米茶茶汤呈色的动力学研究

以碎米为原料,经浸润、焙炒制得米茶。制作过程中会发生美拉德反应和焦糖化反应,生成色素物质,使米茶冲泡时其茶汤具有一定的色彩。用Lab表色法研究米茶在浸泡过程中,米茶制备工艺及茶汤浸泡时间对茶汤色彩特征的影响。结果表明：随浸泡时间延长,茶汤色彩由黄红色逐渐转向以黄色为主的较纯色彩,茶汤透明度下降。米茶茶汤的色彩形成符合指数模型。浸润工艺对茶汤色彩有影响,以料液比1:20(m/V)浸润10min后的大米制作的米茶,茶汤呈色快速,透明度较好,有利于增强黄色和色彩纯度,且色彩稳定性较好。     

Effect of processing conditions on the quality of naturally fermented Turkish sausages (sucuks)

Effects of temperature and different fat levels on the quality of Turkish sausages (sucuks) were studied during the ripening period. Sausage batters prepared at 10%, 20% and 30% fat levels were processed at 20-22 and 24-26 °C. A high ripening temperature and low fat level caused fast dehydration. Fat level affected water activity, colour, total viable and lactic acid bacteria counts of the sausages. Increasing fat content and ripening temperature resulted in high lightness (L*) and yellowness (b*) and low redness (a*) at the end of ripening. The sausages with 10% fat resulted in higher redness values. Growth of total viable and micrococci-staphylococci bacteria was affected by ripening temperature. Sausages ripened at 24-26 °C had a rapid increase in micrococci-staphylococci counts.     

Effect of ethanol on properties of extrudates enriched with high-fibre by-products

In this study, we produced snacks based on mixtures of corn grits enriched with ethyl alcohol and high-fibr by-products like potato pulp, as well as flaxseed, rosehip and apple pomace. The prepared mixtures were subjected to the extrusion at the following process parameters: temperature of section I – 130 °C, temperature of section II – 150 °C, temperature of section III – 170 °C and screw speed – 200 r.p.m. The presence of ethanol in the extruded mixture significantly improved mechanical properties and increased colour lightness of snacks. The highest scores were given in sensory analysis to control snacks, whereas among the enriched snacks – to these with apple pomace. The most negative effect on snacks assessment was attributed to the addition of flaxseed and rosehip pomace. Ethanol addition had a very beneficial effect on scores given during sensory analysis to colour, texture and structure attributes of the snacks.     

Analysis of acrylamide by LC-MS/MS and GC-MS in processed Japanese foods.

Acrylamide concentrations in processed foods (63 samples covering 31 product types) from Japan were analysed by LC-MS/MS and GC-MS methods. The limit of detection and limit of quantification of acrylamide were 0.2 ng x ml(-1) (6 fmol) and 0.8 ng x ml(-1) (22 fmol), respectively, by LC-MS/MS, and those of 2,3-dibromopropionamide derived from acrylamide were 12 ng x ml(-1) (52 fmol) and 40 ng x ml(-1) (170 fmol), respectively, by GC-MS. Repeatability given as RSD was <5 and <15% for the LC-MS/MS and GC-MS methods, respectively. High correlation (r(2) - 0.946) was observed between values obtained by the two methods. Most potato crisps and whole potato-based fried snacks showed acrylamide concentrations >1000 microg x kg(-1). The concentrations in non-whole potato-based snacks, rice crackers processed by grilling or frying, and candied sweet potatoes were lower compared with those in the potato crisps and the whole potato-based fried snacks. One of the whole potato-based fried snacks, however, showed low acrylamide concentration (<50 microg x kg(-1)) suggesting the formation of acrylamide is strongly influenced by processing conditions. Acrylamide concentrations in instant precooked noodles and won-tons were <100 microg x kg(-1) with only one exception. Roasted barley grains for 'Mugi-cha' tea contained 200-600 microg x kg(-1) acrylamide.     

A second mutant allele (V199I) at the PRKAG3 (RN) locus-II. Effect on colour characteristics of pork loin

Three alleles at the PRKAG3 (RN) locus that influence the glycogen content of pork were found to be segregating in Hampshire×Landrace crossbred pigs, RN(-), rn(+) as well as second mutant allele V 199I (here denoted rn*). The effect of these three alleles on ultimate pH, pigment content, internal reflectance (FOP), surface colour measured by tristimulus colorimetry (L*, a*, b*) and fractions of deoxymyoglobin (Mb), oxymyoglobin (MbO(2)) and metmyoglobin (MetMb) of pork loin was studied. Moreover, the effect of sex, entire male versus female pigs, on these traits was also analysed. The three PRKAG3 alleles affected ultimate pH, internal reflectance, colour and distribution of myoglobin derivatives of pork loin, while the pigment content was not influenced. Ultimate pH values of loins from the three genotypes were found to be in the order RN(-)/- genotypes rn(+)/rn(+) genotype=rn(+)/rn* genotype=rn*/rn* genotype. The RN(-) allele was dominant resulting in higher redness (a* value) and yellowness (b* value), while the rn* allele tended to result in lower redness and yellowness compared with the rn* allele. The RN(-) allele was dominant over the rn* allele in lightness (L* value) giving a lighter colour. Surface colour differences were mainly explained by differences in the distribution of the myoglobin derivatives. Finally, surface lightness was higher and pigment content, redness and fraction of MbO(2) lower in loin from entire males compared with females.     

Acrylamide in home-prepared roasted potatoes

Potato is one of the world's most widely grown tuber crop, in which starch is the predominant form of carbohydrates. Potatoes can be prepared in many ways: boiled, fried or roasted. Frying and roasting potatoes at high temperatures result in an appetizing crust, but at the same time acrylamide can form. In this study, the concentrations of the acrylamide precursors, asparagine and sugars, were determined in five different Swedish-grown potato varieties, together with the acrylamide content after typical home-cooking procedures; oven-roasting of potato wedges and pan-frying of cubes of boiled potatoes. Pan-frying of boiled potato cubes resulted in higher levels of acrylamide (530-1100 microg/kg) than in the wedges (140-250 microg/kg). Blanching combined with a shorter roasting time was shown to be an efficient way of reducing the acrylamide content in roasted potato wedges, especially in the experiments performed after long-term storage, where the acrylamide content was reduced from 110-260 to 50-140 microg/kg. No correlation was found between precursor content and acrylamide content, and this finding emphasizes the need for further studies on factors affecting acrylamide formation, for example, the availability of precursors at the surface during cooking.     

Reducing Acrylamide in Fried Snack Products by Adding Amino Acids

ABSTRACT: The aims of this study were to develop commercial methods for reducing the acrylamide content in processed foods and apply them to commercial snacks. The formation of acrylamide in fried foods was found to depend on the composition of raw materials as well as the frying time and temperature. In potato chips, acrylamide was rapidly formed at over 160°C, with the amount proportional to the heating duration and temperature. Free amino acids were used to reduce acrylamide, with lysine, glycine, and cysteine having the greatest effects in the aqueous system. Lysine and glycine were effective at inhibiting the formation of acrylamide in wheat-flour snacks. In potato snacks, the addition of 0.5% glycine to pallets reduced acrylamide by more than 70%. Soaking potato slices in a 3% solution of either lysine or glycine reduced the formation of acrylamide by more than 80% in potato chips fried for 1.5 min at 185°C. These results indicate that the addition of certain amino acids by soaking the uncooked products in appropriate solutions is an effective way of reducing acrylamide in processed foods.     

QUALITY CHARACTERISTICS OF LOW-FAT FRANKFURTERS MANUFACTURED WITH POTATO STARCH, FINELY GROUND TOASTED BREAD AND RICE BRAN

Low-fat frankfurters (10% fat, 13% protein) were produced with 3.0% potato starch, finely ground toasted bread and rice bran or their combination. No differences (P > 0.05) were found in processing yield and purge accumulation among treatments of tested ingredients. Potato starch (3.0%) significantly increased the lightness, hardness and skin strength of low-fat frankfurters. Finely ground toasted bread had the highest scores for visual color, external redness, flavor intensity and overall acceptability and improved (P < 0.05) skin strength of frankfurters in comparison to potato starch. Low-fat frankfurters with 3.0% rice bran had the same (P>0.05) visual color scores, redness and textural properties as those produced with potato starch and toasted bread, but lower (P < 0.05) flavor intensity and overall acceptability and were judged as "just acceptable". Decreasing the rice bran from 3.0 to 1.5% and using it in combination with toasted bread (0.75%) and potato starch (0.75%) had an insignificant effect on the flavor intensity and overall acceptability of low-fat frankfurters.     

Effect of frozen storage duration and cooking on physical and oxidative changes in M. Gastrocnemius pars interna and M. Iliofiburalis of Rhea americana

This study was conducted to evaluate the effect of frozen storage time (30, 60, 90 or 180 days) and cooking (100 °C, 30 min) on the physical characteristics and oxidative stability of M. Gastrocnemius pars interna (GN) and M. Iliofiburalis (IF) of rhea americana. Physical parameters measured included thawing and cooking loss, colour parameters (L*a*b*), while oxidation was assessed by determining the TBA-RS, carbonyl and aromatic amino acid content. Prolonged frozen storage of rhea meat decreased lightness (L*), yellowness (b*), and increased the discoloration parameter hue angle and redness a*. During storage, muscle IF was more prone to lipid and myoglobin oxidation than muscle GN. Cooking loss declined with the increase of storage time and was higher in GN than in IF muscle. With cooking, TBA-RS, carbonyl content, and aromatic amino acids (phenylalanine, tyrosine, and tryptophan) were highly affected, but the extent of oxidation ranged according to muscle and duration of frozen storage.     

The measurement of hair colour

The colour of the hair of 65 subjects was measured using a Minolta Chromameter model CR200. Readings were taken by holding the unit against the back of the subject's head, and recorded using the L*a*b* system of colour co-ordinates.
All subjects had hair in which yellow and red (rather than blue or green) dominated. The lightness (L*) of all hair fell in the range 17–67, the redness (a*) in the range 0–6 and the yellowness (b*) 0–20. These limits can be seen as effectively outlining the range of colours which can be said to be natural.
The chromameter gave rapid and reproducible results on hair in situ and was easy to use. The method should be of use to those who wish to quantify the effects brought about by bleaching or dyeing formulations.     

Effects of various cellulose gums on the quality parameters of low-fat breakfast sausages

Composition, textural, viscoelastic, hydration, colour and sensory attributes of regular (26% fat) and low-fat (13%) pork breakfast sausages with and without cellulose gums (two types of carboxymethyl cellulose (CMC-I and -II) and microcrystalline cellulose (MCC-I and -II)) were investigated. The fat was replaced with water in low-fat products. In cooked low-fat sausages, the fat content decreased by 52-60%, and moisture content reduced by 61-65% of the initial values. The cooked high-fat products' composition showed an increase of about 6% fat and a decrease of 7% moisture due to cooking. MCC was more effective in retaining moisture compared to CMC. Product lightness was reduced due to both CMC and MCC. Gums have not affected fat content, water holding capacity, redness, yellowness, hardness, chewiness and gumminess. High-fat products were less elastic and easier to chew. Springiness was reduced by CMC-II and cohesiveness by other cellulose gums.     

Color changes and acrylamide formation in fried potato slices

The objective of this work was to study the kinetics of browning during deep-fat frying of blanched and unblanched potato chips by using the dynamic method and to find a relationship between browning development and acrylamide formation. Prior to frying, potato slices were blanched in hot water at 85 °C for 3.5 min. Unblanched slices were used as the control. Control and blanched potato slices (Panda variety, diameter: 37 mm, width: 2.2 mm) were fried at 120, 150 and 180 °C until reaching moisture contents of ∼1.8% (total basis) and their acrylamide content and final color were measured. Color changes were recorded at different sampling times during frying at the three mentioned temperatures using the chromatic redness parameter a¹. Experimental data of surface temperature, moisture content and color change in potato chips during frying were fit to empirical relationships, with correlation coefficients greater than 90%. A first-order rate equation was used to model the kinetics of color change. In all cases, the Arrhenius activation energy decreases alongside with decreasing chip moisture content. Blanching reduced acrylamide formation in potato chips in ∼64% (average value) in comparison with control chips at the three oil temperatures tested. For the two pre-treatments studied, average acrylamide content increased ∼58 times as the frying temperature increased from 120 to 180 °C. There was a linear correlation between acrylamide content of potato chips and their color represented by the redness component a¹ in the range of the temperatures studied.     

The effect of the method of drying on the colour of dehydrated products

Summary We tested the hypothesis that an optimum method of drying fruit could be designed. The effect of the method used for drying on colour of apple, banana, potato and carrot was investigated for five different methods of drying: conventional, vacuum, microwave, freeze and osmotic drying. Colour characteristics were studied by measuring lightness (L), redness (a) and yellowness (b) using a Hunter Lab chromatometer. The method used to dry the material was found to significantly affect the three colour parameters. The changes in redness (a) and yellowness (b) were found to follow a first order kinetic model. Air-, vacuum- and microwave-dried materials caused extensive browning in the fruits and vegetables, this was manifested by a significant drop of the L parameter and an increase of the a and b parameters. Osmotically pretreated samples did not brown as much as the untreated samples and the value for lightness (L) decreased only slightly while a and b increased slightly. Freeze drying seems to prevent colour changes, resulting in products with improved colour characteristics.     

Study of colour and acrylamide formation in coffee,wheat flour and potato chips during heating

The effects of heating on colour generation measured as CIE colour space parameters of L* a* b* and acrylamide formation were studied in various food matrices including green coffee, wheat flour and potato chips at different temperatures. Changes in both the acrylamide concentration and the redness parameter a* during heating at relatively higher temperatures followed a typical kinetic pattern in which an initial increase to an apparent maximum followed by a subsequent decrease was observed. The similarities between the changes in acrylamide and redness parameter a* during heating revealed that colour may be a reliable indicator of acrylamide levels in thermally processed foods. The overall results suggest that both acrylamide and redness parameter a* form as intermediate products during Maillard reaction. Since an apparent decrease was observed in its level during prolonged heating at certain temperatures, prediction of acrylamide level in foods during processing should be based on realistic reaction mechanism, instead of simple linear regression model.     

Influence of ultrasound pretreatments on diffusion coefficients,texture and colour of osmodehydrated sweet potato (Ipomea batatas)

The moisture and solute diffusivities, texture and colour of sweet potato pretreated in distilled water with ultrasound (UD), osmotic dehydration without ultrasound (OD) and osmotic dehydration with ultrasound (UOD) were investigated to determine the effects of ultrasound on osmodehydrated sweet potato. The moisture and solute diffusivities of all the pretreatments ranged from 2.89 to 4.95 × 10^?10 and 1.17 to 1.67 × 10^?10 m² s^?1, respectively. The moisture diffusivity of samples treated in UOD was significantly (P < 0.05) higher than that of OD and UD by 30.82% and 41.62%, respectively. Compared to the fresh sample, the firmness of samples treated in OD and UOD was reduced by 83.53% and 92.47%, respectively. UD increased the brightness (L*) and reduced the redness (a*) of sweet potato, while UOD enhanced the yellowness (b*) and chroma (C*) of sweet potato. The sweet potato samples treated in UOD had the highest total colour difference (ΔE).     

Acrylamide elution from roasted barley grains into mugicha and its formation during roasting

This paper investigated acrylamide elution from roasted barley grain into mugicha and its formation during roasting of the grain. Mugicha is an infusion of roasted barley grains. Highly water-soluble acrylamide was easily extracted to mugicha from milled roasted barley grains in teabags. On the other hand, the acrylamide concentration in mugicha prepared from loose grain increased with longer simmering and steeping times. During roasting in a drum roaster, the acrylamide concentration of the grain increased as the surface temperature rose, reaching a maximum at 180–240°C. Above this temperature, the acrylamide concentration decreased with continued roasting, exhibiting an inverted ‘U’-shaped curve. For most of the samples, the acrylamide concentration showed good correlation with the value of the colour space parameter L*. The dark-coloured roasted barley grains with lower L* values contained lower amounts of acrylamide as a result of deep roasting. The level of asparagine in barley grains was found to be a significant factor related to acrylamide formation in roasted barley products. The data are an important contribution to the mitigation of acrylamide intake from mugicha.     

不同有机酸雾化喷淋处理对鸡胴体表面减菌效果的影响

以某屠宰加工厂的鸡胴体为实验对象,研究食品中常见的乳酸、丙酸、酒石酸、柠檬酸、葡萄糖酸、山梨酸钾和焦磷酸钠（质量分数均为2%）对鸡胴体雾化喷淋处理后的减菌效果及复合有机酸雾化喷淋处理后对鸡胴体在贮藏期间品质的影响。结果表明：柠檬酸、丙酸和酒石酸对鸡胴体表面的菌落总数和乳酸菌、葡萄球菌属、假单胞菌属、热杀索丝菌、肠杆菌科的减菌效果较好;对柠檬酸、丙酸和酒石酸进行复合喷淋减菌效果研究,确定1%（质量分数,下同）柠檬酸、0.5%丙酸和0.5%酒石酸的复合喷淋减菌效果优于单一有机酸喷淋处理,且复合有机酸喷淋处理后对鸡胴体的红度、黄度和亮度值基本无影响;在11 d的贮藏期内,复合有机酸喷淋处理后鸡胴体的菌落总数、挥发性盐基氮和硫代巴比妥酸反应产物含量都明显降低。因此,复合有机酸雾化喷淋处理对鸡胴体具有明显的减菌效果,并可延长产品的货架期。     

腌制蒸煮猪肉切片冷藏期间色泽变化与氮的存在形式及氧化状态的关系

本研究以腌制蒸煮的猪肉切片为研究对象,通过对其冷藏期间的猪肉的色泽、理化指标、游离氨基酸、生物氨和一些氧化指标进行跟踪检测,利用主成分分析法阐明猪肉切片冷藏期间色泽变化与氮的存在形式及氧化状态的关系。结果表明,猪肉切片冷藏期间褪色显著(P<0.05),亮度(L*)、红度(a*)、黄度(b*)、色调(Hue)、色饱和度(C)和亚硝基血色原(NH)均发生了显著性变化(P<0.05)。生物胺中只有酪胺(TYR)、亚精胺(SPD)和精胺(SPM)发生显著性变化(P<0.05),游离氨基酸之和(∑FAA)在冷藏期间无显著性变化,非蛋白氮(NPN)、羰基(CARB)和共轭二烯值(DV)在冷藏期间发生显著性变化(P<0.05)。通过因子分析,可以看到,游离氨基酸之和除跟色调(Hue)正相关(r=0.829)以外,与其他色泽指标呈显著负相关(P<0.05)。生物胺中,除了色胺(TRY)与亮度(L*)呈显著负相关外,其他生物胺与色泽无显著相关(P<0.05)。     

响应面法优化低脂甘薯脆片加工工艺

以红心甘薯为原料,优化低脂甘薯片生产过程中漂烫、热风干燥、油炸等关键工艺参数,以产品含油率和色差(L*值和b*值)为评价指标,并通过响应面优化确定最优的低脂甘薯片生产工艺.结果表明,较优漂烫工艺条件为:漂烫温度70℃,漂烫时间7 min;较优的热风干燥工艺条件为:热风干燥温度70℃,热风干燥时间40 min;最优油炸工...     

Effective quality control of incoming potatoes as an acrylamide mitigation strategy for the French fries industry

The correlation between sugar levels in raw material (potatoes), brown colouring and formation of acrylamide in French fries was investigated. The objective was to identify incoming potatoes (raw material) with a high potential for acrylamide formation. Ten different potato varieties commonly used in the Western European French fries industry were stored at 8°C and samples were taken throughout the storage time. The current quality control used in the French fries industry for incoming potatoes is poorly correlated with acrylamide in the final product (r = 0.74). Changing the quality control parameter from colour to reducing sugars in raw material did not improve the correlation (r = 0.72). The best correlation was obtained with the Agtron colour measurement after blanching and a two-stage frying (r = ?0.88). It was concluded that alternative entrance control measurements could provide better mitigation of the acrylamide issue in French fries from the start of production. These alternatives, however, are less cost-effective and more difficult to implement.