Application of extra sulfur to high-sulfur soils does not increase pungency and related compounds in shortday onions

Sulfur (S) nutrition has a strong influence on onion pungency, and the production of sweet onions in the high-sulfur soil of Texas is a challenge to growers. This study was performed to determine the effects of S applications to fields already having sufficient levels of soil S on pungency and related compounds in four shortday onion cultivars. The onion cultivars ‘Cougar’, ‘Legend’, ‘Texas Early White’, and ‘Texas Grano 1015Y’ were grown in three commercial fields at Edinburg, Mercedes, and Weslaco of the Rio Grande Valley of South Texas with applications of sulfur at 0, 13, and 26 kg S/ha. Pyruvic acid, bulb weight, extractable S in soil and total S in bulb, soluble solids content (SSC), flavor precursor compounds [also called S-alk(en)yl-l-cysteine-sulfoxides (ACSOs)], and total sugars were measured. The pyruvic acid level of onions was not increased by the S applications and showed no significant correlation with soil S levels in any of the cultivars at locations having 30 or 235 ppm S. The SSC, total S in bulbs, total sugars, and total ACSO content also showed no correlation with the S applications and soil S levels. Onion pungency and content of flavor precursor compounds were significantly influenced by cultivar and cultivar × location interaction. We conclude that onion pungency is not increased by application of extra S fertilizer to commercial fields already containing sufficient levels of soil sulfur.     

日粮核苷酸对机体炎症抗炎症平衡体系的影响

为探讨日粮核苷酸对小鼠炎症／抗炎症平衡体系的作用，用CpG DNA和脂多糖（LPS）刺激小鼠构建炎症反应模型，观察分别饲喂无核苷酸（NF）日粮和核苷酸（NT）日粮小鼠的炎性细胞因子IL-1、IFN-λ，、抗炎性细胞因子IL-10水平和小肠髓过氧化物酶（MPO）活性变化。结果显示，在刺激后第4h时，NT组小鼠的IL-1（P〈0．05）、IFN-λ，（P〈0．01）和小肠MPO（P〈0．01）明显低于NF组，IL-10（P〉0．05）高于NF组；刺激后第18h时，NT与NF组的IL-1（P〈0．01）、IFN-λ，（P〈0．01）、IL-10（P〉0．05）和MPO（P〈0．01）均较刺激后第4h有所降低，NT组的IL-1（P〉0．05）、IFN-λ，（P〈0．05）和小肠MPO（P〈0．05）仍低于NF组，IL-10（P〉0．05）仍高于NF组。表明，日粮核苷酸对CpG DNA或LPS所诱导的炎症反应有明显的抑制作用，有助于维持机体炎症／抗炎症平衡，保护机体免受炎症损伤。     

外源性环核苷酸对AA肉鸡脂肪和蛋白质代谢的影响

选用初生健康AA肉鸡 2 4 0只 ,随机分为 2组 ,每组 12 0只 ,每组内设 3个重复 :I组为试验组 ,每隔 4d皮下注射标准环核苷酸组合剂 ,剂量为每只鸡 0 1mL ;Ⅱ组为对照组 ,注射等量的生理盐水 ,共计 4 9d。研究结果表明 ,试验组鸡肝脏组织中总RNA、mRNA分别比对照组提高2 9 84 %和 2 6 0 3%。经单因子方差分析 ,组间均存在着显著差异 (P <0 0 1) ,血浆中cAMP和cGMP的浓度显著高于对照组 (P <0 0 1) ;血清中生长激素浓度升高 37 70 % ,球蛋白浓度提高了 34 0 9% ,甘油三酯浓度显著高于对照组 (P <0 0 1) ,尤其GOT、GPT等酶活性均有显著提高 (P <0 0 1)。     

Seasonal variations of free amino acids and nucleotide-related compounds in the muscle of cultured Taiwanese puffer Takifugu rubripes

SUMMARY: Seasonal variation in the level of extractive nitrogenous components was investigated in the muscle of puffer Takifugu rubripes cultured in two different areas of Taiwan. There were no seasonal and regional variations in the proximate composition of the fish. Of the free amino acids (FAA) in the muscle of puffer, the predominant one was taurine, followed by glycine, lysine, and alanine. Among nucleotide-related compounds, inosine monophosphate (IMP) and guanosine monophosphate (GMP) were the most prominent compounds. The total nucleotide-related compounds in the muscle of puffer were higher in July and November than those in the other months. The level of total taste-active components including glycine, alanine, arginine, GMP, IMP, and adenosine 5'-monophosphate was much higher in the muscle of puffer collected from July to January. Therefore, the puffer is probably more palatable in these periods.     

香料线滤棒爆口探索及其解决方案研究

为解决香料线滤棒(橙味香料)的爆口问题,进行滤棒成型试验。结果表明:橙味香料中的桔子油和甜橙精油会溶解滤棒搭口粘合剂热熔胶,从而引起滤棒爆口。针对此问题,采用了搭口冷热双胶线技术和伺服同步可调胶量的泵压式供胶系统,并结合对不同厂家提供的冷胶进行筛选,最终有效地解决了橙味香料引起的滤棒爆口。同时,为滤棒爆口和高透成形纸渗胶2个技术难题提供了解决思路。     

超高效液相色谱-串联质谱联用法测定香精香料中的香豆素和黄樟素

[目的]准确快速地测定香精香料中的香豆素和黄樟素。[方法]以60%乙醇水溶液为溶剂,样品经振荡萃取后,提取液经0.22μm滤膜过滤,采用超高效液相色谱-串联质谱联用法(UPLC-MS/MS)测定香豆素和黄樟素。[结果]该方法回收率的结果在95.0%~99.4%,日内、日间测定结果的变异系数分别小于6%和8%,香豆素和黄樟素的定量限分别为77.0和68.1μg/kg。[结论]该方法可有效去除杂质干扰,分析时间短,具有高灵敏度、高精密度、高准确度等优点,适用于香精香料中的香豆素和黄樟素的测定。     

不同萃取头萃取萝卜风味物质的GC-MS分析

采用PDMS/DVB和DVB/CAR/PDMS两种萃取头,以固相微萃取(SPME)法提取萝卜风味物质成分,经气相色谱-质谱联用(GC-MS)对风味物质成分进行鉴定,分析比较两种萃取头提取的风味物质成分差别,以确定适宜的萃取头。结果表明:两种萃取头的固相微萃取共检测到29种风味成分,PDMS/DVB提取数量为17种,DVB/CAR/PDMS为27种;PDMS/DVB萃取头所萃取的醇类、异硫氰酸酯类的数量比DVB/CAR/PDMS萃取头少2种,烷烃类少3种,杂环类少1种,酯类、酮类均未检测到;DVB/CAR/PDMS萃取异硫氰酸酯类、烷烃类、醛类、杂环类、酮类、醚类及醇类的灵敏度高,PDMS/DVB萃取芳香族类的灵敏度高。因此,根据获得风味物质数量、种类以及灵敏度,供试萃取头中,DVB/CAR/PDMS比PDMS/DVB更适于提取分析萝卜风味物质成分。     

稻米食味品质的相关性研究

统一鉴定南方稻区大面积推广的51个早籼稻品种的稻米品质后,进行了稻米食味品质与其他品质性状间的相关分析、逐步回归分析及通径分析。结果表明,稻米脂肪含量较其他品质性状对稻米食味品质有更大的影响,食用优质米的品质评价指标增加脂肪含量似更准确和完善。脂肪含量高、直链淀粉含量中等偏低、糊化温度低、胶稠度软或中等偏软、米粒延伸性好的稻米,食味品质好,这种品质性状的组合方式应该成为水稻品质育种的选择目标.本研究指出,提高脂肪含量、降低直链淀粉含量是改良稻米食味品质的关键,但直链淀粉含量并非越低越好。通过选择,将好的外观与优良的蒸煮、食味品质相结合是完全可能的.     

合成Hg-DADPA柱分离含硒或硫化合物的研究

[目的]通过化学方法合成一种新颖的Hg-DADPA柱,用于分离和富集植物及微生物体中硫硒修饰的化合物。[方法]使用二氨基二异丙基琼脂糖(DADPA)与对氯汞苯甲酸进行反应,得到Hg-DADPA色谱柱,用不同浓度的盐酸洗脱不同位置取代的硫或硒化合物;然后,通过Hg-DADPA色谱富集大肠杆菌(E.coli)的tRNA中含硫、含硒化合物,并且鉴定。同时,测试Hg-DADPA色谱柱分离后样品回收率。[结果]合成的Hg-DADPA柱通过0.002、0.005、0.5 mol/L HCl洗脱,可以分离尿苷三磷酸(UTP)、2-硫代尿嘧啶(2-SU)、2-硒代尿嘧啶(2-Se U)和4-硒代尿苷三磷酸(4-Se UTP)混合物,回收率均在90%以上。Hg-DADPA柱从大肠杆菌K12中选择性地富集到3个含硫修饰的核苷酸,经ESI和HR-MS鉴定为鸟嘌呤-2-硫代尿嘧啶核苷酸、腺嘌呤-3-硫代尿嘧啶核苷酸和鸟嘌呤-5-甲酰-2-尿嘧啶核苷酸。[结论]合成的Hg-DADPA柱对含硒、含硫化合物有很好的分离效果,且可反复使用,从而为植物、微生物中含硒或硫有机化合物的富集、分离提供一个简便的分离材料。     

不同成熟期白梨品种糖酸质量分数及风味评价

以成熟期不同的9个白梨品种为材料,通过测定果实糖和有机酸组分,研究早熟、中熟与晚熟品种间糖酸组分及质量分数的差异,在此基础上比较各品种间的果实风味指数。研究结果表明:成熟期不同的梨品种间果实糖酸组分及质量分数存在较大差异,并且在总糖或总酸质量分数差异不显著的条件下,不同品种间果糖、葡萄糖和蔗糖等糖组分质量分数,苹果酸、柠檬酸和琥珀酸等有机酸组分质量分数存在显著差异;与糖酸比相比,果实风味指数更能反映果实的真实风味。从果实风味指数角度来考虑,早熟品种中‘雪青’风味最佳,中熟品种‘黄冠’最佳,晚熟品种中则以‘雪花梨’最佳。