TENSIPRESSER PRECISION IN MEASURING COOKED RICE ADHESIVENESS

Precision in measuring cooked rice adhesiveness was studied using a Tensipresser and the "full cup" method. To determine the optimum adhesiveness parameter, 14 samples each from rice harvests in 1992 and 1993 were used. Out of the 42 parameters derived from a force-distance curve, the ratio of cumulative adhesiveness to cumulative hardness,     was used as the optimum because of its high correlation (r >0.9) with sensory adhesiveness, high precision (mean coefficient of variation (CV) of 14 samples <15% and maximum CV of 14 samples <25 %), and high resolution based on Kruskal-Wallis test statistic H. For parameter     , the maximum CV decreased with the increasing number of bites, and statistic H indicated that increasing the number of bites from 1 to 5 increased resolution, but bites exceeding 5 did not clearly do so.     

EFFECTS OF PUREE PROCESSING METHODS ON THE TEXTURAL CHARACTERISTICS OF AN ALGINATE- TEXTURIZED SWEET POTATO PRODUCT1

The objective was to determine the effect of sweet potato (SP) puree preparation methods on the properties of texturized SP products. The treatments were separated into two main types in which sliced SPs were cooked prior to puree preparation, or purees were prepared by grinding raw roots, followed by heat processing using steam injection. Purees from each treatment were texturized into cylinders 12.7 cm long and 5.5 cm in diameter, using an alginate-calcium system, and frozen. We found that cooked purees prepared by steam injection of raw purees had higher viscosities than did purees made from cooked SP. Texture Profile Analysis (TPA) revealed that texturized product made from SP cooked before puree preparation was the most fracturable and least springy of the texturized products. Sensory panelists did not express apreference for texturized product from any of the treatments, but 23% of the panelists noted a grainy texture and/or raw root aroma in products prepared by steam injection of raw purees. In view of these observations and the fact that puree preparation from cooked SP is the simplest process, this process appears to be the best for this type of texturized SP product.     

TEXTURE MEASUREMENT OF COOKED RICE KERNELS USING THE MULTIPLE-POINT MENSURATION METHOD 1

A new modification of Texture Profile Analysis, a two-point mensuration method, was shown to give better differentiation between different types of cooked rice. The method involves compressing single rice kernels 50% and 90% at 240 mm/mm. Ratios of values obtained at the two compression depths were better reflectors of the texture of rice as affected by the amount of water used in cooking and by rice variety (glutinous versus non-glutinous). Data are also presented showing how hardness, cohesiveness, adhesiveness and springiness of rice vary with compression or biting depths and with the position of the kernel in the cooker. The ratio of adhesiveness to hardness at 50% compression and the ratio of adhesiveness to hardness between the two compressions were the most useful indices.; in final form February 18, 1981     

EFFECT OF ULTIMATE pH UPON THE WATER-HOLDING CAPACITY AND TENDERNESS OF MUTTON

SUMMARY— Ultimate pH values in the musculature of sheep ranging from 5.6–7.0 have been obtained by using pre-slaughter injections of epinephrine. A high speed centrifugal method was used to measure the water-holding capacity of raw M. semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF). Results showed a high correlation with ultimate pH. Cooking losses end the amounts of centrifugally expressed juice were determined for the SM and BF cooked for 1 hr at either 65°C or 90°C. Cooking losses at 65°C decreased linearly with increasing pH while the losses at 90°C showed little change up to o raw meat pH of ca. 5.9, then decreased linearly with increasing pH. The amount of juice centrifugally expressed from the cooked meat, which has a high positive correlations with organoleptic juiciness, increased linearly with pH. Tenderness of the cooked SM and BF muscles was measured using o Warner-Bratzler shearing device and an Instron Universal Testing Machine: both gave high objective-subjective correlations. Instron measurements have high negative linear correlations with ultimate pH for both the 65°C and 90°C cooked samples. Hardness of these muscles, cooked at 65°C or 90°C. decreased approximately three-fold as ultimate pH increased from 5.6–6.9. Results obtained using the Warner-Bratzler device showed linear regressions with a significant quadratic component for one muscle at both 65°C and 90°C.     

A comparison between two methods (Warner-Bratzler and texture profile analysis) for testing either raw meat or cooked meat

Two methods for assessing texture characteristics of meat (Warner-Bratzler (WB) - and texture profile analysis (TPA)), both performed either on raw or on cooked meat, were tested in 96 samples of m. longissimus dorsi muscle of eight heifers and eight bulls, aged 1, 3 or 6 days post-mortem. A sensory analysis was also performed on 96 samples. Sensory variates were predicted by instrumental variates as follows: hardness was better predicted by TPA than by WB; springiness was only predicted by WB; juiciness was only significantly predicted by TPA; greasiness was always poorly predicted, but the prediction was better with TPA, and the number of chewings was also better predicted with TPA. Results suggested the convenience of performing a TPA for assessing meat texture as, in cooked meat, only TPA furnished highly significant correlations for hardness, for juiciness and for the number of chewings. Although WB could predict hardness and springiness, only the equation for the prediction of the number of chewings was useful (r(2)=0.171, P<0.004). It seems that texture parameters, assessed by a TPA and performed on cooked meat, are the best predictors of sensory texture in bovine meat.     

谷蛋白溶涨指数与面制食品质量控制

选用27个中国小麦样品，研究了谷蛋白溶涨指数对于评价中国白盐面条品质评价的适用性。谷蛋白溶涨指数与面带长度呈极显著负相关，与面带厚度呈极显著正相关。谷蛋白溶涨指数各时间(0min，5min，20min)与面条最佳煮面时间、鲜面条最大拉伸阻力、拉伸能量、拉伸长度均呈极显著正相关(除SIGO与最佳煮面时间呈显著正相关)；谷蛋白溶涨指数与可溶性谷蛋白、不溶性谷蛋白含量、面筋指数及蛋白质含量呈极显著正相关；谷蛋白溶涨指数与煮后面条表面韧性呈显著或极显著负相关，与剪切韧性呈显著正相关。谷蛋白溶涨指数可以作为一种品质指标控制面制食品的质量。     

米饭质构特性测定方法的研究(Ⅰ)

用不同品质的大米,参照GB/T 15682—2008的米饭样品制备方法制作米饭样品,并利用质构测试仪采用TPA模式对米饭样品的质构特性进行测定,通过试验考察米饭样品制作方法及米饭质构测试条件对测定值及其稳定性的影响。结果表明:在本研究的炊饭和米饭样品制作条件下,探头尺寸大小(形式)对质构测定值是否反映大米食味品质特征差异有较大的影响,电饭煲炊饭和铝盒炊饭方法用Φ25.4 mm圆球探头进行质构测定时,其硬度和黏着性测定值都能够较好地反映不同品质大米的差异程度,适合作为米饭质构测定方法采用。其中硬度值的变异系数较小,精确性较好。     

Assessment of the previous heat treatment given to meat products in the temperature range 40°–90°C. Part 2: Differential scanning calorimetry, a preliminary study

Differential scanning calorimetry (DSC) was examined as a potential method for determination of the previous heat treatment of a meat product. Samples of beef ( M. longissimus dorsi and M. semimembranosus ) were given a known heat treatment using a thermostatically controlled waterbath or the DSC instrument itself. Analysis in the DSC was then carried out over the temperature range 22–97°C at a heating rate of 10°/min. Raw beef was found to produce a three peak thermogram within the temperature range 45–90°C with peak maximum at 55, 66 and 79°C. As heat treatment is applied the peaks gradually disappear and variations in the cooked sample pattern can be related to the previously applied treatment. It appears that both the temperature and duration of heat treatment are important to the degree of denaturation and therefore the thermogram pattern. A promising correlation exists between maximum heat treatment temperature and the onset of denaturation obtained by DSC analysis, whilst the effect of duration of heat treatment is reflected in the area of the thermogram. It appears from the resultant thermograms that it may be possible to obtain an indication of the temperature and possibly duration of the previous heat treatment.     

INTERNATIONAL COOPERATIVE COMPARISON OF INSTRUMENT METHODS FOR COOKED RICE TEXTURE

The texture of 10 milled rices cooked by a standardized method in excess water was measured in 11 laboratories using various instrument methods that had been developed specifically for national samples. The samples selected represented a wide range of rice textures. Instrument indexes for hardness and stickiness of cooked rice generally were more sensitive than the corresponding taste panel scores in discriminating among the 10 cooked rice samples. Instrument indexes for hardness correlated positively among each other as did those for stickiness. Most hardness indexes showed significant negative correlation with stickiness indexes. Most hardness indexes were positively correlated with amylose content whereas stickiness indexes were negatively correlated with amylose content. The continued use of amylose content as an index of eating quality in a rice breeding program is justified.     

The contribution of dietary nicotine and dietary cotinine to salivary cotinine levels as a nicotine biomarker

Dietary nicotine, as a source of nicotine biomarkers such as salivary cotinine, has been a controversial topic, mainly because of limited published data on nicotine in foods. Recently, a sample preparation method for nicotine in foods and an analytical method, based on gas chromatography with mass spectrometric detection, were developed and validated in our laboratory. Nicotine was determined in fresh, cooked and processed foods of the Solanaceae family. In this study we have furthered this work to investigate the presence of cotinine in these vegetables, using GC–MS and HPLC–MS as independent alternative analytical techniques. A large number of samples was investigated, but cotinine was not detected in any of the samples, although very high sensitivity could be achieved. Based on the results, we report a Monte Carlo simulation of salivary cotinine levels obtained utilising dietary nicotine, food consumption data, and the variance in these parameters. In this estimate, a mean salivary cotinine concentration of 0.022 ng ml⁻¹ is predicted from dietary sources. This level is below the limit of detection for traditional analytical methods, but perhaps not for newly-developed methods.     

10种生、熟蔬菜中Vc含量及抗氧化性对比研究

通过用钼酸铵分光光度法测定生、熟青椒、尖椒、洋葱、胡萝卜、豆角、西红柿、茄子、苦瓜、芹菜、卷心菜10种蔬菜中Vc的含量。其反应原理是在SO42-离子存在的条件下,选用钼酸铵作为显色剂,利用反应生成的钼蓝,Vc在波长730nm处有强吸收,其浓度在2～22μg/mL范围内与吸收值呈良好的线性关系,该法简单、快速、准确测定Vc含量。结果表明,10种蔬菜在生熟两种情况时Vc含量有明显的变化,生蔬菜中Vc含量普遍高于相应熟蔬菜。最后,用DPPH法对比研究生熟蔬菜的抗氧化性,实验进一步证实Vc含量与其抗氧化性二者呈现一定的量效关系。     

储粮生物危害检测仪的研制

基于生物代谢的原理,采用CO2和湿度传感技术,研制出一种新型的储粮生物危害早期检测仪器。该仪器由样本采集、检测、结果显示及保存等部分组成,并带有人工智能判定系统。选用环境样本和两个被感染玉米样品对仪器进行了稳定性检验,CO2和湿度(n=8)相对标准偏差(RSD%)范围分别为1.01%~2.31%和1.39%~3.23%。采用本仪器与危害真菌孢子计数法,对不同水分的小麦、稻谷和玉米样品储藏真菌生长与CO2浓度、湿度变化进行了研究,结果表明,粮食中湿度变化主要与粮食的水分有关,其相关性分别为:小麦r2=0.997 98、稻谷r2=0.919 24、玉米r2=0.986 74;样品中CO2浓度的变化主要与真菌生长有关,其相关性分别为:小麦r2=0.968 36、稻谷r2=0.983 84、玉米r2=0.979 76。另外,以平房仓小麦储藏为例,进行了应用性实验。结果表明,本仪器用于储粮真菌危害的早期检测是可行的。     

More about fibre friction and its measurements

Unfortunately, the classical empirical friction laws do not hold true for fibrous and viscoelastic materials comprising most of the textile fibres. In the second half of the twentieth century, fibre surfaces have been studied by many distinguished scientists who were able to complete numerous researches for the frictional characteristics of different types of fibres. Most of the researchers have aimed to develop a new test method and a test device that can be used to measure the frictional characteristics of fibres quickly, accurately and easily in their studies. Unfortunately, there is not a standard test method or a test device for the measurement of textile fibres' friction properties. For today's competitive marketing, the instrument for fibre testing must be very fast and accurate; otherwise, it will not be useful for commercial purposes. For example, hundreds of thousands of cotton bales should be tested within a very short period of time in terms of the length, colour and trash content of the cotton bales. Without having the data describing the properties of cotton fibres, cotton bales cannot be sold commercially in most of the countries. Therefore, it is an important factor that the fibre-testing instrument should be fast and accurate. Most of the properties of cotton fibres can be assessed by using a HVI fibre-testing instrument. In this review, the historical perspective of fibre friction studies has been demonstrated with the fibre friction measurement-testing devices.     

A note on the nature of the haematin pigments present in freeze dried and cooked beef

Analysis of the reflectance spectra of beef samples treated to contain all the haemoproteins in one pigment form indicated that little or no change in the haematin environment occurs on freeze drying fresh, oxymyoglobin-rich meat or cooked meat. Dehydration of metmyoglobin in meat results in the water molecule at the sixth coordination site being replaced by a protein-bound ligand. On rehydration, this ligand may be replaced by water to reform metmyoglobin, but the degree of conversion depends on the rate of rehydration. The spectral similarity between cooked and freeze dried, oxidised meat indicates that the haematin environments are similar. It is suggested that in these meats the predominant pigments are di-imidazole complexes.     

猪肉质构的仪器测定与感官评定之间的相关性分析

以熟肉为研究对象,比较感官评定和两种仪器测定方法(剪切法和质构剖面分析)之间的差异和关联性。结果表明:剪切力与感官评定的硬度、多汁性呈显著相关性(r=0．73、-0．71);质构剖面分析硬度与感官评定的硬度相关性显著(r=0．81),质构剖面分析的粘聚性与感官评定的弹性、多汁性、油性分别呈显著相关性(r=-0．79、-0．67、-0．81)。通过建立仪器分析与感官评定间的数学模型,本实验提示质构剖面分析更能全面预测猪肉感官品质。进一步的实验参数验证了质构剖面分析回归方程预测的准确性。     

Human oral processing and texture profile analysis parameters: Bridging the gap between the sensory evaluation and the instrumental measurements

Studies in food oral processing are becoming increasingly important with the advent of the aged society. The food oral processing model of Hutchings and Lillford (Journal of Texture Studies, 19, 1988, 103–115) describes the structural breakdown and lubrication of ingested food before the swallowing stage, and has been revisited in the present article. The instrumental technique texture profile analysis (TPA) purports to mimic the first two bites of mastication and its ease of use has lured some researchers to use it without a critical eye. In this article, we consider inconsistencies in the Hutchings and Lillford model with the hope that it might be further refined. With regard to TPA we question the validity of the data generated and urge authors caution before they publish results from the test protocol. If results are published then the x‐axis should be viewed as deformation or strain, and not time. Hardness should be represented by the breaking stress. Adhesiveness should be measured at a medium strain taking into account the surface properties of the plunger. The ratio of the energy estimated by the area under the curve obtained from the second and the first bites (A₂/A₁) should be called recoverability and not cohesiveness.     

Texture properties of formulated wheat doughs Relationships with dough and bread technological quality

Texture properties of wheat doughs were determined with a texturometer by using texture profile analysis (TPA) as well as Chen and Hoseney methodologies. The time elapsed between two compressions and strain were optimized so that meaningful values were obtained for TPA. Single effects and interactions between flour type, the breadmaking process and anti-staling additives (i.?e. monoglycerides, diacetyl tartaric ester of monoglycerides, sodium stearoyl lactylate, carboxymethylcellulose and hydroxypropylmethylcellulose) on dough texture properties (i.?e. springiness, resilience, hardness, cohesiveness, adhesiveness, chewiness, gumminess and stickiness) were estimated. The breadmaking process and addition of hydrocolloids had the most important effects and interactions on TPA. Hydrocolloids and α-amylase increased dough stickiness. Dough cohesiveness was a good predictive parameter of bread quality. Water content, acidity values and gluten quality were the main factors determining the texture properties of dough.     

米饭质构特性测定方法的研究(Ⅱ)——米饭样品放置时间、环境温度对硬度值的影响

用不同品质的大米,参照GB/T 15682—2008的米饭样品制备方法制作米饭样品,并利用质构测试仪采用TPA模式对米饭样品的质构特性进行测定试验,探讨了米饭质构测定值的分散特征及米饭样品放置时间与测试环境温度对测定值的影响。用电饭煲炊饭和米饭样品预压8 mm方法制作米饭样品并用Φ25.4mm圆球探头进行的多次重复试验结果表明:硬度值的稳定性和精确性明显优于黏着性值,适宜将硬度值作为米饭质构特性测定的主要考察指标。结果还表明:随着米饭放置时间的延长,籼米米饭硬度值逐渐减小的趋势明显,粳米米饭在放置时间12 h范围内有硬度值缓慢增大的总体趋势;米饭制作、放置和测定过程的温度对米饭硬度值有较大影响,建议在进行米饭质构(硬度)测定时应当保持米饭制作、放置和测定全过程的温度恒定。     

Characterization of O/W model system meat emulsions using shear creep and creep recovery tests based on mechanical simulation models and their correlation with texture profile analysis (TPA) parameters

The effects of different oil and temperature levels on the viscoelastic behavior of O/W model system meat emulsions were assessed using creep and creep recovery tests. The viscoelastic behavior of such emulsions was characterized using the Burgers model parameters. In addition, texture profile analysis (TPA) of cooked meat emulsions was carried out to find a possible relationship between the creep and creep recovery data and TPA parameters. The final percentage recovery of the emulsions remarkably increased with oil content, but decreased with temperature level. Significant correlations among the creep-recovery data and TPA parameters were observed, this enabling meat processor to predict TPA parameters by resorting to shorter and less material consuming creep and creep recovery tests.     

Time-resolved characterization of diesel particulate emissions. 2. Instruments for elemental and organic carbon measurements

The measurement of elemental carbon (EC) and organic carbon (OC) mass for particles emitted by diesel vehicles is currently accomplished using particle collection on filters, followed by analysis using the thermal/optical reflectance carbon analysis method (TOR) or one of its variations. Such filter methods limit time resolution to a minimum of several minutes, making it impossible to study emissions during transient operating conditions. Testing of five different measurement methods has demonstrated that fast response measurement of diesel exhaust particulate EC and OC concentrations, consistent with TOR filter measurements, is feasible using existing technology. EC mass concentrations are best measured through determination of particulate light absorption with a photoacoustic instrument or determination of light extinction with a smoke meter. The photoacoustic instrument has the better dynamic range and sensitivity, whereas the smoke meter is a simpler instrument. Fast response OC measurements cannot be made with any single instrument tested. However, a combination of real time weighing as implemented in the tapered element oscillating microbalance with the photoacoustic instrument has been shown to be capable of determining OC concentrations with good time response. The addition of a nephelometer to the OC measurement could potentially improve time resolution, freedom from interferences, and sensitivity.