冷却猪肉新鲜度的色差快速分析评价方法

为了得到冷却猪肉新鲜度的变化规律,本研究以冷却猪肉里脊部分为研究对象,进行球蛋白沉淀实验、感官评价、pH值、水分含量、肉浸液以及肌肉表面颜色值测定。结果表明：球蛋白沉淀实验、pH值能够较好地反应肉品新鲜度的变化,色差分析符合一定的规律：肌肉表面色差测定中,20℃条件下,a*变化与贮藏时间显著相关(P＜0.05),L*变化显著(P＜0.05);4℃条件下,b*、C变化与贮藏时间极显著相关(P＜0.01),L*值与pH值极显著相关(P＜0.01);对于肉浸液,L*、b*、C、ΔE*均发生显著性变化(P＜0.05),20℃条件下L*、b*、C、ΔE*与贮藏时间和pH值显著相关(P＜0.05),而4℃条件下,L*、C、ΔE*与贮藏时间显著相关(P＜0.05),L*、a*、b*、C、ΔE*值与pH值极显著相关(P＜0.01);冷链过程中,当L*高于48.73、a*高于4.72、b*高于9.18时可认定冷却肉为新鲜肉。     

果胶改善玉米淀粉影响辣椒红在调理肉制品中呈色效果的研究

为改善玉米淀粉对辣椒红在调理肉制品中呈色的不利影响,研究了玉米淀粉、果胶和辣椒红不同浓度对体系颜色影响的特性。采用均匀设计优化了三种成分的浓度,使用偏最小二乘二次多项式进行数据回归分析,建立了以玉米淀粉、辣椒红和果胶浓度为自变量,亮度L*、红绿度a*、黄蓝度b*、色相h、总色差ΔE和散射率为因变量的预测模型。结果表明,该预测模型精度较高,最优呈色效果时各个因素组合为,玉米淀粉浓度5.37%,果胶浓度2.90%,辣椒红浓度0.27%。此时各色差指标为,L* 49.6024,a* 39.7159,b* 40.0236,h 44.6671,ΔE 10.3461,散射率0.2063。经实际体系验证该最优呈色条件能够有效改善玉米淀粉-辣椒红体系在调理肉制品中的呈色效果。本文通过预测模型筛选得到的最优呈色效果的原料配比能够有效的改善玉米淀粉-辣椒红体系的呈色效果。     

Color and Volatile Analysis of Peanuts Roasted Using Oven and Microwave Technologies

Roasted peanut color and volatiles were evaluated for different time and temperature combinations of roasting. Raw peanuts were oven roasted at 135 to 204 °C, microwave roasted for 1 to 3 min, or combination roasted by microwave and oven roasting for various times and temperatures. Volatiles were measured using selected ion flow tube mass spectrometry. L* values were used to categorize peanuts as under‐roasted, ideally roasted, and over‐roasted. The total roasting time in order to achieve ideal color was not shortened by most of the combination treatments compared to their oven roasted equivalents. Oven before microwave roasting compared to the reverse was found to significantly increase the L* value. Peanuts with the same color had different volatile levels. Hexanal concentrations decreased then increased with roasting. Pyrazine levels increased as roasting time increased, although oven at 177 °C treatments had the highest and microwave treatments had the lowest levels. Volatile levels generally increased as roasting time or temperature increased. Oven 177 °C for 15 min generally had the highest level of volatiles among the roasting treatments tested. Soft independent modeling of class analogies based on volatile levels showed that raw peanuts were the most different, commercial samples were the most similar to each other, and oven, microwave, and combination roasting were all similar in volatile profile.     

基于计算机视觉的鲶鱼肉色泽测定系统

采用色差计与计算机视觉系统(computer vision system,CVS)两种方法分别测定鲶鱼(Clarias leather)冰藏18 d期间鱼肉的色泽变化,探讨CVS方法测定鱼肉色泽(L*、a*、b*)的可行性。结果表明,两种方法所得的冰藏期间鲶鱼肉色泽变化趋势相同,且所得的总色差(ΔE值)基本相等。鱼肉冰藏期间明度(L*值)和ΔE值随着冰藏时间延长而逐渐升高(P0.05);红度(a*值)在前3 d缓慢升高,之后显著下降(P0.05);黄度(b*值)无显著性变化(P0.05)。通过色差计测量值对CVS测量值进行校正并验证可知,其校正值与色差计测量值无显著性差异(P0.05),且二者L*、a*、b*值的线性相关系数为0.89~0.97,表明CVS测量值经校正后,能准确地检测出冰藏期间鲶鱼肉的色泽变化,从而实现鱼肉色泽的快速测定。     

Influence of seed roasting process on the changes in composition and quality of sesame (Sesame indicum) oil

The composition and quality changes of sesame oils prepared at different roasting temperatures (180–260°C) from sesame seed were evaluated and compared with an unroasted oil sample. There were no apparent differences in characteristics, such as acid value, iodine value, saponification value and refractive index, of sesame oils prepared at a roasting temperature between 180 and 220°C. The colour units and total polar content of oils increased in relation to an increase in roasting temperature. The phospholipid content was reduced from 690 mg kg^?1 in unroasted oil to 0 mg kg^?1 in the oil prepared using a 260°C roasting temperature. The fatty acid content of the oil was reduced markedly, especially in oleic and linoleic acids, when the roasting temperature was over 220°C. The amounts of chlorophyll and sesamolin decreased with increasing roasting temperature. However, the highest level of sesamol and γ-tocopherol was found in oils prepared with a 200–220°C roasting temperature. The sesame oil prepared at a 200°C roasting temperature had the best flavour score when compared with the other samples.     

Kinetic of Color Changes in Almond (Akbadem Variety) During Roasting and Storage

In this research, the color change kinetics of the Akbadem variety during roasting and storage processes was investigated. The roasting process was carried out at three different temperatures (150, 160, and 170°C) and four different times 10, 20, 30, and 40 min. Then, roasted samples were separated in two groups and stored for 6 months in 4 and 22°C. All of the color parameters reactions during roasting and storage took place according to first order reaction kinetics. L- and hue angle-values tended to decrease linear significantly during roasting. The L-values of Akbadem samples roasted at 150, 160,and 170°C for 40 min was determined as 52.34 ± 2.53, 47.96 ± 1.35, and 43.17 ± 0.09, respectively. The highest Ea-value was determined on the L-value as 14.80 ± 4.26. The a, b, ΔE, metric chroma (C), and metric saturation (S) values increased during roasting. L-, C-, a-, b-, and S-values tended to decrease linear significantly during storage. The L-, a-, and b-values of Akbadem samples which were roasted at 170°C and stored at 4°C for 6 months were decreased from 43.17 ± 0.09, 14.25 ± 0.026, and 29.53 ± 0.06 to 34.91 ± 0.13, 10.06 ± 0.15, and 15.93 ± 0.12, respectively. According to sensory analysis, the panelists gave low scores as taste (1.9 ± 0.88), color (2.1 ± 0.57), and flavor (2.4 ± 0.7) for Akbadem samples roasted at 170°C for 40 min. ΔE was increased during storage Ea-values were decreased during roasting and storage at 4 and 22°C for 6 months.     

Effect of Starch Sources on Properties of Extrudates Containing DDGS

Various levels of DDGS (20, 40, and 60% wb) were blended with starch sources (cassava, corn, and potato), and other ingredients to produce an iso-nitrogenous feed (28% protein) at varied moisture contents (15, 20, and 25% wb). The feed blends were extruded in a single-screw extruder at a preset screw speed of 130 rpm (13.6 rad/s) with three temperatures profiles 90–100–100°C, 90–120–120°C, and 90–140–140°C. The effect of these variables on processing conditions (extruder torque and die pressure) and other extrudate properties (expansion ratio (ER), unit density (UD), color (L*, a*, and b*), sinking velocity (SV), water absorption, water solubility, and pellet durability indices (PDI)) were analyzed. For all the three starch extrudates, changing the levels of DDGS, feed moisture content, and extruder barrel temperature had a significant effect on SV, PDI, a*, and b* values at α = 0.05.     

Effects of Dielectric and Steam Heating Treatments on the Pre-Storage and Storage Color Characteristics of Pecan Kernels

Pecan kernels were subjected to steam conditioning and dielectric heating treatments and evaluated initially and during 16 wk of accelerated storage to determine temperature effects on color characteristics. Steam conditioning treatments, which raised kernel temperature to 93°C, caused significantly greater darkening of the kernels initially and during storage than did dielectric heating to 88, 136, and 156°C. Comparison of mean Hunter color values of stored dielectrically heat-treated kernels and kernels that were frozen and maintained as control samples showed a stabilizing influence on kernel darkening by these heat treatments. Lightness (L values) of the kernels was increased by dielectric heating, Hunter a values did not differ significantly from the control, and the hue (θ) of the kernels was increased only by the 156°C dielectric heating treatment.     

INSTRUMENTAL AND SENSORY EVALUATION OF TEXTURAL CHANGES DURING ROASTING OF CASHEW KERNELS

Textural changes in cashew kernels roasted in hot‐air oven at controlled temperatures in the range of 140–180C for 30–120 min were studied using both instrumental and sensory evaluations. The Kramer shear force decreased exponentially, whereas the color lightness index and the total color difference exhibited linear relationships with roasting time at all temperatures. The changes in sensory parameters such as acceptability, appearance and taste were adequately described by third‐degree polynomials. The optimum roasting conditions for cashew kernels based on hedonic sensory evaluations were determined to be 140C–33.3 min, 160C–11.2 min and 180C–5.7 min, and resulted in similar values of Kramer shear force and color lightness index estimated from the developed models. The instrumental measurements could be used for monitoring the roasting process to produce optimally roasted cashew kernels.     

Ohmic heating blanching of Agaricus bisporus mushroom: Effects on polyphenoloxidase inactivation kinetics,color, and texture

The effect of ohmic heating blanching (OHB) on the inactivation kinetics of polyphenol oxidase (PPO), color, and texture from Agaricus bisporus mushroom treated at different temperatures (67–90 °C) for 1 to 5 min was investigated in the present work. OHB and conventional blanching (CB) treatments were able to inactivate mushroom PPO. However, the inactivation kinetics results showed a lower energy activation (E_a) value during OHB (16.03 ± 1.34 KJmol-1) compared to conventional blanching (20.07 ± 1.85 KJmol-1). Significant differences were observed in color (L*, h° and ΔE) and mushroom texture between the blanching treatments. Nevertheless, both treatments caused minimal physicochemical changes. Therefore, OHB is a promising technology for mushroom blanching because it promotes PPO inactivation in less time and reduces the impact on the color and texture of mushrooms compared to CB.     

Colour in short-term thermo-mechanically densified veneer of various wood species

Effect of short-term thermo-mechanical (STTM) densification temperature and pressure on the surface colour of veneer of four wood species—alder (Alnus glutinosa Gaertn.), beech (Fagus sylvatica L.), birch (Betula verrucosa Ehrh.), and pine (Pinus sylvestris L.) as well as possible correlations among all determined colour parameters (L*, a*, b*, h, C* and ?E) were investigated. Veneer sheets were densified at temperatures of 100, 150 or 200 °C and pressures of 4, 8 or 12 MPa for 4 min. The results were compared with those of non-densified veneers. The colour change of the samples was evaluated by CIEL*a*b* and L*h*C* colour co-ordinate systems. The results indicated: the temperature and pressure of densification affected to a big extent the colour of the veneer samples, with the effect of densification temperature being more evident than that of pressure. After the densification process, the veneers darkened. Colour changes are most pronounced at the highest densification temperature of 200 °C and very small at the lower temperatures of 100 and 150 °C for all investigated wood species. The change in a* is more pronounced than the change in L* or b*. In general, alder and birch veneer samples are characterized by the highest values of total colour difference followed by pine and beech samples among the four species. The quadratic models can be used for the prediction of surface colour in the densification process. The results of this study indicate that it is possible to govern surface colouration of wood veneers during densification process on an industrial basis.     

Effects of seed roasting temperature and time on the quality characteristics of sesame (Sesamum indicum) oil

The quality characteristics and composition of sesame oils prepared at different roasting temperatures (160–250°C) from sesame seeds using a domestic electric oven were evaluated as compared to an unroasted oil sample: only minor increases (P<0·05) in characteristics, such as peroxide value, carbonyl value, anisidine value and thiobarbituric acid reactive substances, of sesame oils occurred in relation to increasing roasting temperature and time between 160 and 200°C, but colour units of oils increased markedly over a 220°C roasting temperature. Significant decreases (P<0·05) were observed in the amounts of triacylglycerols and phospholipids in the oils prepared using a 250°C roasting temperature. The amounts of γ-tocopherol and sesamin still remained over 80 and 90%, respectively, of the original levels after roasting at 250°C. In the oil prepared using a 250°C roasting temperature, sesamol was detected at 3370 mg per kg oil, but sesamolin was almost depleted after 25 min of roasting. Burning and bitter tastes were found in the oils prepared at roasting temperatures over 220°C. The results suggested that a high-quality product would be obtained by roasting for 25 min at 160 or 180°C, 15 min at 200°C and 5 min at 220°C when compared with the other samples. © 1997 SCI.     

黄玉米籽粒发育过程中类胡萝卜素与色泽的变化

利用C30柱及高效液相色谱-二极管阵列检测-大气压化学电离质谱（high performance liquid chromatographyatmospheric-diode array detection-atmospheric pressure chemical ionization-mass spectrometry,HPLC-DAD-APCI-MS）法,对黄玉米在籽粒形成期、乳熟期和蜡熟期主要类胡萝卜素进行定性、定量检测,研究籽粒中类胡萝卜素的积累规律,分析类胡萝卜素各组分与色泽之间的关系。结果表明：整个发育过程中,黄玉米籽粒总类胡萝卜素含量与色泽的变化趋势基本一致,随着成熟度的增加,总类胡萝卜素含量不断增加,籽粒逐渐变黄,其中乳熟期是类胡萝卜素积累的关键时期。各类胡萝卜素组分含量变化较大,花药黄质、玉米黄质、叶黄素、α-隐黄质和β-隐黄质含量总体呈上升趋势,而新黄质含量一直下降,α-胡萝卜素和β-胡萝卜素含量变化不显著。通过对类胡萝卜素含量与色泽的相关性分析发现,玉米黄质、花药黄质、α-隐黄质及β-隐黄质含量均与L*、a*、b*和C值成极显著或显著正相关,与H值成负相关。     

三种荞麦米储藏期品质动态变化研究

以通荞2号、赤甜1号和品甜2号三个品种的荞麦米为研究对象,开展80 d储藏期内色度、含水量、脂肪、蛋白质、淀粉、总黄酮、叶绿素、类胡萝卜素等品质变化规律研究。结果表明,随着储藏时间的推移,荞麦米的外观颜色发生劣变。总色差ΔE*、ΔL*和Δa*变化显著,Δb*无明显变化;含水量、总黄酮、叶绿素和类胡萝卜素含量显著降低;蛋白质含量缓慢增加,但不显著;脂肪和淀粉含量无明显变化。这些因素变化趋势与时间变化相关性各异,ΔE*、Δa*与时间极显著正相关(P<0.01),ΔL*与时间极显著(P<0.01)或显著(P<0.05)负相关;含水量、总黄酮、叶绿素和类胡萝卜素与时间显著性负相关(P<0.05);三个品种的蛋白质含量与时间的相关性不一致;淀粉和脂肪与时间无显著相关性(P>0.05)。品种对ΔE*、ΔL*、Δa*、含水量、脂肪、叶绿素、类胡萝卜素的变化程度显著影响,而对Δb*、蛋白质、淀粉、总黄酮影响很小。研究结果为提高储藏品质及延长货架期提供有力的参考依据。     

Evaluation of animal age and muscle type on beef log juice colour and residual GOT activity when cooked to target end-point temperature of 79.4 °C†

The effectiveness of the pink-juice test to determine 79.4 °C end-point temperature (EPT) of cooked beef logs was appraised. Logs made from five cuts of meat from three animal age groups were fabricated in triplicate to simulate products received at ports of entry and then cooked to EPTs of 78.0–81.8 °C. CIELAB L*, a*, b*, C and h ° values of internal surfaces of freshly sliced meat and pressed juices from samples were determined. Sensory ratings were made by six trained panelists to determine intensities of residual red color of the juices. Animal age and cut of meat had little effect on the CIELAB color values. Residual red color was apparent in all samples by both sensory and a* values analysis. Sensory ratings did not vary significantly (P < 0.05) by animal age or cut of meat. Average values of 3.2 (intensity range, 1–9) corresponded to an EPT slightly greater than 80 °C; absence of red color in the juices would therefore indicate an EPT in excess of the target temp of 79.4 °C. Residual glutamic-oxaloacetic transaminase activity (GOT) activity, used as a collateral test for EPT, ranged from 482.5 to 1641.8 SFU ml⁻¹ of juice and differed significantly by cut of meat (P < 0.05), but not by animal age. © 1999 Society of Chemical Industry     

Evolution of quality parameters of high pressure processing (HPP) pretreated albacore (Thunnus alalunga) during long-term frozen storage

The aim of this work was to study the application of high pressure processing (HPP) before freezing for maintaining as much as possible the fresh characteristics of albacore steaks after long-term storage. HPP treatments were applied at 200 MPa for 0–6 min. Then, samples were immediately frozen (−20 °C) and stored (−20 °C) for up to 12 months. Once thawed (4 °C; 24 h), weight losses, color, texture, lipid oxidation (TBARS) and salt-soluble protein content were analyzed.After 12 months of frozen storage, 200 MPa for 6 min minimized thawing loss inherent to freezing and frozen storage and decreased TBARS (53.9%) with respect to the control. However, it resulted in changes in color (higher L*, b* and ΔE values) and texture (higher adhesiveness and springiness) and decreased the salt-soluble protein content with respect to non-pretreated samples. Nevertheless, after cooking, there were no differences in color and texture between HPP pretreated fish and the controls.     

Effect of Storage on 5-Hydroxymethylfurfural (HMF) Formation and Color Change in Jams

In this study, the effects of storage temperature (10, 20, and 37°C) and time (0, 2, 4, and 6 months) on the HMF and color values in strawberry, cherry and apricot jams were studied. Results showed that the HMF and total color difference (ΔE) values of all jams were increased linearly with storage time and higher values were found at higher storage temperature. Kinetic model was applied to changes in HMF and ΔE. Changes in HMF and ΔE were explained using zero-order reaction kinetics and the dependence of the rate constant on temperature was described by the Arrhenius equation     

Optimization of roasting conditions according to antioxidant activity and sensory quality of coffee brews

Response surface methodology (RSM) was used to determine the optimal roasting temperature and roasting time of coffee beans used for preparing brews with high antioxidant activity and sensory quality. Green coffee beans (Coffea arabica L. cv. Colombia Organic Tamata) were roasted at temperatures ranging from 140 to 220°C for 2–10 min and were then brewed with dripping hot water. The effects of the roasting conditions on the browning index, antioxidant activity, color, aroma, taste, and overall acceptability of the coffee brewed from the bean were investigated using a second-order central composite design. The quality indicators except the taste were significantly affected by roasting temperature and time, tending to increase and then decrease with increasing roasting temperature and time. Superimposed contour plots indicated that the optimal roasting temperature was 182°C and optimal roasting time was 7 min.     

Roasting and Colouring Curves for Coffee Beans with Broad Time-Temperature Variations

The effects of time and temperature on change in bean colour and kinetics of coffee roasting covering pre-roasting and over-roasting condition were investigated. Arabica coffee beans (Colombia Excelso) were dried or roasted in an oven at constant temperatures (140, 180, 200, 220, 260, and 300 °C) to obtain the profiles of mass loss and colour change. Changes in roasting rate from the first stage (high rate) to the second (low rate) were found to occur at different levels of roast loss for different roasting temperatures. Roasting curves were obtained by normalising the data of mass reductions, which comprised solid and moisture, to the initial solid mass. Changes in bean colour were found to follow a certain path regardless of the roasting temperature, as shown by the characteristic colouring curve, and were less affected by the temperature compared to the roast loss. A method of predicting the bean colour during roasting was also presented by analysing the relationships among the L*, a* and b* values.     

EFFECT OF HOT WATER IMMERSION ON PEEL COLOR OF PEARS AND ON WHITE ROT CAUSED BY BOTRYOSPHAERIA BERENGERIANA

Abstract The effectiveness of hot water immersion (HWI) on peel color and the control of white rot caused by Botryosphaeria berengeriana on wound-inoculated European pears, cv. La-France, were investigated. After HWI at 40, 45, 48, 50, 52 and 54C for varying immersion periods, the pears were held at 20C, ≥ 90% RH (simulated retail conditions). The peel color (L*, a*, b*) was determined before and after HWI treatment. The dominant role of L* suggested that peel darkening was the major factor in color change of the HWI treated pears. The L* value of 54 was judged as the border line for acceptability and less than 51 resulted in browning. Similarly the critical points for a*, b*, chroma, hue and ΔE* were found to be −6, 34, 35, 100, and 8, respectively. Disease incidence recorded 7 days after treatment revealed that High Temperature Short Time (HTST) treatment of 54C for 3 min reduced incidence about 85% with good retention of color. Both temperature and immersion period are to be carefully selected to prolong shelf-life and retain the peel color quality of 'La-France'pears.