蔗渣膳食纤维挤压改性的研究(Ⅱ)──挤压降解机理及挤压对纤维物化性质的影响

借助于气相色谱和X-衍射的分析表明，挤压蒸煮处理后蔗渣膳食纤维内部组成成分得以调整与重组。部分不溶性阿拉伯木聚糖会溶解或断裂某些连接键转变成可溶性阿拉伯木聚糖，但纤维的聚合物结构并没发生深度降解或破坏。挤压蒸煮还对膳食纤维的物化性质产生不同程度的影响。     

Extrusion-cooking of starch protective loose-fill foams

One of the most interesting alternatives to EPS is extrusion of starch-based materials. TPS-based biocomposites can be processed, in a one-step process, via an extrusion-cooking. Wide program of the experimental works with application of extrusion-cooking for production of starchy loose-fill foams has been started in the Department of Food Process Eng., Lublin University of Life Sciences in 2012. The object of the study is to achieve commercially acceptable biodegradable products based on locally produced potato, corn and wheat starch, which can replace popular EPS. Results of the first phase of the study are presented in the paper. The measurements of glass transition temperature of TPS samples showed that with glycerol content growth in the blend, the Tg of the obtained material decreases almost linearly. In the case of potato TPS, the highest observed Tg was 187.7 ?C for 7.0% glycerol and the lowest was at 18.1 ?C for 30% glycerol. Properties of the loose-fill foams highly depend on raw materials and process parameters used in production. In addition of plasticiser or other additives, different temperature of processing is causing changes in product's properties. All starch-based foams had high open-cell content and the expansion was attributable to the escape of water as steam during processing, resulting more than 80% open cells. The foam density of starch-based products ranged between 18.7 and 30.5 kg/m³. The products were at least 2.5 times more dense than EPS-based foams. The best products achieved by us up till now are the corn TPS-based foams containing 3% plasticizer and 1% poly-vinyl alcohol. The energy consumption during extrusion-cooking depended on the material composition of the blends, temperature and the screw rotation speed used during processing. Average value of SME was about 2.52 × 10⁵ J/kg, which is equivalent to 0.07 kW h/kg.     

Effect of extrusion conditions on physicochemical and sensorial properties of corn-broad beans (Vicia faba) spaghetti type pasta

Corn-broad bean spaghetti type pasta was made with a corn/broad bean flour blend in a 70:30 ratio, through an extrusion-cooking process (Brabender 10 DN single-screw extruder with a 3:1 compression ratio). The effect of temperature (T = 80, 90 and 100 °C) and moisture (M = 28%, 31% and 34%) on the extrusion responses (specific consumption of mechanical energy and pressure) and the quality of this pasta-like product (expansion, cooking-related losses, water absorption, firmness and stickiness) was assessed. The structural changes of starch were studied by means of DSC and XRD. The extrusion-cooking process, at M = 28% and T = 100 °C, is appropriate to obtain corn-broad bean spaghetti-type pasta with high protein and dietary fibre content and adequate quality. The cooking characteristics and resistance to overcooking depended on the degree of gelatinisation and formation of amylose–lipid complexes. The critical gelatinisation point was 46.55%; beyond that point, the quality of the product declines.     

双螺杆食品挤压蒸煮研究的进展

本文综述了双螺杆食品挤压蒸煮研究的进展,包括大豆蛋白的挤压组织化机理、流变性能、挤出理论、挤出机头和食品挤出试验的系统分析模型,主要是针对大豆蛋白质物料。     

Antioxidant activity and dietary fibre in durum wheat bran by-products

Milling of wheat generates by-products, which can be used to improve the technological performance and/or to integrate foods with healthy compounds. The aim of this paper was to select fractions of durum wheat bran having different functional and nutritional characteristics. Wheat bran by-products were obtained by an industrial milling process. Beside the single fractions, two commercial products Bran & Brain 50 and 70, obtained by blending some of the durum wheat fractions were also studied. All samples were investigated for water holding capacity, soluble and insoluble dietary fibre content and for their antioxidant activity. The soluble fibre content of the durum wheat by-product ranged between 0.9% and 4.1%; while that of insoluble fibre between 21% and 64%. B&B 70 has a TDF content of 61%, while B&B 50 has 42%. The water holding capacity of each fraction is strictly related to the amount of insoluble fibre and to the granulometry of the by-products. Cooking-extrusion process does not affect the amount of soluble fibre; by contrast, a significant increase of the insoluble fibre was detected. The antioxidant activity is higher for the internal bran fraction and it increases in fractions having reduced granulometry. The antioxidant activity of some durum wheat by-product fractions is comparable to that of widespread fruits and fresh vegetables, likely due to the presence of fibre-bound phenol compounds. The high fibre content and antioxidant activity of durum wheat bran by-products can be of particular interest for their use in cereal-based products.