枣泥馅料质构参数与感官品质的相关性

针对目前枣泥馅料品质缺乏客观性评价标准的问题,通过分析测试条件对枣泥馅料TPA参数的影响,确定枣泥馅料质构仪质地分析法(Texture Profile Analysis,TPA)在探头的测试速度5 mm/s,对枣泥表面的压缩程度为50%,测试停留时间为5 s,探头对枣泥馅料的触发力为5g时,此时得到的TPA参数对枣泥馅料的测验条件最佳;通过采用感官评定中的质地多面剖析方法,制定了枣泥馅料评分细则。结合对感官评分之间的相关性进行皮尔逊分析结果得知感官评定指标的粗糙度与易碎性、硬度、紧密性之间具有不同程度的影响(皮尔逊系数r在0.9～1之间,p0.01);对TPA参数与感官评分的相关性分析得出,质构仪(TPA)分析参数中硬度、黏附性、凝聚性、咀嚼性和回复性与感官评分都在0.01水平上显著相关。由此提出以硬度、黏附性、凝聚性、咀嚼性和回复性5个TPA参数作为客观评价馅料品质的指标。     

COMPARISON OF TWO INSTRUMENTAL METHODS WITH SENSORY TEXTURE OF PROTEIN GELS2

The textural attributes of 8 different heat-induced protein gel preparations evaluated by torsion failure testing and Instron texture profile analysis (TPA) were compared to sensory ratings by a trained texture profile panel. The gels presented a wide range of textural properties as determined by the instrumental and sensory parameters. Among the instrumental parameters, true shear strain at failure was the most frequent and significant predictor of sensory notes. Initial shear modulus and 50% compression force had the poorest correlations with sensory notes. Comparison of the two instrumental tests produced high correlations between shear stress at failure and TPA hardness; true shear strain at failure and TPA cohesiveness; and, initial shear modulus and 50% compression force. High correlations were also observed among various panel notes. Canonical correlation analyses showed that sets of linear combinations of parameters from each one of the 3 tests (torsion, TPA or sensory) were highly correlated to sets from either of the other two. Regression equations relating each of the instrumental tests to sensory notes were developed. Of the torsion failure parameters, the logarithm of true shear strain most commonly appeared in the equations. Of the TPA parameters, cohesiveness and its logarithm were the terms that were most frequent. High R² values were obtained for regression equations developed for predicting torsion failure parameters based on TPA parameters.     

The thermal kinetics of texture change and the analysis of texture variability for raw and roasted hazelnuts

Texture changes of hazelnuts which were dry roasted at temperatures from 120 to 180 °C, for durations ranging from 5 up to 60 min, were studied using instrumental analysis. The textural changes in hazelnuts were represented by the fracture force obtained from compression tests. The magnitudes of the parameters for the corresponding texture change model were determined using one step non‐linear regression. The order of the reaction was found by plotting isothermal curves of texture response against time; statistical analysis of the data showed that it was best represented by a first‐order reaction. The rate constants were assumed to have an Arrhenius‐type dependence on temperature. The activation energy and the frequency (pre‐exponential) factor at a reference temperature (150 °C) were determined to be 39.25 kJ mol^?1 and 0.0421 s^?1, respectively. Young's modulus and the fracture stress for roasted hazelnuts were calculated to be 4.93 and 1.54 MPa, respectively. Both roasting temperature and time had significant effects on the textural changes in hazelnuts, and the variability in the texture decreased during the roasting process. The physical properties of hazelnuts were correlated with the texture response. A possible major factor causing the high variability in texture was the internal cavity present at the core of each hazelnut. The development of a model of the thermal kinetics of texture change over a large roasting temperature and time range should allow optimization studies to be used for determining the best roasting schedule in terms of delivering the required product texture.     

Low Frequency Ultrasonics for Texture Measurements in Cooked Carrots (Daucus carota L.)

The use of low frequency ultrasound for texture evaluation of carrots cooked at 100°C for 0 to 15 min was examined. Uniaxial compression, microscopy and analyses of density and dry matter were used to provide comparative results for evaluating relationships between texture and ultrasonic parameters. During the first minutes of cooking the sound velocity (v) decreased and a positive correlation was found between compressive Young's modulus (E_cy) and sound velocity (v). During extended heating, sound velocity (v) increased and attenuation (α) decreased as a result of changes in mechanical properties and air and water content of the tissue.     

五种苹果质构测定方法的比较及与感官评价的相关性分析

为比较5种苹果质构不同测定方法,采用剪切法、穿刺法和TPA压缩法测定了辽宁地区5种主栽苹果的质构特征,同时研究了不同测试条件对测定指标的影响,并分析了仪器测定与感官评价结果的相关性。结果表明剪切、穿刺和TPA压缩均能测得苹果的硬度特征,并区分不同品种间的差异,去皮果肉硬度大小依次为王林 > 红富士 > 国光 > 乔纳金 > 黄元帅;穿刺法检测显示果皮对苹果质构有显著影响(P<0.05),且不同穿刺部位的质构差异显著(P<0.05),其中果顶部位穿刺硬度值最大,其次为果肩和赤道;与感官评价相关性分析显示最大穿刺模量与感官脆性极显著相关(r=0.638,P<0.01),可作为苹果脆性的表征指标;对TPA法,随着压缩形变量增加,苹果硬度测定值显著增加(P<0.05),而内聚性显著减小(P<0.05),且形变量为25%时与感官评价相关性最好。本研究表明穿刺法和TPA法均适用于苹果质构的测定,果皮及穿刺位点对穿刺影响显著,最大穿刺模量可用于表征苹果脆性指标;压缩形变量为25%时TPA法所测得质构参数与感官评价结果相关性最好。     

豆沙质地特性的感官评定与仪器分析

用质构仪对豆沙进行穿孔、剪切、全质构分析(TPA)以研究其质地特性。分析各质构参数之间的相关性,探索豆沙感官评价和仪器测定参数之间的关系,得出了感官评定指标以仪器测定参数为变量的多元线性回归模型。结果表明：除TPA测试的弹性、凝聚性外,质构仪测试的其他指标如硬度、黏着性、剪切力等均与感官指标有很好的相关性。除感官凝聚性外,穿孔、剪切、全质构分析3种质地测试方法结合使用可以对其余各感官指标进行预测,且各预测模型都有很高的显著性。     

The role of lipid oxidation on biscuit texture during storage

The role of lipid oxidation and humidity absorption on the shelf life of biscuits was analysed. Biscuits with low lipid and sugar content were prepared employing different oils, and texture changes that biscuits experience during storage were studied. Water activity, peroxide value, malonaldehyde content and colour were also determined at different storage times. The maximum peroxide level was between 1 and 1.5 mmol kg^?1 of oil, at 166 days of storage. Values of malonaldehyde were between 5.2 and 15.8 nmol g^?1 of dry sample. Water activity and peroxide value influence the biscuit texture (P ≤ 0.05). To study the effects of both factors simultaneously, a mathematical model was adjusted to the data. Results indicate that an increase in the peroxide level, even at low level of lipid oxidation, increases Young's modulus and leads to a harder biscuit, while the humidity absorption lowers the fracture stress and Young's modulus.     

Understanding the crispy–crunchy texture of raw red pepper and its change with storage time

Red sweet peppers held in cold storage were periodically sampled at 1-week intervals over a 3-weeks period using three-point bending, puncture, cutting, and Volodkevich (coupled with acoustic emission) tests, confocal laser scanning microscopy (CLSM) and other physicochemical measurements. At each sampling, tissue specimens were soaked in mannitol solutions (0.0–0.9M) and puncture test, dimension changes and CLSM were used to identify degrees of turgidity present in osmotically manipulated pepper tissue. Pepper texture became crumbly with increased storage time due to softening and wilting processes. The Young's modulus, derived from the bending test using the single-edge notched bend geometry without notches decreased progressively during cold storage and resulted as the best mechanical parameter for measuring the loss of whole-tissue stiffness by both decreased cell wall stiffness and turgor pressure. Osmotic adjustment indicated that the pepper structure is extremely anisotropic, with the specimen's “average” relative thickness (RT) being the dimension change more affected. Incipient plasmolysis was evident in the highest mannitol concentration (0.9M), therefore, the turgor pressure of nonsoaked tissue could not be inferred. However, significant correlations were found between RT and puncture parameters such as initial slope, initial and final distances, and the number of flesh and skin force peaks, which depended on the dilation or shrinkage caused by the osmotic adjustment. During storage, soaked tissues had lower crunchy texture than nonsoaked, reflecting that cell wall stiffness plays a more significant role in determining pepper crunchiness than cell turgor pressure.     

Instrumental evaluation of defective texture in dry-cured hams

In the first experiment, the effect of the stress relaxation time on texture evaluation of biceps femoris (BF) muscle from dry-cured hams was studied. The specimens were compressed to 25% of their original height and the crosshead speed was 5mm/s. The force decay versus time was recorded and Peleg's model was fitted with different relaxation times. Whatever relaxation time was used, Peleg's model did not describe simultaneously the initial fall of force and the asymptotic tendency of force decay correctly. The initial force and force decay at 2s and at 90s are proposed to assess texture in dry-cured ham. In the second experiment, stress relaxation (SR) and texture profile analysis (TPA) tests were performed on BF and semimembranosus (SM) muscles of 10 hams with abnormal softness and 10 hams with normal texture, at different assay conditions: sample temperature (4°C or 20°C); compression crosshead speed (1mm/s or 10mm/s). The instrumental texture test and the assay conditions that detected defective textures better depended on the muscle considered: for BF muscle the SR test at 4°C and at 1mm/s and for SM muscle the TPA test at 10mm/s at both 4°C or 20°C.     

The instrumental texture profile analysis revisited

Although innovative at the time of their inception, all the historic and extant instrumental texture profile analysis (TPA) versions have serious methodological flaws. Their measured and calculated parameters, for example, “hardness,” “brittleness,” and “cohesiveness,” bear only a remote relationship to the same properties as understood in material science and other disciplines. The TPA parameters are supposedly objective measures of the tested food's textural attributes. But because they are all specimen size‐dependent, they cannot be considered intensive material properties. Also, because the arbitrary test conditions, notably the specimen and probe's geometries and the set deformation level significantly affect the TPA parameters' magnitudes, assigning them textural term leads to logical inconsistencies, making their relationship to the food's actual properties even more difficult to establish. It is doubtful that the instrumental TPA parameters indeed describe the same properties in different foods and sometimes even within the same food, as in ripening juicy fruits and certain soft cheeses. It is proposed that the TPA parameters currently in use be replaced by a list of mechanical and other physical properties determined by testing methods recognized by material scientists, such as “yield stress,” “strain at failure,” “stiffness,” and “toughness,” perhaps supplemented by a quantitative measure of “juiciness” and/or the acoustic signature's features, especially developed for the particular food. It is also proposed that instead of correlating such intensive material properties with sensory evaluations described by a predetermined sensory vocabulary, they should be used to study the distribution or spectrum of humans' verbal responses, expressed in their own chosen terms.     

RELATIONSHIPS BETWEEN SENSORY CRISPNESS AND OTHER SENSORY AND INSTRUMENTAL PARAMETERS1

Twenty subjects judged the crispness, loudness, and firmness of sixteen food samples by both biting and chewing and by only biting the foods. These subjects also scored the foods for thirteen textural qualities. Instrumental measures of slope, peak force, and deformation to fracture were obtained for the sixteen foods from a snap test at four deformation rates. Whether a subject judged an attribute by the bite or the bite and chew technique made little or no difference in the sensory judgments. Crispness appeared to be very closely related to loudness and less closely related to firmness. Loudness of the chewing sounds was more closely related to crispness than to firmness. Of the sensory qualities studied, loud, snap, and crackly were the three most closely related to crispness. Of the instrumental parameters Young's Modulus generally had the highest correlation with the crispness of all foods and peak force generally had the highest correlation with firmness. Deformation rate had minimal effects on measures of flexure or peak force, but its effects on Young's Modulus were frequently large and irregular. A vibrotactile-acoustical hypothesis for crispness is proposed.     

TEXTURE OF CULTURED GILTHEAD SEA BREAM (SPARUS AURATA): INSTRUMENTAL AND SENSORY MEASUREMENT

The texture of twelve samples of farmed gilthead sea bream (Sparus aurata) from experimental and commercial cultures, fresh and frozen, was determined by instrumental texture profile analysis (TPA) of whole raw fish and by sensory analysis of the corresponding cooked fish fillets. Average values of TPA hardness and chewiness were higher for fresh samples (78.0 N and 41.9 N, respectively) than for frozen and thawed samples (43.5 N and 21.5 N, respectively). The effect of freezing on springiness and cohesiveness values was different depending on the sample (a significant sample × freezing interaction). By sensory analysis, higher firmness, chewiness and fibrousness, and less juiciness were detected in frozen samples. Only one sample was perceived as less chewy, less fibrous and more juicy than the rest, and that corresponded to the smallest (less mature) fish. High percentages of the variability of sensory firmness (92%), chewiness (91%) or juiciness (85%) were explained by several of the TPA parameters measured on the raw whole fish using a fast nondestructive test.     

Texture changes in bolus to the “point of swallow” - fracture toughness and back extrusion to test start and end points

The change in texture of a food bolus during chewing, from first bite to swallow, is dramatic for solid foods and a variety of analytical techniques are required to quantify the texture at any given point in the chewing cycle. The objective of the work presented in this paper is to develop mechanical and rheological tests relevant to a model food, allowing the texture of the bolus to be quantified at first bite, and when masticated to the point of swallowing. This paper presents one aspect of the “Food Structure Platform” programme, a multi-disciplinary New Zealand programme investigating the influence of structure on the textural attributes of solid foods. The programme team is developing model foods and novel techniques to test their mechanical and rheological properties.The first model food developed by the Food Structure Platform is a biscuit with a well defined range of hardness within one basic recipe. This was tested in 3-point bending to determine fracture stress and relate that to texture perceived on first bite. The biscuit samples were also masticated to the point immediately prior to where the subject would have normally swallowed then expectorated for rheological testing. Modified TPA and back extrusion, based on a cup and piston test piece, were used to test the rheological properties of the bolus from each of the biscuit models. Good correlations were found with fracture stress of the biscuit and sensory hardness for first bite. At the point of swallow the bolus had a consistent cohesiveness and saliva content irrespective of starting texture, whilst the hardness and adhesiveness was affected by starting texture/recipe.     

不同硬度奶酪的质构及流变特性比较

针对3 种不同奶酪样品(硬质、半硬质、软质)对其进行成分分析、质构特征参数(应力松弛、破断)测定、质地剖面分析(TPA)、感官评定及动态流变特性实验。结果表明：奶酪样品硬度的不同对其质构特征和动态流变参数有明显影响;硬质奶酪具有弹力大的特点;黏聚性小、破断强度大,软质奶酪具有弹力小、黏聚性大、破断强度小的特点;在整个频率扫描范围内,随着硬度的下降,样品的贮藏模量(G′)、损失模量(G″)、动力学黏度( η′)都呈下降趋势。     

Axial Compression Properties of Kamaboko

Kamaboko, gelled seafood product from frozen surimi, has distinctive textural properties. Characterization of those properties, using an integrated approach to Theological studies, was accomplished by means of an instrumental texture profile analysis and evaluation of resultant stress-strain relationships. The material had near-ideal area expansion even at compressions of 60% while retaining its highly elastic texture. Apparently the product did not yield through 80% compression. Hardness of the kamaboko at 80% compression was characterized by a local maximum at 37.5°C which may have been related to processing temperature of the initial surimi gel-set used in a double-gel-set procedure. Evaluation of stress-strain relationships confirmed the incompressible nature of the gel and showed relatively slight variations between the Young's modulus and the deformability modulus. The elastic limit of the kamaboko increased significantly as temperature increased from 25 to 50°C.     

模拟超市销售期间圣女果质构特性变化的研究

采用TPA(texture profile analysis)测试法和感官评价相结合的方法,测定模拟超市销售期间圣女果货架期质构特性和品质变化指标,并对其相关性进行分析。结果表明,TPA测试圣女果的各项质构参数能够在不同方面反映圣女果在货架期间的品质变化特性,货架期4d是圣女果质构特性及其它品质变化的拐点,货架期6d时所有质构特性及品质会急剧下降。质构参数硬度与感官评分呈极显著正相关(P<0.01),咀嚼性与感官评分呈显著正相关(P<0.05),表明主要质构参数测定可用于预测圣女果在此条件下的品质变化。     

Effect of cream homogenization on textural characteristics of low-fat Iranian White cheese

The effects of cream homogenization of cheese making milk on textural and sensory characteristics of Iranian White cheese were studied. Cream was homogenized in a two-stage homogenizer at 6.0/2.5 or 9.0/2.5 MPa. Cheese samples were analyzed for rheological parameters (uniaxial compression and small amplitude oscillatory shear), meltability, microstructure, and sensory characteristics. Cream homogenization increased fat content leading to increased meltability. This effect increased as the homogenization pressure increased. The values of storage modulus, stress at fracture and Young's modulus of elasticity for cheeses from homogenized treatments were lower than those of unhomogenized cheese. Cream homogenization at 6.0/2.5 MPa effectively improved the textural, functional and sensory characteristics and enhanced the yield of low-fat Iranian White cheese. This cheese had the lowest values of storage modulus and stress at fracture, probably due to the high number of small, evenly dispersed fat globules in microstructure and especially its lower protein content. Cheeses with homogenized cream had improved texture, flavor and appearance.     

PREDICTING SENSORY COHESIVENESS, HARDNESS AND SPRINGINESS OF SOLID FOODS FROM INSTRUMENTAL MEASUREMENTS

ABSTRACT

The sensory evaluation of cohesiveness, hardness and springiness of 15 solid food samples was performed by eight trained assessors. The rheologic response of the 15 samples was estimated by performing cyclic compression tests and stress–relaxation tests. From the force–deformation curves of the first two cycles of the compression test, texture profile analysis parameters related to cohesiveness, hardness and springiness were calculated. Young's modulus (E), strain (d_i) and stress (s_i) at peak as well as irrecoverable strain (r_i) and irrecoverable work (L_i) were monitored during the first five cycles. From the stress–relaxation response, Peleg's linearization model parameters, K₁ and K₂, were estimated by best‐fit regression. These parameters were used for predicting sensory attributes. Hardness and springiness were both accurately predicted by rheologic properties, while cohesiveness prediction was less representative.

PRACTICAL APPLICATIONS

This study contributes to enhance the knowledge in the research area of sensory instrumental correlation. Also, the research allows to better understanding that no single instrument is able to measure all texture attributes adequately. In fact, the results demonstrate that both stress–relaxation and cyclic compression tests need to be performed for the correct prediction of sensory responses.