糖和亲水胶体对葛根淀粉流变学特性影响的研究

糖和亲水胶体对葛根淀粉流变学特性影响的研究结果表明，随糖和亲水胶体浓度的增加，葛根淀粉溶液的粘度逐渐增加，并且有协同增粘效应。在糖和亲水胶体浓度低时，随糖和亲水胶体浓度增加，葛根淀粉的凝胶强度和剪切强度也逐渐增加，而当糖和亲水胶体浓度进一步增加时，其凝胶强度和剪切强度反而减少。     

Online measurement of water content in candidate reference materials by acousto-optical tuneable filter near-infrared spectrometry (AOTF-NIR) using pork meat calibrants controlled by Karl Fischer titration

Certified reference materials (CRMs) are prepared from a wide variety of matrices. Water removal is an excellent way of achieving increased matrix lifetime and hence CRM stability. High-speed acousto-optical tuneable filter near-infrared spectrometry (AOTF-NIR) has been implemented for measurement of water content in powder matrix reference materials in amber glass vials. Almost 50,000 spectra were collected from 1300 to 2100 nm with a 2 nm increment for powders of meat, rye grass, potato, cotton seed and sugar beet. The AOTF-NIR instrument was placed in a capping machine, with a measurement frequency of 10–15 vials/min and a trigger signal for reproducible collection of spectra. The calibrants comprised 19 pork meat powder samples equilibrated with different hygrostatic solutions or subjected to oven drying to achieve different water concentrations. Mixtures of powders with different water content were also prepared in order to obtain a calibration range from 0.5 to 8.3% water (m/m). All calibration samples were measured by volumetric Karl Fischer titration (V-KFT), accredited under ISO 17025. The calibrants were then measured by AOTF-NIR together with the samples. Multiplicative scatter correction (MSC) was applied to the absorbance spectra in order to correct for the scattering of light in the different powders and scattering effects from the vials. A partial least squares regression model (PLS) based on two principal components was created and applied for prediction of water content in the samples with a standard error of 0.5% water (m/m).     

提高酿酒葡萄糖份含量的分子生物学机制

果实品质在很大程度上取决于果实内所含糖的种类和数量,要提高果实的品质需深入了解果实内糖积累的机制,抓住关键的环节人为加以调控或在遗传特性上加以改良.本文综述了酿酒葡萄的糖代谢生理生化及分子生物学机制,并提出了国内外最新研究动态.     

妙破压榨辊壳

介绍了一种巧妙地利用力的作用，不需动用机械设备，便能轻而易举地破裂压榨辊壳，把轴取出的方法。实践证明，用此法比用钻床钻孔或用龙门刨床刨壳的方法，都能提高工效和减少费用。     

磁化水对甜菜种子萌发期和幼苗期体内几种酶活性的影响

磁化水可提高甜菜种子萌发期和幼苗期体内淀粉酶活性、过氧化氢酶活性、超氧化物歧化酶活性。磁化水可提高甜菜种子的发芽势。     

黑龙江省甜菜按糖收购计价标准的研究

13年糖分资料数理分析结果表明，相邻积温带间甜菜含糖率差异高度显著，均达到1％显著水准。将黑龙江省划分为3个甜菜按糖计价区域，其糖分标准分别为14.9％～15．5％、16．1％～16．7％和16．8％～17．4％。甜菜基本价为310元／t，超糖分标准每增加0．1°S加价2．5～28元／t，低于糖分标准每降低0．1°S减价2．5～3．0元／t。     

A comparison of sugar-accumulating patterns and relative compositions in developing fruits of two oriental melon varieties as determined by HPLC

Sugar-accumulating patterns and compositions were compared between two oriental melon varieties, “Huangjingua” (Cucumis melo var. makuwa Makino) and “Yuegua” (Cucumis melo var. conomon Makino). Sucrose and reducing sugars were measured in different mesocarp tissues of developing fruits. They were all characterized by enhanced accumulation of glucose and fructose during early fruit development with almost no sucrose detectable. However, a transition of sucrose enhancement was accompanied by fruit maturing in the variety “Huangjingua”, while no such transition was observed in the variety “Yuegua” that merely had a sucrose content throughout development. In “Huangjingua”, both sucrose and total sugar gradients were observed, ascending from mesocarp adjacent to pedicle, middle part of mesocarp, and up to mesocarp adjacent to umbilicus. However, no obvious gradient in sucrose accumulation was seen among three mesocarp tissues examined. In terms of sweetness index, fructose is the chief contributor to sugar accumulation in both varieties. Also, the melon variety “Huangjingua” could be comparatively considered as a high-sucrose accumulator and “Yuegua” a minor-sucrose accumulator.     

Structure-composition relationships of the Traditional Balsamic Vinegar close to jamming transition

The Traditional Balsamic Vinegar of Modena (TBVM), an Italian valuable specialty produced from cooked grape must becomes viscous through a long-ageing process. TBVM may undergo jamming transition which causes its depreciation. A liquid and jammed TBVM were investigated for their microstructure and elemental composition by coupling two non-destructive techniques, i.e. Environmental Scanning Electronic Microscopy (ESEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The same samples were also analyzed for their molecular size distribution by Size Exclusion Chromatography (SEC) and their shear viscosity with a stress-controlled rheometer. TBVM in the jammed state behaved as a pseudoplastic fluid due to the presence of nitrogen-free polymers with a molecular size dispersion lower than a liquid TBVM, the latest showed the Newtonian flow behavior. TBVM solid particles detected close to jamming transition showed a C/O ratio of 2.5 (liquid TBVM) and 3.7 (jammed TBVM), thus much higher than the main TBVM constituents (glucose, fructose and acetic acid). The Fe and Mg content was higher and pH was lower in the jammed TBVM. It was hypothesized that jamming transition in TBVM was the result of the unbalance between two time-dependent phenomena, i.e. the increase of the bulk viscosity and the structure relaxation of nitrogen-free polymers.     

Sugar reduction without compromising sensory perception. An impossible dream?

ABSTRACT

Sugar reduction is a major technical challenge for the food industry to address in response to public health concerns regarding the amount of added sugars in foods. This paper reviews sweet taste perception, sensory methods to evaluate sugar reduction and the merits of different techniques available to reduce sugar content. The use of sugar substitutes (non-nutritive sweeteners, sugar alcohols, and fibres) can achieve the greatest magnitude of sugar and energy reduction, however bitter side tastes and varying temporal sweet profiles are common issues. The use of multisensory integration principles (particularly aroma) can be an effective approach to reduce sugar content, however the magnitude of sugar reduction is small. Innovation in food structure (modifying the sucrose distribution, serum release and fracture mechanics) offers a new way to reduce sugar without significant changes in food composition, however may be difficult to implement in food produced on a large scale. Gradual sugar reduction presents difficulties for food companies from a sales perspective if acceptability is compromised. Ultimately, a holistic approach where food manufacturers integrate a range of these techniques is likely to provide the best progress. However, substantial reduction of sugar in processed foods without compromising sensory properties may be an impossible dream.     

Sweetness and texture perceptions in structured gelatin gels with embedded sugar rich domains

Layered and homogeneous gelatin gels with controlled rheological properties were compared for their sensory characteristics, specifically sweetness, hardness, breakdown behaviour and frothing. All gels and layers had a gelatin/water concentration of 5%. The total sugar concentration was 9% in the layered samples and 0, 9, 15 or 22.5% in the homogeneous samples. These concentrations corresponded to the concentrations in the single layers.A seven-layered sample with different sugar concentrations in the layers gave a higher early sweetness intensity than a homogeneous gel with the same mean total sugar concentration. All layered gels were similar in hardness, breakdown behaviour and frothing; for the homogenous samples, sensory hardness was decreased in samples with much sugar. These gels also fell into smaller pieces than the sugarless sample. This study shows that it is possible by controlling the sugar distribution within a sample to produce sweeter gels while the sugar content is maintained.