Survival of a Salmonella typhimurium experimental contaminant during cooking of beef roasts.

Twenty-one raw boneless beef roasts were experimentally injected with 2 X 10(7) cells of a nalidixic acid-resistant strain of Salmonella typhimurium per roast. Contaminated roasts were cooked to center internal temperatures of 137.0 to 147.5 degrees F (58.3 to 64.1 degrees C) in a gas-fired pilot plant food-processing oven. Viable experimental contaminants were recovered from two core samples of the 21 roasts (one cooked to 137.0 degrees F [58.3 degrees C] and one cooked to 141.5 degrees F [ca 60.8 degrees C]). All of 17 cooking net samples taken from the contaminant injection side of roasts were salmonella positive, whereas 7 of 9 net samples from the side opposite injection were positive and all of 11 net samples from the bottom of roasts were positive. The implications of these results are discussed in relation to salmonella contamination of precooked beef roasts.     

Survival of a Salmonella typhimurium experimental contaminant during cooking of beef roasts.

Twenty-one raw boneless beef roasts were experimentally injected with 2 X 10(7) cells of a nalidixic acid-resistant strain of Salmonella typhimurium per roast. Contaminated roasts were cooked to center internal temperatures of 137.0 to 147.5 degrees F (58.3 to 64.1 degrees C) in a gas-fired pilot plant food-processing oven. Viable experimental contaminants were recovered from two core samples of the 21 roasts (one cooked to 137.0 degrees F [58.3 degrees C] and one cooked to 141.5 degrees F [ca 60.8 degrees C]). All of 17 cooking net samples taken from the contaminant injection side of roasts were salmonella positive, whereas 7 of 9 net samples from the side opposite injection were positive and all of 11 net samples from the bottom of roasts were positive. The implications of these results are discussed in relation to salmonella contamination of precooked beef roasts.     

EFFECT OF MEAT APPEARANCE ON SOUTH KOREAN CONSUMERS' CHOICE OF PORK CHOPS DETERMINED BY IMAGE METHODOLOGY

The effect of appearance characteristics of fresh pork on Korean consumers' preferences was assessed using images of pork chops. Consumers (1015) in six provinces selected their preferred chop from 16 images modified systematically to give two levels each of fat cover, color, marbling and drip. Meat color was the most important characteristic; similar numbers of consumers chose the dark and light red meat colored pork. Almost two‐thirds of the consumers chose consistently the option without drip. A strong characteristic was that almost half of the Korean consumers chose the marbled pork, although fat cover was not an important selection criterion. Similar preferences were observed on a regional basis, except for color, which varied according to region. More female, particularly the married ones, than male consumers preferred the light red, no drip and marbled options.     

Changes in color and texture of wheat noodles during chilled storage

Wheat noodles cooked for different periods of time were stored at 5 °C, and color changes in their cross sections were quantitatively assessed by digital image analysis. The color of noodles with flattened moisture distributions whitened greatly during the early stages of chilled storage due to the retrogradation of starch, with the color change showing a significant correlation with the changes in noodle fragility. Color changes were also measured for wheat noodles and noodles containing modified starch with internal moisture distributions, and local changes within the noodles were kinetically analyzed. The addition of modified starch significantly reduced the color change in the noodle interior, where the moisture content was relatively low. Scanning calorimetric measurements indicated differences in the gelatinized state of modified starch and original wheat starch at low moisture contents, which affected the rate of color change in the interior of noodles containing modified starch.     

SENSORY EVALUATION OF INDIAN-STYLE MARINATED CHICKEN BY MALAYSIAN AND EUROPEAN NAÏVE ASSESSORS

This study was carried out to determine the sensory acceptability of chicken breast fillets marinated with 13 different commercially available Indian-style marinades. Thirty-four naïve assessors (untrained panelists), 20 Malaysian and 14 European, were selected to assess the following sensory attributes: color, color uniformity, Tikka-Masala aroma, Tikka-Masala flavor, herblike flavor, hotness, authenticity, juiciness and overall acceptability. The color of the cooked samples and the pH, moisture and fat content of the marinades were analyzed instrumentally. Marinades were applied to the chicken fillets, which were then dry cooked at 170C for 15 min to an internal temperature of 73C. Sensory evaluation showed significant differences ( P <  0.05) in color uniformity, hotness and juiciness of the cooked marinated chicken perceived between groups. Samples marinated with marinades L and I received the highest score from the Malaysian panelists in terms of overall acceptability, whereas marinades A and F were chosen by the European group.

PRACTICAL APPLICATIONS

The findings from this research will benefit manufacturers of marinade and marinated chicken products in developing or optimizing their products for the local and international markets. The optimal characteristics of an ideal marinade were identified for each assessor group. These results are also of interest to individuals undertaking cross-cultural consumer studies, even though the results presented here used naïve assessors.     

Genetic relationships between composition of pork bellies and performance, carcase and meat quality traits

Belly traits including predicted fat percentage of the belly (FATPC), combined area of the rib bone and muscle (RBMA), intermuscular fat area (IMFA) and subcutaneous fat area (SFA) were recorded on 2403 pigs along with carcase fat depth at the P2 site (P2). Belly traits were derived from image analysis of the anterior side of pork bellies. Further data available for pigs with belly data and their contemporaries included lifetime growth rate, ultrasound backfat and loin muscle depth (35 406 records), along with meat quality traits (3935 records). There were 4586 feed intake records and 18 398 juvenile insulin-like growth factor-I (IGF-I) records available, which included the majority of pigs with belly data. Genetic parameters were estimated based on an animal model using Residual Maximum Likelihood procedures. Heritability estimates for belly traits ranged from 0.23 to 0.34 (±0.05 to 0.06) while the common litter effect varied from 0.04 to 0.07 (±0.03). Genetic correlations between FATPC, individual belly fat measurements and carcase P2 fat depth differed significantly from unity, ranging from 0.71 to 0.85 (±0.05 to 0.08). Genetic correlations between IMFA and subcutaneous fat measurements varied from 0.47 to 0.63 (±0.08 to 0.13). Genetic correlations between belly and performance traits show that selection for reduced juvenile-IGF-I, reduced feed intake and reduced backfat along with increased loin muscle depth will reduce overall fat levels in the belly. Only loin muscle depth had a significant genetic correlation with RBMA (0.32 ± 0.10), thereby assisting selection for improved lean meat content of the belly. Ultimately, genetic improvement of belly muscles requires specific measurements of lean meat content of the belly. For this to be effective, measurements are required that can be routinely recorded on the slaughter line, or preferably on the live animal.     

Effects of drying conditions on moisture distribution in rehydrated spaghetti

Moisture distributions in spaghettis prepared at a maximum temperature of 50, 70, or 85?°C, designated as LT-, HT-, or VHT-spaghetti, respectively, and cooked to the average moisture content of 1.71?±?0.01?kg-H₂O/kg-d.m., were measured. The moisture contents near the surface and at the center of the LT-spaghetti were lower and higher, respectively, than those of HT- and VHT-spaghetti.     

Physical,chemical and organoleptic properties of ram lamb carcasses from four fat-tailed genotypes

Physical, chemical and organoleptic characteristics of 20 ram lambs representing four fat-tailed genotypes Awassi, Red Karaman, Tushin and Awassi×Tushin were compared. After slaughter, carcasses were chilled at 5°C for 24 h, graded and evaluated. Then, the carcasses were dissected into wholesale cuts and longissimus dorsi (LD) and semimembranosus (SM) muscles were excised. The muscles were subjected to moisture, protein, fat and ash analyses and they were cooked to evaluate palatability. Cold carcass weight of RK and A×T lambs were heavier (P<0.01) than those of A and T lambs. A×T crossbreds had higher (P<0.05) cold dressing percentage and larger LD area than T lambs. However, the influence of genotype on the proportion of boneless retail cuts and marbling were not significant. Most of the proportions of wholesale cuts except for sirloin and flank were not affected by the genotype. The sensory panel found the meat from all genotypes acceptable (tenderness, juiciness, flavor and acceptability). Chemical composition of meat from the different genotype was not significantly different. The study reveals generally insignificant differences in chemical, physical and organoleptic properties between fat-tailed lambs with different genetic backgrounds.     

Rhodnius prolixus LIPOPHORIN: LIPID COMPOSITION AND EFFECT OF HIGH TEMPERATURE ON PHYSIOLOGICAL ROLE

Lipophorin is a major lipoprotein that transports lipids in insects. In Rhodnius prolixus, it transports lipids from midgut and fat body to the oocytes. Analysis by thin‐layer chromatography and densitometry identified the major lipid classes present in the lipoprotein as diacylglycerol, hydrocarbons, cholesterol, and phospholipids (PLs), mainly phosphatidylethanolamine and phosphatidylcholine. The effect of preincubation at elevated temperatures on lipophorin capacity to deliver or receive lipids was studied. Transfer of PLs to the ovaries was only inhibited after preincubation of lipophorin at temperatures higher than 55°C. When it was pretreated at 75°C, maximal inhibition of phospholipid transfer was observed after 3‐min heating and no difference was observed after longer times, up to 60 min. The same activity was also obtained when lipophorin was heated for 20 min at 75°C at protein concentrations from 0.2 to 10 mg/ml. After preincubation at 55°C, the same rate of lipophorin loading with PLs at the fat body was still present, and 30% of the activity was observed at 75°C. The effect of temperature on lipophorin was also analyzed by turbidity and intrinsic fluorescence determinations. Turbidity of a lipophorin solution started to increase after preincubations at temperatures higher than 65°C. Emission fluorescence spectra were obtained for lipophorin, and the spectral area decreased after preincubations at 85°C or above. These data indicated no difference in the spectral center of mass at any tested temperature. Altogether, these results demonstrate that lipophorin from R. prolixus is very resistant to high temperatures.     

Effects of carcass maturity on meat quality characteristics of beef semitendinosus muscle for chinese native yellow steers

This work was designed to study the effects of carcass maturity on meat quality characteristics and intramuscular connective tissue of beef semitendinosus muscle from Chinese native Yellow steers. Chemical determinations, histological and mechanical measurements were performed on the raw and cooked meat at 4 days post mortem. In raw meat, intramuscular fat, collagen solubility, mechanical strength and transition temperature of intramuscular connective tissue increased (P < 0.05) with carcass maturity before body maturation, whilst moisture, total collagen, fibre diameter decreased after body maturation. Warner-Bratzlar shear force (WBSF) of cooked meat increased with maturity before body maturation due to the muscle atrophy, and thus the decline of moisture content and the increase of cooking losses. After body maturation, the increase of WBSF was neutralised by the increase of intramuscular fat, the decrease of total collagen and the elongation of sarcomere length.     

MyoG基因的遗传效应分析

实验采用PCR-RFLP技术分析了不同品种猪MyoG基因3′端MspⅠ位点的多态性,应用单标记回归模型分析了不同基因型与相关性状间的关联性及不同等位基因的遗传效应。结果表明：N等位基因能极显著地增加胴体瘦肉率和眼肌面积,降低皮脂含量（P<0.01）,改善胴体产肉量和提高胴体品质;同时,不同基因型对肉质性状的遗传影响作用较大,表现为N等位基因能极显著地降低猪肉品质,使pH值、肉色和肌内脂肪含量降低,并使肌肉的系水力变差（P<0.01）。N等位基因对增加胴体瘦肉率的加性效应值和显性效应值分别为3.929%和-0.602%;对增加眼肌面积的加性效应值和显性效应值分别为2.0985 cm2和-0.5775 cm2;对皮脂率的加性效应值为-3.0245%,显性效应值为-0.4045%。N等位基因对pH1的加性效应值和显性效应值分别为-0.167和0.034;对贮藏损失的加性效应值和显性效应值分别为0.558和-0.347;对肌内脂肪含量的加性效应值和显性效应值分别为-0.963和-0.217。但MyoG基因3′端MspⅠ位点的突变对FOM肉脂仪测定的胴体等级性状的影响不显著（P>0.05）。     

Comparison of meat and carcass quality in organically reared and conventionally reared pasture-fed lambs

The 'Organic' product label guarantees a production process that avoids the use of synthetic fertilisers, pesticides and hormones and minimises recourse to pharmaceuticals or veterinary drugs; however, the product's quality remains an issue that needs to be addressed in response to consumer demand. Consequently, this study was conducted to compare the sensory and nutritional qualities of meat and carcasses from pasture-fed lambs reared organically (O) or conventionally (C). Mean lamb growth profile was kept similar between the two treatments to avoid confounding effects with lamb age or weight at slaughter. The experiment was conducted over 3 years (2005 to 2007) with 12 O and 12 C lambs each year. The O and C treatments differed in the level of on-pasture mineral N fertilisation inducing a higher proportion of white clover in the organic pasture than the conventional pasture. Lambs were slaughtered when they attained a fat class of 2 to 3, and carcass and meat quality were evaluated. Lambs were slaughtered at an average weight and age of 35.3 kg and 156 days in the O treatment, respectively, and 35.2 kg and 155 days in the C treatment, respectively. Sensory evaluation indicated that loin chops from the O treatment had a higher level of abnormal fat odour compared with the C treatment. Carcasses from the O treatment had a softer subcutaneous fat one among 3 years (2007) compared to the C treatment. These results are probably due to a higher proportion of white clover in the diet. Organically reared lambs did offer the slight advantage of muscle fatty acid containing a higher level of stearic acid, which may have positive effects in the prevention of cardiovascular disease in humans. This may be the result of a higher rumen bio-hydrogenation of C18:3n-3 due to differences in the botanical composition between the O and the C pasture. Production system had no effect on the colour characteristics of the meat and subcutaneous fat, except lightness of subcutaneous dorsal fat, which was slightly higher in the O lambs. There were no differences between O and C lambs in terms of colour stability and lipid oxidation of the meat during the 6-day refrigerated storage under gas-permeable film.     

DEVELOPMENT OF A LEXICON FOR BEEF FLAVOR IN INTACT MUSCLE

ABSTRACT

A lexicon describing the flavor characteristics of beef across different cuts, grades, and cooking temperatures and methods was developed. Four major cuts of the United States Department of Agriculture (USDA) quality grade beef were cooked to five endpoint temperatures using braising, broiling (oven broiling and electric charbroiling), roasting and grilling (indoor and outdoor grilling). Six highly trained panelists identified and defined a total of 38 aroma and flavor characteristics in 176 beef samples. Beef identity, brown/roasted, bloody/serumy, metallic, fat‐like, overall sweet, sour aromatics and five tastes were present in practically all samples. Other attributes were present only in certain samples, depending on either the sample group or the cooking method/endpoint temperature combination used. This lexicon potentially offers the beef industry a standard tool to identify and quantify flavor attributes as impacted by temperature, cooking method, aging process, storage time, diet regime, packaging, USDA quality grades, etc.

PRACTICAL APPLICATIONS

Until now, the beef industry's main focus has been to assess beef tenderness and juiciness, with an emphasis on ways to improve beef texture. Meat companies and academic institutions have been using the 1995 American Meat Science Association guidelines to assess the flavor of beef, which are not comprehensive. Recent work has focused on flavor, and the industry needs a standardized flavor lexicon that can be used for many projects. It is important for the industry to be able to systematically identify and quantify flavor attributes that drive consumer acceptance.     

天山北坡积雪消融对不同冻融阶段土壤温湿度的影响

积雪作为一种特殊的覆被,直接影响着土壤温度、土壤水分分布及其冻结深度、冻结速率等,影响当地的生态水文过程。利用2017年11月1日至2018年3月31日天山北坡伊犁阿热都拜流域的土壤含水率资料,划分土壤不同冻融阶段,结合积雪不同阶段,进而分析积雪消融对季节性冻土温湿度的影响。结果表明:在整个土壤冻融期间,土壤温湿度的变化取决于积雪深度、大气温度和雪面温度的高低,且与其稳定性有关。土壤冻结阶段,土壤温湿度持续下降,表层土壤温湿度受气温影响较大,且波动明显,而深层土壤的温湿度变化平缓;土壤完全冻结时,有稳定积雪覆盖,由于积雪的高反射性、低导热性,影响着地气之间的热量传递,因此土壤的温湿度变化较为平稳,积雪有一定的保温作用;冻土消融阶段,气温回升,积雪消融,地表出露,各层土壤温度随气温变化而变化,且越靠近地表,土壤温度越高,变幅越大,与冻结期完全相反。由于融雪水的下渗,土壤湿度快速增加。进一步分析积雪与土壤温湿度的相关性得出,积雪对土壤温湿度的影响分不同时期,对土壤温度的影响主要在积雪覆盖时,对土壤湿度的影响主要是在积雪消融时期,这对于研究该地生态水文循环及后续融雪性洪水的模拟与预报具有一定的参考价值。     

COMPARING TRANS-FAT AND TRANS-FAT-FREE DOUGHNUT SHORTENINGS BASED ON SENSORY EVALUATION AND OIL DEGRADATION

This is an initiative study on the use of trans -fat-free products in the bakery industry. A standardized doughnut product was cooked in three doughnut shortenings, one containing trans fat and two that were trans fat-free. Six hundred forty-one panelists, students, faculty and staff of a large northeastern university rated each of the three doughnuts on a variety of categories, including texture, moisture content and overall liking. Results showed that there were no significant differences between doughnuts cooked in the three shortenings – this was true for all attributes tested.
The results from this study have many significant implications for the foodservice industry, as they work to cut down or eliminate the use of trans fats in their establishments because of the significant health risks they have been proven to cause.

PRACTICAL APPLICATIONS

This study demonstrates the variances on texture, taste, appearance and overall liking characteristics of doughnuts fried in different doughnut shortenings. The nutritional breakdown of the doughnuts and the shortenings are also addressed. In the case of shortenings, the ideal type of fat is a mixture of canola, soybean and hydrogenated cottonseed. This shortening mixture, which is trans fat-free, produced the most preferred doughnut.     

High pressure processing for food safety

Food preservation using high pressure is a promising technique in food industry as it offers numerous opportunities for developing new foods with extended shelf-life, high nutritional value and excellent organoleptic characteristics. High pressure is an alternative to thermal processing. The resistance of microorganisms to pressure varies considerably depending on the pressure range applied, temperature and treatment duration, and type of microorganism. Generally, Gram-positive bacteria are more resistant to pressure than Gram-negative bacteria, moulds and yeasts; the most resistant are bacterial spores. The nature of the food is also important, as it may contain substances which protect the microorganism from high pressure. This article presents results of our studies involving the effect of high pressure on survival of some pathogenic bacteria -- Listeria monocytogenes, Aeromonas hydrophila and Enterococcus hirae -- in artificially contaminated cooked ham, ripening hard cheese and fruit juices. The results indicate that in samples of investigated foods the number of these microorganisms decreased proportionally to the pressure used and the duration of treatment, and the effect of these two factors was statistically significant (level of probability, P 相似文献   

四川自贡大山铺中侏罗世蜀龙和峨眉龙长骨骨组织结构的初步研究

通过对四川自贡大山铺恐龙动物群中两种主要蜥脚类恐龙—李氏蜀龙和天府峨眉龙肱骨和尺骨的骨组织结构观察,并与我国晚白垩世的几种恐龙长骨进行对比,结果发现:1)恐龙的长骨都具有快速的后生生长速率;2)恐龙的生长方式属于非限定生长,即在成年后并不停止生长;3)不同类型的恐龙到了成年以后,其骨沉积速率可能有较大差异;4)不同类型的恐龙在长骨的生长改建过程中,骨组织内部的重吸收作用有较大差异;5)生长轮结构在不同部位的骨骼中或在骨骼的生长发育过程中可能也有较大差异。     

荞麦籽粒结构的观察与分析

从荞麦籽粒的和分析中可以看出,荞麦的果皮和种皮容易分开,种子中心巨大的“Ｓ”形胚芽、胚根以及糊粉层虹适量科贮藏蛋白质存在的主要场所。在“Ｓ”形胚芽和胚根两侧是荞麦的两片叶子,由淀粉贮藏细胞组成。该细胞呈长方多棱体,细胞壁极薄且透明,人淀粉粒呈多面球形,大小均匀整齐,淀粉粒间结合紧密、严实,具有一定的几何构形。在淀粉粒间未发现基质蛋白质。     

植被覆盖度和归一化湿度指数对热力景观格局的影响——以广州为例

利用LANDSAT-5 TM影像提取地表温度、植被覆盖度和归一化湿度指数(NDMI)等信息,结合景观生态学方法探讨广州市不同区域城市植被和NDMI对地表温度的调节作用.结果表明:植被覆盖度、NDMI和地表温度两两之间有较强的线性相关性,但不同区域植被覆盖度、NDMI与地表温度的相关程度存在明显差异;提高相同植被覆盖度时,中心城区的降温效果最好,其次是处于中心城区北缘的近郊区;不同区域森林公园对周围热环境的影响程度不同,960～1080 m缓冲区内平均温度与公园内部平均温度之差分别为4.69℃(白云山)、1.27℃(马仔山)和0.41℃(流溪河);高植被覆盖度可增加热力景观多样性和不同景观之间的结合度,促进低温斑块内部与其他斑块如高温斑块间的能量交换,起到控制热岛效应的效果;增加环境湿度与提高植被覆盖度对热力景观格局所形成的作用相当.