FA100型多功能气流塔的开发和应用

为了解决清梳联流程中单轴流开棉机由于工艺风量、风压配置不合理,出现易堵车而造成停产的问题,介绍了专利产品——FA100型多功能气流塔开发的背景及其结构、特点。该设备通过两次释压,解决从抓棉到开棉、混棉间的气流不平衡问题,通过试验和实际使用,指出多功能气流塔能有效解决单轴流的堵车,保证清梳联的稳定运行;在除尘、重物分离和去铁杂等方面也有着较为理想的效果;能解决原各辅机在输棉管路中分散接入的缺点,简化了清梳联流程;能提高生条、成纱的质量。说明多功能气流塔在生产实际中有着较高的实用价值。     

Matrix effects on flavour volatiles release in dark chocolates varying in particle size distribution and fat content using GC–mass spectrometry and GC–olfactometry

Influences of matrix particle size distribution (PSD) (18, 25, 35 and 50 μm) and fat content (25%, 30% and 35%) on flavour release of dark chocolate volatiles were quantified by static headspace gas chromatography using GC–MS. Sixty-eight (68) flavour compounds were identified, comprising alcohols, aldehydes, esters, ketones, furans, pyrans, pyrazines, pyridines, pyroles, phenols, pyrones and thiozoles. From GC–olfactometry, 2-methylpropanal, 2-methylbutanal and 3-methylbutanal had chocolate notes. With cocoa/roasted/nutty notes were trimethyl-, tetramethyl-, 2,3-dimethyl-, 2,5-dimethyl-, 3(or 2),5-dimethyl-2(or 3)-ethyl- and 3,5(or 6)-diethyl-2-methylpyrazine and furfuralpyrrole. Compounds with fruity/floral notes included 3,7-dimethyl-1,6-octadien-3-ol and 5-ethenyltetrahydro-R,R,5-trimethyl-cis-2-furanmethanol. Caramel-like, sweet and honey notes were conferred by 2-phenylethanol, phenylacetaldehyde, 2-phenylethylacetate, 2,3,5-trimethyl-6-ethylpyrazine, 2-carboxaldehyde-1H-pyrrole, furancarboxaldehyde, furfuryl alcohol and 2,5-dimethyl-4-hydroxy-3(2H)furanone. There were direct relationships of fat content with 3-methylbutanal and branched pyrazines but inverse ones with 2-phenylethanol, furfuryl alcohol, methylpyrazine, phenylacetaldehyde, 2, 3, 5-trimethyl-6-ethylpyrazine and 2-carboxaldehyde-1-H-pyrrole. Particle size influenced higher alcohol, aldehyde, ester, ketone and pyrazine concentrations at all fat contents. A multivariate product space suggested flavour effects of the interacting factors.     

Characterising the release of flavour compounds from chewing gum through HS-SPME analysis and mathematical modelling

The headspace solid-phase microextraction (HS-SPME) technique combined with GC–MS was evaluated to study 33 selected flavour compounds released from chewing gum. The operating conditions of SPME were optimised, including different fibres (PDMS, DVB/CAR/PDMS, PA and PDMS/DVB), sample size, extraction time and temperature. The results indicated that while HS-SPME was a rapid and valuable technique, poor reproducibility occurred under all conditions. It was found that this deficiency could be alleviated by utilising mathematical modelling techniques, an approach which had not been previously used in the analysis of flavour compounds in chewing gum by HS-SPME. Compared to the instrumental analysis data themselves, the models provided more insights to the release behaviour of flavour compounds from chewing gum and the more reproducible kinetic rate constants might be used for comparing the release of different compounds or the same compound under different conditions.     

Effectiveness of a polyamide film releasing lactic acid on the growth of E. coli O157:H7, Enterobacteriaceae and Total Aerobic Count on vacuum-packed beef

The suitability of a polyamide 6 monolayer film containing lactic acid for use as an antimicrobial package for fresh beef cuts was studied. The release of lactic acid in an aqueous environment was immediate (within 1 h) and was from approx. 55 μg lactic acid/cm² film at 0–8 °C to approx. 67 μg lactic acid/cm² film at 12–20 °C. Beef was contaminated with an Escherichia coli O157:H7 isolate with known minimum inhibitory concentration against lactic acid (0.09% v/v), then wrapped with the lactic-acid polyamide film and vacuum packaged. During storage at 12 °C, the numbers of E. coli were 1 log unit lower than that of a control (untreated polyamide film) and decreased by an additional 1 log during storage for 14 days.     

毛皮中甲醛释放影响因素的研究

采用1m3环境舱模拟真实生活环境,通过改变温度、相对湿度、换气速率、承载率及释放部位等因素,考察对甲醛释放的影响。结果表明：（1）温度、相对湿度的增加会促进毛皮中的甲醛释放,且温度的影响更为明显。当温度从18℃增加到35℃．甲醛的最大释放量增加了102．51％。相对湿度从40％增加到60％．甲醛的最大释放量仅增加了15．52％。（2）随承载率的增加,释放源增多,甲醛释放量随之增加。通风换气,可以有效降低甲醛平衡浓度,改善室内环境质量。（3）毛皮的两面均为甲醛释放部位,肉面的甲醛释放量要略低于毛面。实际使用过程中,对毛皮的释放部位做适当封闭处理（加内衬、涂饰等）可以有效降低甲醛释放。     

大豆蛋白/壳聚糖复合膜的控释特性的研究

采用共混法形成壳聚糖(CS)-大豆蛋白(SPI)复合膜,并将茶碱包埋于其中制备茶碱的定位控释载体。结合红外分析和扫描电镜技术研究复合膜的释放特性和表面形态,其结果表明复合膜中大豆蛋白和壳聚糖之间存在交联作用;这种复合膜在胃肠液均呈溶胀状态,在模拟胃液中溶胀度较低,且在模拟肠液中降解速率较快。复合膜在模拟胃液中的释药速率相对模拟肠液要快,而且随着蛋白含量的增加,复合膜的溶胀度和释放率都随之降低,所有的复合膜对于茶碱的保护能保持至少7 h,因此壳聚糖-大豆蛋白复合膜可以用作控缓载体。     

E1级刨花板制备工艺的研究

研究讨论了热压温度、热压时间、板坯含水率、固化剂种类及用量等刨花板生产工艺参数对刨花板中游离甲醛含量的影响,从而对刨花板的生产工艺进行优化,得出了最佳工艺参数,并在工厂的批量生产中得到了验证。     

Supplementation of progesterone via controlled internal drug release inserts during ovulation synchronization protocols in lactating dairy cows

Our objective was to determine the effect of exogenous progesterone (P4) during a timed artificial insemination (TAI) protocol on pregnancies per AI (P/AI) in dairy cows not previously detected in estrus. Lactating cows (n = 3,248) from 7 commercial dairy herds were submitted to a presynchronization protocol (2 injections of PGF_2α 14 d apart; Presynch), and cows in estrus after the second PGF_2α received AI (EDAI; n = 1,583). Cows not inseminated by 12 to 14 d after the second PGF_2α injection were submitted to a TAI protocol (GnRH on d 0, PGF_2α on d 7, and GnRH + TAI 72 h after PGF_2α). At onset of the TAI protocol, cows were balanced by parity and days in milk and assigned randomly to receive no exogenous P4 (control, n = 803) or a controlled internal drug release (CIDR) insert containing 1.38 g of P4 from d 0 to 7 (CIDR, n = 862). Blood samples were collected at the second PGF_2α injection of the Presynch and on the day of the first GnRH injection of the TAI protocol for P4 determination. When P4 in both samples was <1 ng/mL, cows were classified as anovular, whereas cows having at least 1 sample ≥1 ng/mL were classified as cyclic. Concentration of P4 at 11 to 14 d after AI was determined in a subgroup of cows (n = 453) from 2 herds. Pregnancy was diagnosed at 40 ± 5 and 65 ± 5 d after AI. Proportion of cows inseminated on estrus after the second PGF_2α injection of the Presynch protocol differed among herds (range = 26.7 to 59.8%). Overall P/AI for EDAI cows at 40 ± 5 and 65 ± 5 d were 36.2 and 33.7%, respectively, and pregnancy loss was 8.8%. Proportion of cyclic cows at the onset of the TAI protocol differed among herds (range from 66.5 to 86.3%), but did not differ between treatments (control = 72.4%, CIDR = 74.1%). Treatment affected P/AI at 40 ± 5 (control = 33.3%, CIDR = 38.1%) and 65 ± 5 (control = 30.0%, CIDR = 35.1%) d after AI but did not affect pregnancy loss (8.6%). Cyclic cows had greater P/AI at 40 ± 5 (38.2 vs. 29.3%) and 65 ± 5 d (35.1 vs. 26.1%) after AI, but cyclic status had no effect on pregnancy loss. Treatment affected P4 concentration after AI, with more CIDR cows having P4 ≥1 ng/mL (94.4 vs. 86.9%) and P4 ≥3.2 ng/mL (81.8 vs. 68.0%) at 11 to 14 d after AI compared with control cows. Treatment of cows not previously detected in estrus with a CIDR insert during a TAI protocol increased proportion of cows with functional CL after AI and P/AI.     

Polymorphism in the bovine growth hormone gene affects endocrine release in dairy calves

The objective was to test whether calves with the Leu/Leu genotype release more growth hormone (GH) than calves with Leu/Val and Val/Val genotypes. Danish Holstein (n = 286), Danish Red (n = 68), and Danish Jersey (n = 61) calves were genotyped for the Leu/Val polymorphism in the GH gene and assessed for GH release following inducement by the growth hormone releasing hormone (GHRH). Three GH traits were assessed for each calf: BASELINE, PEAK, and RATE. BASELINE and PEAK are the mean concentration of GH in blood sampled before and after GHRH inducement. RATE is the disappearance rate of GH in blood sampled after GHRH inducement. Danish Jersey calves with Leu/Leu genotype had a higher PEAK and RATE than calves with the Val/Val genotype, whereas the Leu/Val genotype had an intermediate response. The contribution of the Leu/Val polymorphism to the total genetic variation of the BASELINE, PEAK, and RATE traits was 5, 30, and 27%, respectively. By contrast, the amount of GH released by the Danish Holstein and Danish Red calves was not influenced by their GH genotype. Further studies involving calves with all three genotypes are required to further elucidate whether this polymorphism has a functional role or whether it works through a linked-gene effect specific to certain cattle breeds.     

DEVELOPMENTS AND CHALLENGES IN FLAVOR PERCEPTION AND MEASUREMENT—A REVIEW

Flavor perception and measurement play important roles in the development of food products. In an increasingly commercial environment, the food industry must strive to minimize adverse consumer reactions. This article gives an extensive overview on the various methods used for flavor measurement. Principles of flavor release and perception are discussed and applications to quality assessment are demonstrated.