levels of xylanase than when treatment was with water alone. Mixtures of GA and ABA showed a non‐exclusive, combined response of higher activity levels and a shifting of the initiation of enzyme development. Treatment with a combination of GA and calcium chloride triggered signifycantly higher carboxy‐peptidase activity and significantly lower xylanase activity as compared to treatment with GA or with GA/ABA mixtures.     

Relative survival of Bacillus subtilis spores loaded on filtering facepiece respirators after five decontamination methods

This study determines the relative survival (RS) of Bacillus subtilis spores loaded on an N95 filtering facepiece respirator (FFR) after decontamination by five methods under worst‐case conditions. Relative survival was obtained by testing after decontamination and after storing the FFRs at 37°C and 95% relative humidity for 24 hours. The decontamination methods involved ethanol, bleach, ultraviolet irradiation (UVA 365 nm, UVC 254 nm), an autoclave, and a traditional electric rice cooker (TERC) that was made in Taiwan. Without decontamination, 59 ± 8% of the loaded spores survived for 24 hours. When 70% ethanol was added to the N95 FFR at a packing density of 0.23, the RS was 73 ± 5% initially and decayed to 22 ± 8% in 24 hours. Relative survival remained above 20% after 20 minutes of UVA irradiation. The other four decontamination measures achieved 99%‐100% biocidal efficacy, as measured immediately after the methods were applied to the test FFRs. Relative survival is a useful parameter for measuring sterilization or degree of disinfection. Bleach, UVC, an autoclave, and a TERC provide better biocidal efficacy than ethanol and UVA. Not only a higher filter quality but also a lower value of RS produced the most decontaminated FFR.     

Structure and antimicrobial activity relationship of quaternary N‐alkyl chitosan derivatives against some plant pathogens

In the present work, quaternary chitosans as water‐soluble compounds were prepared based on three‐step process. Schiff bases were firstly synthesized by the reaction between the amino groups of chitosan with aliphatic aldehydes followed by a reduction with sodium borohydride (NaBH₄) to form N‐(alkyl) chitosans. N,N,N‐(dimethyl alkyl) chitosans were then obtained by a reaction of chitosan containing N‐butyl, N‐pentyl, N‐hexyl, N‐heptyl, and N‐octyl substituents with methyl iodide. The compounds were characterized using IR and NMR spectroscopy. Subsequent experiments were conducted to test their antimicrobial activities against the most economic plant pathogenic bacteria of crown gall disease Agrobacterium tumefaciens, soft mold disease Erwinia carotovora, fungi of grey mold Botrytis cinerea, root rot disease Fusarium oxysporum, and damping off disease Pythium debaryanum. Quaternary chitosans enhanced the antibacterial activity and N,N,N‐(dimethyl pentyl) chitosan was the most active one with Minimum Inhibitory Concentration (MIC) of 750 and 1225 mg/L against A. tumefaciens and E. carotovora, respectively. All quaternized chitosans gave stronger antifungal activities than chitosan where N,N,N‐(dimethyl pentyl) chitosan and N,N,N‐(dimethyl octyl) chitosan were significantly the highest in mycelial growth inhibiation against B. cinerea (EC₅₀ = 908 and 383 mg/L, respectively), F. oxysporum (EC₅₀ = 871 and 812 mg/L, respectively), and P. debaryanum (EC₅₀ = 624 and 440 mg/L, respectively). In addition, spore germination of B. cinerea and F. oxysporum was significantly affected with the compounds at the tested concentrations and the inhibition activity was increased with an increase in the chain length of the alkyl substituent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

DJS水系对米曲霉酶活力提高的研究

研究了DJS水系在酿造酱油制曲中产酶及其活力的影响。试验中与自来水介质进行比较,结果表明:DJS水系能改变米曲霉的孢子数,对其酶活力的提高有显著的影响;在DJS-A介质中的孢子产量虽少于DJS-B介质,而其中的酶活力却较高。     

萌动青稞的研究进展

萌动谷物的研究越来越受到广大学者的关注,特别是萌动青稞。萌动青稞是一种新型的功能性食品,因其具有良好的口感和较高的营养价值而受到人们的喜爱。通过比较青稞萌动前后营养成分的变化、萌动后青稞的生理功效,以及国内外萌动青稞产品的研发现状,综述了国内外萌动青稞研究进展,为我国萌动青稞的开发与利用提供参考。     

不同干燥方式对发芽糙米品质的影响

以香粳99为原料发芽制得发芽糙米,研究了日光干燥、普通热风干燥、微波干燥和真空冷冻干燥对其主要营养成分、加工性能指标及色泽的影响。结果表明,真空冷冻干燥对发芽糙米品质影响最小,其次是微波干燥和普通热风干燥。     

RCS1, a gene involved in controlling cell size in Saccharomyces cerevisiae

Cloning and sequencing of RCS1, Saccharomyces cerevisiae gene whose product seems to be involved in timing the budding event of the cell cycle, is described. A haploid strain in which the 3'-terminal region of the chromosomal copy of the gene has been disrupted produces cells that are, on average, twice the size of cells of the parental strain. The critical size for budding in the mutant is similarly increased, and the disruption mutation is dominant in a diploid heterozygous for the RCS1 gene. Spores from this diploid have a reduced ability to germinate, the effect being more pronounced in the spores carrying the disrupted copy of RCS1. However, disrupted cells recover from alpha-factor treatment equally as well as wild-type cells.     

AMYLOLYSIS OF SORGHUM STARCH AS INFLUENCED BY CULTIVAR,GERMINATION TIME AND GELATINISATION TEMPERATURE

The susceptibility to amylolysis of starches derived from two improved Nigerian sorghum cultivars were evaluated at assay temperatures between 50°C and 75°C. Enhancement of gelatinisation rates at temperatures up to 65°C was not significant inspite of the apparent grain modification due to germination for four days. Greater starch gelatinisation rates (20–22%) were achieved in this study compared to previously reported values, suggesting possible roles for cultivar and malting methods. There was a statistical correlation between starch gelatinisation rates over the temperature range 65°C–75°C and the duration of grain germination (r=0.91 for KSV8 and r=0.5 for SK5912 starches). Gelatinisation rate and temperature were affected significantly by assay pH. The occurrence of two pH related maxima of starch gelatinisation for both cultivera at all temperatures examined indicates the possible presence of two sets of “binding forces” within the starch granules and features of starch retrogradation .