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.     

Comparative assessment of textural properties and microstructure of composite gels prepared from gelatine or gellan with maize starch and/or egg white

Single component gels (SCG) were formed from gelatine, gellan, maize starch or egg white, while binary composite gel (BCG) and ternary composite gel (TCG) were formed by mixing gelatine or gellan with maize starch and/or egg white. Each type of SCG exhibited distinct textural and microstructure characteristics. Gelatine‐SCG was the softest to hold but has the strongest and the most elastic network compared with other SCG. The effects of gelatine or gellan proportions on the textural properties of composite gels were investigated using mixture design experiments. Gelatine and gellan yielded composite gels that showed different textural behaviours and microstructure. All BCG and TCG blends showed antagonistic effects; the composite gels were softer and weaker as compared to the SCG. Gelatine‐BCG and TCG were comparatively stronger than those of gellan due to their different gelling mechanisms, in which the former had yielded a denser network structures as compared to the latter.     

Utilization of two plant polysaccharides to improve fresh goat milk cheese: Texture,rheological properties,and microstructure characterization

This study aimed to evaluate the effects of added jujube polysaccharide (JP) and Lycium barbarum polysaccharide (LBP) on the texture, rheological properties, and microstructure of goat milk cheese. Seven groups of fresh goat milk cheese were produced with 4 levels (0, 0.2, 0.6, and 1%, wt/wt) of JP and LBP. The goat milk cheese containing 1% JP showed the highest water-holding capacity, hardness, and the strongest rheological properties by creating a denser and more stable casein network structure. In addition, the yield of goat milk cheese was substantially improved as a result of JP incorporation. Cheeses containing LBP expressed lower fat content, higher moisture, and softer texture compared with the control cheese. Fourier-transform infrared spectroscopy and low-field nuclear magnetic resonance analysis demonstrated that the addition of JP improved the stability of the secondary protein structure in cheese and significantly enhanced the binding capacity of the casein matrix to water molecules due to strengthened intermolecular interactions. The current research demonstrated the potential feasibility of modifying the texture of goat milk cheese by JP or LBP, available for developing tunable goat milk cheese to satisfy consumer preferences and production needs.     

淀粉凝胶储藏过程中消化特性和质构特性的变化

采用酶解法和全质构分析分别测定了红薯、绿豆和马铃薯淀粉凝胶在储藏过程中的消化特性和质构特性,并对消化特性与质构特性指标之间进行简单相关和逐步回归分析。结果表明:在25℃储藏10 d内,绿豆淀粉凝胶的老化性能强于红薯淀粉和马铃薯淀粉。淀粉凝胶的消化率降低,慢消化淀粉和抗性淀粉含量增加,快消化淀粉含量降低;淀粉凝胶的硬度随储藏时间的延长逐渐增加,回复值则逐渐减小。快消化淀粉含量、硬度和回复值可作为淀粉凝胶类食品的老化评价指标。     

物理作用力对大豆分离蛋白凝胶质构特性的影响

本文研究了不同阴离子的中性盐、尿素和丙二醇对大豆分离蛋白凝胶质构特性的影响。结果表明,在中性盐浓度较低时(≤0.1mol/L),中性盐的静电中和作用显著影响凝胶的质构特性,而当盐浓度较高时,中性盐的阴离子对蛋白质分子构象稳定性和疏水相互作用的影响成为影响凝胶质构特性的主要因素;尿素和丙二醇对凝胶质构特性的影响表明,氢键也是影响大豆分离蛋白质构特性的主要作用力。     

Amylose and Protein Contents of Rice Cultivars as Related to Texture of Rice-based Fries

Mixtures of short-, medium-, and long-grain rice flours, defatted rice bran, salt, and water were extruded and fried to produce French fry-like products. Amylose and protein correlated positively with instrumental measures of hardness and gumminess. Water contents of frozen and fried fries correlated negatively with hardness and gumminess. Low protein rice cultivars retained more water than high protein cultivars during extrusion followed by cooling. Amylose content correlated negatively with water content of fried fries. Fries formulated from waxy rice had hardness and gumminess comparable to commercial French-fried potatoes, but all other fries were too hard and gummy.     

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。     

基于质地多面分析法对不同苹果品种果肉质构特性的分析

为了细致研究"华红"苹果贮藏期间果肉质地变化和不同苹果品种质构特性差异,本实验以套袋和未套袋"华红"苹果为试材,应用质地多面分析法定期测定贮藏期间果肉质地参数;以及以不同熟期"华红"、"华苹"、"寒富"、"红星"、"嘎拉"、"津轻"为试材,比较不同苹果品种果肉质地品质差异,同时分析各质地参数之间相关性。"华红"套袋和未套袋果肉质地参数在常温贮藏过程中变化趋势基本一致,且未套袋果肉的各项质地参数稍高于套袋的。硬度呈下降趋势,在黏附性、内聚性、弹性、咀嚼性、回复性方面,贮藏0 d的果实与48 d相比稍有升高。"华红"果肉贮藏期间质地参数变化相关性和6个苹果品种之间质地参数相关性有相似处,内聚性与弹性、回复性、咀嚼性都呈正相关,弹性与回复性、咀嚼性都呈较好地正相关,回复性与咀嚼性呈较好的正相关。不同的是,"华红"果肉硬度与黏附性、内聚性呈负相关,而不同品种之间果肉硬度与内聚性、弹性、回复性、咀嚼性呈高度正相关。不同品种之间各质地参数也进行了量化比较。综上说明本实验选用的P5探头测定的果肉内聚性、弹性、回复性、咀嚼性能反映"华红"果肉质地变化规律,适用于苹果果肉质地品质的客观评价。硬度、内聚性、弹性、回复性、咀嚼性质地参数中的一项或多项可以作为评价"华红"果肉质地和比较这6个苹果品种果肉质地差异性的重要参数。     

Structure and Texture Properties of Fried Potato Products

Potatoes are the fourth most important vegetable crop in the world, and in 2003, it was a 2.7 billion dollar business in the US alone. Nearly one-third of the potato production is processed into par-fried frozen potatoes and fried chips (snacks). Frying imparts desirable taste and textural properties to these products, the latter described usually by the sensorial term crispness. Frying is reviewed as a structuring process, and methodologies to determine texture in fried potato products are discussed. It is demonstrated that the histological and microstructural heterogeneity of potato tubers have hampered clear interpretation of experimental data and a rigorous modeling of frying. Moisture uptake during post-frying is critical in the loss of crispness (limpness) of fries and in softening of potato chips. Methods to evaluate these changes and alternatives to prolong the shelf life are discussed.     

Structure and Texture Properties of Fried Potato Products

Potatoes are the fourth most important vegetable crop in the world, and in 2003, it was a 2.7 billion dollar business in the US alone. Nearly one-third of the potato production is processed into par-fried frozen potatoes and fried chips (snacks). Frying imparts desirable taste and textural properties to these products, the latter described usually by the sensorial term crispness. Frying is reviewed as a structuring process, and methodologies to determine texture in fried potato products are discussed. It is demonstrated that the histological and microstructural heterogeneity of potato tubers have hampered clear interpretation of experimental data and a rigorous modeling of frying. Moisture uptake during post-frying is critical in the loss of crispness (limpness) of fries and in softening of potato chips. Methods to evaluate these changes and alternatives to prolong the shelf life are discussed.     

热稳定冰结构蛋白对小麦淀粉凝胶 冻融稳定性的影响

研究燕麦粉和女贞叶中热稳定冰结构蛋白(TSISP)对淀粉凝胶冻融稳定性的影响。应用差示扫描量热仪(DSC)、扫描电子显微镜(SEM)和质构仪分别研究燕麦粉、女贞叶TSISP对淀粉凝胶冻融后析水率、可冻结水含量、超微结构、硬度及弹性的影响。结果表明：冻融过程显著地增加淀粉凝胶析水率、可冻结水含量,严重地破坏淀粉凝胶超微结构、增加孔洞尺寸、减小孔洞均匀性,最后导致淀粉凝胶硬度明显增大,弹性明显减小;而燕麦粉和女贞叶中TSISP的添加显著地减小淀粉凝胶冻融后析水率和可冻结水含量,同时显著地改善淀粉凝胶超微结构,使得淀粉凝胶孔洞增大幅度明显得到抑制,孔洞均匀性更好,结果也对淀粉凝胶质构产生明显的改善效果,延缓硬度的增加和弹性的减小,使得冻融后淀粉凝胶的总体品质得以提高。     

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。      

EFFECT OF ADDED SALT ON TEXTURAL PROPERTIES OF HEAT-INDUCED GELS MADE FROM GUM–PROTEIN MIXTURES

Large deformation rheological tests were employed to determine the textural differences in heat‐induced gel systems. Three different large deformation rheological methods (viscosity index and apparent elasticity, texture profile analysis (TPA) and torsional fracture) were employed to study the dependence of the ion type on the textural properties of heat‐induced mixed protein–gum gels. Protein–gum mixed solutions were prepared with bovine serum albumin (BSA) or egg white albumin (EWA) (20% w/v) with κ‐carrageenan (KCG), gellan (GLN) or xanthan gums (XNT) (0.5% w/v) at 0.1 M sodium chloride (NaCl), potassium chloride (KCl) or no added salt. Despite inherent differences in protein type, the main effect on the textural properties evaluated was for the kind of salt added, since potassium ions, with a strong influence on KCG and GLN gelation, affected the parameters related to the structure or hardness of the samples. There was no significant effect on parameters associated with sample ductility or elasticity. GLN formed stronger gels than KCG, whereas XNT did not perform as well in gel formation since it does not contribute to protein matrix formation. The results indicated that potassium may be substituted for sodium ions at low ionic strengths in foods where the incorporation of KCG or GLN helps to improve texture and related features.     

转谷氨酰胺酶诱导调质大豆分离蛋白凝胶的水分分布及凝胶特性

利用低场核磁共振技术、质构仪、差示扫描量热仪等对调质大豆分离蛋白凝胶水分分布、凝胶特性及微观 结构进行测定,研究调质大豆分离蛋白的蛋白组成对转谷氨酰胺酶诱导的蛋白凝胶的影响。结果表明：调质大豆分 离蛋白中11S球蛋白所占比例对蛋白凝胶水分分布、凝胶特性及微观结构有显著相关性。11S球蛋白的质量分数由 60%提高到80%时,蛋白凝胶的横向弛豫时间T2先缩短后延长;凝胶的硬度、黏性、咀嚼性3 项指标值均有不同程 度的降低;蛋白凝胶的热稳定性先提高后降低,70%的11S球蛋白蛋白凝胶ΔH最低,凝胶中水分不易失去;11S球 蛋白质量分数分别为60%与70%的大豆分离蛋白凝胶形成的微观结构表面较平整,孔洞较小且相对均匀。     

大米脂肪模拟物对低脂酸奶质构特性及微观结构的影响

本研究用α-淀粉酶将大米粉水解制备了大米脂肪模拟物,将此模拟物应用于酸奶中制备了几种添加不同量的大米脂肪模拟物的低脂酸奶,并与不添加脂肪模拟物的全脂对照和低脂对照酸奶比较,进行了成分分析、质构分析、微观结构分析及感官评价.结果表明添加大米脂肪模拟物的低脂酸乳显示出了与全脂对照酸乳相似的感官特性、质构特性和消费者可接受性(p＞0.05),并表现出了较全脂对照酸奶较低的脂肪含量和较空旷、松散的蛋白网状微观结构.     

干燥条件对橘皮颜色与结构性能的影响

柑橘皮富含经济和药用价值,为寻求更优的干燥方式以实现资源全利用,本文对比研究了真空冷冻、热风、中短波红外干燥橘皮的颜色和结构性能。结果表明:不同干燥条件对橘皮色泽和结构性能影响显著(p0.05)。褐变引起橘皮总色差值变化,而类胡萝卜素降解导致b值降低;在干燥温度60℃~90℃范围内,干燥橘皮L值,a值,b值和类胡萝卜素含量随干燥温度升高而降低,ΔE值和褐变度随干燥温度升高而升高。微观结构的改变则为干燥橘皮粗纤维含量、质构参数和干燥效率、复水性等性质研究提供了参考方法,微观结构疏松且未受损伤,孔隙大,分布均匀,则粗纤维含量较高,硬脆度适中,复水性好,反之结构性能较差;较真空冷冻和热风干燥,中短波红外低温干燥(60℃~70℃)对橘皮的颜色和结构保持最好。本文为橘皮的干燥产业化生产提供了重要理论依据。