Micronization pretreatments for reducing the cooking time of lentils

For many grain and grain legume crops, a pretreatment step is often employed prior to processing to improve the quality of the final product. The pretreatment may be tempering, where a uniform specified moisture content in the grain is desired, or soaking, where moisture content is high and unevenly distributed. This study evaluated the effect of moisture contents and reagents as potential pretreatments for micronization (infrared heat treatment) of lentils, the objective being to reduce lentil cooking times. The texture of over-, under- and optimally cooked lentils was defined by sensory methods and by peak force values at 40% compression. As cooking time increased, sensory scores for hardness, chewiness and particle size decreased, as did peak force values. The peak force for optimally cooked lentils receiving no pretreatment was the control used to assess the effectiveness of a given pretreatment. The pretreatments studied were soaking of lentils, tempering of lentils to 20 or 40% moisture with water alone, and tempering to 20 or 40% moisture with solutions of various reagents: sodium salts of carbonate, bicarbonate, phosphate, tripolyphosphate and EDTA, and mixtures of citric and ascorbic acids. For tempering pretreatments, cooking time was reduced as moisture increased, but it was only at 40% moisture that added reagents were effective in reducing lentil cooking times. It was postulated that free water must be available in the cotyledon to allow reagents in the tempering water to reduce cooking time beyond that attainable with water alone. Potential reagents for tempering solutions used as successful micronization pretreatments were 2% sodium tripolyphosphate, mixtures of 1% citric and 2% ascorbic acid, and 150 ppm disodium EDTA. © 1998 SCI.     

不同破碎方法对大米品质的影响

采用干法和低温润米粉碎制备大米粉,研究不同破碎方法对大米品质的影响。通过理化检测结合快速粘度分析仪、质构仪和光学显微镜测定大米粉理化指标、糊化特性、质构以及微观结构的变化。结果表明与干法粉碎相比,珍桂、双桂、桂朝和越南香米四种大米经低温润米粉碎法粉碎后大米蛋白含量从原来的6.60%、6.09%、7.06%、6.86%显著增加为7.55%、6.67%、7.58%和9.05%(p<0.05);破损淀粉含量从原来的8.2%、7.9%、8.5%和7.2%显著减小为4%、3.8%、4.3%和3.3%(p<0.05);且低温润米粉碎大米粉具有糊化温度低、崩解值小、热糊稳定性好、凝胶硬度高等相对优异的糊化和质构特性值。此外,低温润米粉碎的大米粉颗粒形态在显微镜下表面相对平整,破坏程度低。     

油炸工艺对高油酸花生品质与微观结构的影响

研究植物油种类、油炸温度、油炸时间对油炸花生感官品质、质构特性的影响,并通过激光共聚焦扫描显微镜（CLSM）和扫描电镜（SEM）观察油炸前、后花生微观结构的变化。结果表明,油炸最佳工艺条件：植物油种类为棕榈油,油炸温度140℃、油炸时间8 min。在该工艺条件下油炸花生色泽均匀,口味香甜,口感酥脆,硬度7.30 kg,脆性0.27 mm,感官得分48.9,水分含量0.87 g/100 g、酸价1.20 g/100 g、过氧化值0.09 g/100 g,扫描电镜与激光共聚焦显微镜观察的结果一致,花生在油炸后细胞壁断裂,细胞质丢失,出现孔状结构,细胞内油体增加,蛋白体聚集。     

两种优质鸡和快大鸡肉品质特性及微观结构的比较研究

比较研究两种优质鸡(清远麻鸡、三黄鸡)和快大鸡的鸡肉品质指标、质构特性和微观结构,结果表明,快大鸡的屠宰率、全净膛率、胸、腿、翅重占全净膛率等都高于清远麻鸡和三黄鸡;清远麻鸡和三黄鸡的蒸煮损失率和贮藏损失率都低于快大鸡;清远麻鸡的弹性、黏结性、咀嚼性和回复性比快大鸡高,硬度比快大鸡低。肌纤维的电镜观察结果显示,同一鸡种的胸肌纤维直径小于腿肌。以胸肉比较,不同品种(系)的肌纤维直径趋势是快大鸡(28.74μm)>三黄鸡(23.78μm)>清远麻鸡(23.31μm);而肌纤维密度则相反,清远麻鸡(1594.75根/mm2)比三黄鸡(1460.08根/mm2)和快大鸡(906.18根/mm2)高。肌纤维直径与密度可以反映肌肉的品质,肌纤维越细,肉品嫩度越好。     

微细化处理对食用菌五谷面条蒸煮及质构特性的影响

研究微细化处理食用菌五谷面粉对其面条蒸煮及质构的影响,采用微粉碎技术对食用菌五谷混合粉进行处理,并对食用菌五谷面条蒸煮特性、质构特性、表面微观结构等进行检测。结果表明最佳物料粒度为160目(0.097 mm),其体积等效粒径为70.5μm。微细化处理后的混合粉粒径主要分布在3~40μm和40~500μm两个区间内,微细化处理后食用菌五谷面条的最佳蒸煮时间为(13.45±0.26)min;复水率、干物质吸水率分别增加到(93.20±2.28)%、(128.63±2.57)%,干物质损失率、熟断条率分别降低为(6.72±0.09)%、(5.00±0.32)%。质地剖面分析(texture profile analysis,TPA)实验结果表明面条延展性为(-4.09±0.10)g/s,硬度、黏性分别降低至(310.39±7.39)g、(-4.87±0.65)g·s,咀嚼性增加到(102.14±3.31)g·s;拉伸实验结果表明160目(0.097 mm)食用菌五谷面条拉断力最大,为(19.43±0.18)N,拉伸距离为(53.90±0.87)mm。扫描电子显微镜观察结果表明,随着微细化程度增加,面条表观改善,结构变得更加致密光滑,孔隙相对减少,有利于提高食用菌五谷面条的蒸煮耐性,改善其质构持性。     

猪肉火腿肠综合品质的研究

对在超市购买的3种猪肉火腿肠的理化指标、微生物指标、感官评定、质构特性、微观结构和色泽进行了研究,结果表明,3种猪肉肠的硬度、胶着性、咀嚼性、剪切力和亮度值存在显著性差异;猪肉肠A和C的弹性与猪肉肠B的弹性存在显著性差异;猪肉肠A和B的内聚性与猪肉肠C的内聚性存在显著性差异;3种猪肉肠的硬度和胶着性、咀嚼性和剪切力数值依次减小;猪肉肠A、B的理化指标和微生物指标总体相对较好,猪肉肠A的色泽最好,猪肉肠B的口感、风味和微观结构最好,两者的总体接受性相当,猪肉肠C的嫩度好。综合各指标总体评价,猪肉肠A和B的综合品质好于猪肉肠C。     

Sous Vide加工方法对牦牛肉品质的影响

以牦牛肉背最长肌为原料,采用Sous Vide加工方法,研究不同热处理温度、热处理时间和肉块厚度对牦牛肉感官品质、蒸煮损失率、质构及微观结构的影响。在单因素试验基础上,进行正交优化试验,确定Sous Vide加工牦牛肉的最佳工艺条件。结果表明：Sous Vide加工方法对牦牛肉感官品质、剪切力、蒸煮损失率影响较大,通过正交试验得到Sous Vide加工牦牛肉的最佳工艺条件为热处理温度70 ℃、热处理时间135 min、肉块厚度3.0 cm;经Sous Vide处理的牦牛肉肌纤维束结构变得松散,肌纤维密度降低,肌束膜部分结构被破坏,牦牛肉嫩度和感官品质均优于对照组。     

挤压改性糙米—小麦混合粉糊化特性与面条品质关系研究

将不同挤压条件下得到的糙米粉与小麦粉按1∶1比例进行混合,研究挤压改性对混合粉糊化特性及面条品质的影响,并分析两者之间的相关性。结果表明:物料水分的增加使混合粉峰值粘度增加,最低黏度和衰减值减小,挤压温度的增加,使混合粉峰值粘度、最低黏度和衰减值逐渐减小,回生值增大,相比之下,螺杆转速对混合粉以及面条特性影响较小;SEM试验结果显示添加挤压糙米粉的面条,其内部形成连续性网状结构;相关性分析结果表明,面条吸水率与混合粉的最终黏度和回生值呈显著正相关,面条坚实度与混合粉峰值粘度、衰减值和最终粘度呈显著负相关。     

鸡肉火腿肠综合品质的研究

对在超市购买的3 种鸡肉火腿肠的理化指标、感官评定、质构特性、微观结构和色泽进行研究,结果发现：3 种鸡肉肠的硬度、胶着性、咀嚼性、亮度和白度存在显著性差异,弹性和内聚性无显著性差异,3 种鸡肉肠的硬度、胶着性和咀嚼性均依次较小;鸡肉肠A、B 的理化指标测定结果相对较好,鸡肉肠A 的香味最好,鸡肉肠B 的口感、微观结构和色泽最好,鸡肉肠C 的嫩度好。综合各指标总体评价,鸡肉肠B 的综合品质最好。     

Comparisons of good- and poor-cooking lentils

Good- and poor-cooking Canadian cultivars of lentils, CDC Richlea, Rose and Laird, were compared for shear force, seed phosphorus (P), phytic acid (PA), water uptake and for seed coat composition and structure. Good-cooking CDC Richlea and Rose lentils (shear force 4.9 kg g^?1) contained 24–33% more P and 48% more PA than poor-cooking lentils (shear force 7.0–8.1 kg g^?1). The poor-cooking CDC Richlea lentil (shear force 8.1 kg g^?1) had smaller hydration coefficients, solids lost, and water absorption than the good-cooking ientil (shear force 4.9 kg g^?1), but differences disappeared in dehulled good- and poor-cooking lentils of the same cultivar. Regression analysis showed that the good- and poor-cooking lentils absorbed water at the same rate. Therefore, smaller water-uptake was not responsible for the poor-cooking condition. Seed coat compositions of good- and poor-cooking Laird lentils were generally similar; the major components of the seed coats were cellulose and hemicellulose, forming about 56% of the non-starch polysaccharide and lignin fractions. Light microscopy of isolated seed coats showed a more tightly packed epidermis layer and a larger, thicker cell-walled hypodermis layer in the poor-cooking lentil than in the good-cooking lentil.     

The relative effect of milk base, starter, and process on yogurt texture: a review

Yogurt is a milk curd produced all over the world, obtained by a lactic fermentation of a milk base enriched with milk proteins, and sometimes sugars and thickeners. One of the most important sensorial attributes for yogurt is texture, which could be assessed by sensory or instrumental analysis. A lot of work has been published in studying the contribution of milk base, starter, and process on yogurt texture in order to develop new textures, or simply to reduce fat content, or the level of addition of protein and thickener in milk. However, these studies are limited to only a few factors. The topic of this review was to synthesize the data of literature, with the aim of extracting and classifying factors on the basis of their influence on yogurt texture. Three factors, milk base heating, starter, and yogurt shearing after fermentation, respectively, play a key role in the elaboration of texture. The control of these three parameters allows the improvement of the textural attributes of yogurts by 2 to 15 times.     

ADSA Foundation Scholar Award: Possibilities and challenges of exopolysaccharide-producing lactic cultures in dairy foods

Exopolysaccharides (EPS) from lactic acid bacteria are a diverse group of polysaccharides exhibiting various functional properties. Two forms of EPS are produced by lactic acid bacteria: capsular and unattached. Capsular EPS does not cause ropiness nor does production of unattached EPS ensure ropiness. The functions of EPS in dairy products are not completely understood. This is for 2 main reasons: the major variations among exopolysaccharides even from the same group of micro-organisms, which makes it difficult to apply information from one EPS to others, and the lack of availability of techniques with the ability to observe the microstructure and distribution of the highly hydrated EPS in fermented dairy products. The introduction of relatively new microscopic techniques such as confocal scanning laser microscopy and cryo-scanning electron microscopy made it possible to directly observe the distribution of fully hydrated EPS in dairy products. Recently, EPS produced by nonropy strains have drawn the attention of the dairy industry. This is because of the ability of some nonropy strains to produce large capsular and unattached EPS that would improve the texture of dairy products without causing the undesirable slippery mouthfeel produced by the ropy strains. Factors affecting functions of EPS are their molecular characteristics and ability to interact with milk proteins. Studying the interaction between EPS and milk proteins is complex because EPS are gradually produced during fermentation, unlike polysaccharides added directly to milk to stabilize the fermented product. The concentration and possibly molecular characteristics of EPS and protein characteristics such as charge and hydrophobicity change during fermentation. Consequently, the interaction of EPS with proteins might also change during fermentation. Exopolysaccharides provide functions that benefit reduced-fat cheeses. They bind water and increase the moisture in the nonfat portion, interfere with protein-protein interactions and reduce the rigidity of the protein network, and increase viscosity of the serum phase. This review discusses the production of capsular EPS and their role in structure formation in fermented milk, the mechanism of ropiness formation, and applications of EPS-producing cultures in reduced-fat cheeses.     

毛霉发酵对豆制品的质构和微观结构的影响

利用质构仪和扫描电子显微镜研究毛霉发酵豆腐的质构和微观结构,通过电泳分析豆腐的蛋白质水解情况,并与未发酵豆腐进行对比。结果表明,与未发酵豆腐相比,发酵豆腐的硬度和黏性增大,内聚性和弹性减小。其微观结构较均匀致密。电泳分析和微结构分析均显示出大分子量的蛋白质在豆腐发酵过程中的降解。     

卵形鲳鲹肌肉原料特性及食用品质的分析与评价

为探究卵形鲳鲹肌肉的原料特性及食用品质,对卵形鲳鲹的形体参数、各部分质量分数及采肉率、肌原纤维直径、质构、色泽、蒸煮损失率、滴水损失率、失水率、pH值、基本成分质量分数、蛋白质组成、矿物质元素含量、脂肪酸组成、氨基酸含量及挥发性风味物质比例等多方面指标进行测定和分析。结果表明：卵形鲳鲹肥满度高但采肉率低,加工下脚料多;其肌原纤维直径为（77.84±4.94）μm,肉质细嫩;腹部肌肉的白度最高,硬度和咀嚼性明显高于背部和尾部,更适合加工为即食鱼片;卵形鲳鲹肌肉的水分和粗脂肪质量分数分别为（71.65±0.55）%、（8.74±0.55）%;肌肉中钠、镁含量相对其他鱼类略高,饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸比例接近1∶1∶1,必需氨基酸指数为93.51,己醛、壬醛、2-乙基己醇为其主要挥发性风味物质。本研究可为卵形鲳鲹的多元化加工利用提供基础数据和参考。     

添加剂对豆腐皮质构特性及微观结构的影响

本文研究了甘油、海藻糖、蔗糖酯、单甘酯及其复配添加剂对豆腐皮质构特性、微观结构及其他特性的影响。结果表明:甘油、海藻糖、蔗糖酯、单甘酯能够改善豆腐皮的质构特性。甘油、海藻糖、单甘酯复配组合(甘油2%、海藻糖0.5%、单甘酯0.5%)对于豆腐皮的综合品质提升效果最好。通过透射电镜和红外光谱观察豆腐皮的微观结构,发现添加剂小分子的介入能使豆腐皮网络结构均匀致密,从而改善其机械性能。      

Texture of Cheddar Cheese as Influenced by Fat Reduction

Cheddar cheeses with five different fat levels (34, 32, 27, 21, and 13 %) were manufactured in a randomized block design experiment and replicated four times. Cheeses were ripened for 4 months at 7°C. Microstructure was studied using Scanning Electron Microscopy (SEM). Texture characteristics (adhesiveness, cohesiveness, hardness, and springiness) were determined by Texture Profile Analysis (TPA) using the Instron Universal Testing Machine and a trained sensory panel. Scanning electron micrographs showed that the open-intricate microstructure of the cheeses was lost with a decrease in fat content. Hardness and springiness increased while adhesiveness and cohesiveness of the cheeses decreased with decreasing fat content. Texture attributes were influenced by the nature of the protein matrix that resulted due to fat removal.     

冻结模式对冷冻熟制鹰嘴豆杂粮面条品质的影响

为探究冻结模式对冷冻熟制鹰嘴豆杂粮面条品质的影响,利用质构仪、扫描电镜、色差仪等仪器测定不同冻结模式下冷冻熟制鹰嘴豆杂粮面条蒸煮品质、质构特性、微观结构、色泽、感官品质的差异。结果表明：冷冻熟制鹰嘴豆杂粮面条的蒸煮损失率在-18 ℃最大,-50、-80、-196 ℃条件下无显著差异;面条吸水率随冻结温度的降低呈下降趋势,回复力、咀嚼性、坚实度呈上升趋势;-80 ℃和-196 ℃条件下面条的硬度、弹性、黏性、最大拉伸强度、拉伸断裂距离、坚实度无显著差异。扫描电镜结果显示,冷冻熟制鹰嘴豆杂粮面条的面筋蛋白网络结构随冻结温度的降低逐渐变得紧密,孔洞逐渐减小。-196 ℃时面条的面筋蛋白网络结构最紧密,表面粗糙度最低。色泽变化表明面条的L*值随冻结温度的降低依次增大,a*、b*、ΔE*值依次减小。感官评价结果显示随冻结温度的降低,面条感官评分依次增加。综上所述,冻结温度达到-80 ℃时,有利于保证冷冻熟制鹰嘴豆杂粮面条的品质。