吸附烹饪油烟丙烯酸酯树脂的研制

利用悬浮聚合方法制备了一种吸附烹饪油烟的丙烯酸酯树脂。采用单因素实验方法,探讨了丙烯酸酯单体种类及用量、引发剂用量、分散相用量、反应温度、搅拌速度等因素对树脂静态吸附油烟率的影响。结果表明,当丙烯酸用量为10mL,甲基丙烯酸十二酯为25mL,过氧化苯甲酰(BPO)为0.4g,5%(质量分数)聚乙烯醇(PVA-1799)溶液为100mL,二乙烯基苯的用量为0.39mL,搅拌速度为600r/min,反应温度为85℃,反应时间为5h时,所得树脂在室温下静态吸附油烟率可达300%;在油烟流速为350L/h,吸附油烟6h时,油烟去除率达97%以上,树脂吸附油烟率为29.4%。     

Changes in the amounts of water-soluble umami-related substances in porcine longissimus and biceps femoris muscles during moist heat cooking

Time course changes in amounts of glutamic acid, total free amino acid, inosine monophosphate (IMP), and 2%-trichloroacetic acid-soluble oligopeptides in whole, muscle only, and cooking juice during wet-heat cooking in pork longissimus and biceps femoris muscles were investigated because the movements of umami-relevant substances during cooking treatment had not previously been clarified in detail. The amounts of glutamic acid, total free amino acid, and IMP significantly (P<.05) decreased and increased in muscle and cooking juice during 180min of cooking, respectively. The whole amounts of glutamic acid and total free amino acid remained unchanged during cooking treatment. The whole amount of IMP, however, increased significantly at 10min of cooking (P<.05) and was maintained after the 10-min period. The extramuscular oligopeptides amount increased significantly in response to the cooking treatment (P<.05). The intramuscular amount of oligopeptides decreased at 30min of cooking but increased significantly (P<.05) after 60min. The whole meat oligopeptides amount increased significantly during a 180-min cooking treatment (P<.05). These results indicate that glutamate, total free amino acid, and IMP were released from the muscle during cooking, and that IMP levels increased in the initial phase of cooking. In addition, oligopeptides increased during wet-heat cooking of pork muscles.     

固相萃取-气相色谱质谱法测定食用油中邻苯二甲酸酯

建立了固相萃取-气相色谱质谱法测定食用油中邻苯二甲酸酯的分析方法。以正己烷为提取剂萃取试样中的邻苯二甲酸酯,样液经中性氧化铝自组装固相萃取柱净化后进行GC/MS测定分析。采用选择离子扫描方式,用外标法进行定量分析。方法的检出限(S/N=3)为1~6μg/kg。在加标水平为50μg/kg时,平均回收率为67.3~107%,相对标准偏差(RSD)为3.6~6.1%;在加标水平为100μg/kg时,平均回收率为67.5~103%,相对标准偏差(RSD)为3.2~6.2%。本方法简便、快速地实现了食用油中邻苯二甲酸酯的检测。     

海鱼中5种形态有害元素在不同烹调方式下的加工系数研究

目的 研究我国广东省主要海产鱼类在不同典型烹调加工方式下5种有害元素的加工系数,为提升我国食品安全风险评估结果的精确性提供评估参数。方法 基于广东省2个沿海地区居民常消费的19种海产鱼类,随机采样处理后分为清蒸组、油煎组、烘烤组和1个对照组（未烹调组）,检测其总汞、甲基汞、总砷、镉、铅在烹调处理前后浓度的变化,并分别计算每种海鱼中总汞等5种形态有害元素的加工系数。结果 油煎和烘烤处理后海鱼中总汞、甲基汞、总砷、镉的浓度显著高于未烹调组（P<0.05）,而清蒸后海鱼中铅的浓度显著低于未烹调组（P<0.05）。此外不同种类海鱼,相同烹调方式下其有害元素的加工系数存在一定差异,煎和烤的加工方式下海鱼中重金属的加工系数高于清蒸方式。结论 海鱼中总汞、甲基汞、总砷、镉和铅的浓度经过烹调加工后可发生显著变化。风险评估时,应结合评估情形需要,选择合适的加工系数提高风险评估精确度。     

地沟油水解法基于浮选的再生技术研究*

本文选择食堂废弃的地沟油为研究对象,通过控制水解条件,获得不同性质的地沟油改性捕收剂。分别探究温度、催化剂、乳化剂用量等因素对地沟油水解的影响规律,确定其最佳的改性条件。采用接触角测定表征地沟油的改性效果,通过比较地沟油改性捕收剂在固废浮选方面的应用效果。结果表明地沟油改性剂具有一定的捕收作用,在浮选分离领域,可替代传统脂肪酸类捕收剂及非极性烃类捕收剂的使用。     

Soaking Conditions Affect the Contents of Tocopherols,Tocotrienols, and γ-Oryzanol in Pigmented and Non-Pigmented Brown Rice

Tocopherols (Toc), tocotrienols (T3), and γ‐oryzanol (GO), important lipid antioxidants in rice, are known to possess various pharmacological properties. In this study, our aim was to examine the effects of soaking conditions on the extractable contents of Toc, T3, and GO in cooked pigmented (PBR) and non‐pigmented brown rice (non‐PBR). The results showed that Toc, T3, and GO concentrations in non‐PBR peaked after soaking at 25 °C for 120 min, whereas soaking conditions showed minimal effects on these compounds in PBR. In non‐PBR, high Toc, T3, and GO levels were also noted in the treatments at higher soaking temperatures (45 and 55 °C) with a shorter soaking time (less than 60 min). The GO level in both cultivars was at least ten times greater than the total vitamin E content. Vitamin E analogues having concentrations greater than 10 mg/kg in PBR and non‐PBR were γ‐Toc and γ‐T3, and α‐Toc and γ‐T3, respectively. This study concludes that presoaking and cooking processes can improve the extractable contents of Toc, T3, and GO in cooked PBR and non‐PBR, and the extraction yield of these bioactive compounds was significantly different between cultivars.     

Effect of cooking on the antioxidant properties of coloured peppers

Pepper (Capsicum annum L.) has long been recognized as an excellent source of antioxidants, being rich in ascorbic acid and other phytochemicals. This study was conducted to investigate the effect of different cooking methods on the antioxidant properties of coloured peppers. Six varieties of peppers were subjected to different cooking methods, such as microwave heating, stir-frying and boiling in water, for 5 min individually. The cooked and raw peppers were analyzed for radical-scavenging activity (RSA) and total polyphenol content (TP) using 1,1-diphenyl-2-picrylhydrazyl–high-pressure liquid chromatography (DPPH)–HPLC and Folin-Ciocalteu methods, respectively. The samples were also evaluated for ascorbic acid content (AsA) by HPLC. Total carotenoid content was determined spectrophotometrically. Results suggest that there is no significant (P > 0.05) difference in RSA, TP, AsA and total carotenoid contents between the cooked and raw peppers when processed for 5 min. However, the cooked peppers show marked differences (P < 0.05) in the RSA, TP and AsA when cooked for 5 min in boiling water with further reduction observed after boiling for 30 min. This may be due to the leaching of antioxidant compounds from the pepper into the cooking water during the prolonged exposure to water and heat. Therefore, it is vital to use less water and cooking time and also to consume the water used for boiling so as to obtain the optimum benefits of bioactive compounds present in peppers. It is concluded that microwave heating and stir-frying without using water are more suitable cooking methods for pepper, to ensure the maximum retention of antioxidant molecules.     

Effect of preliminary processing and method of preservation on the content of selected antioxidative compounds in kale (Brassica oleracea L. var. acephala) leaves

Vitamin C and polyphenol content as well as total antioxidative activity were investigated in fresh leaves of kale; in leaves after blanching or cooking; and in frozen and canned leaves. In 100 g fresh matter, kale leaves contained 384.9 mg polyphenols and 112.1 mg vitamin C, with a Trolox equivalent antioxidant capacity (TEAC) level of 1175 μM Trolox. Of the polyphenols identified in kale leaves, ferulic acid occurred in the highest amount (240.44 mg/100 g, constituting 62% of total polyphenols). Freezing was a better method of preserving kale leaves since the loss of nutritive constituents was lower than in the case of canning. Depending on preliminary processing and storage temperature, after one-year storage frozen leaves contained 82.9–171.3 mg polyphenols and 39.3–65.4 mg vitamin C, with TEAC at the level of 501–681 μM Trolox in 100 g. In canned leaves these values were: 91.3–94.1 mg polyphenols, 16.1–19.3 mg vitamin C and 268–293 μM Trolox.     

Application of native and phosphorylated tapioca starches in potato starch noodle

Summary Characteristics of potato starch noodles substituted with native, phosphorylated and commercial phosphorylated (MTS283) tapioca starches were evaluated. Substitution of up to 17% with phosphorylated tapioca starch or up to 35% with MTS283 improved the quality of potato starch noodles. The resulting noodles were transparent and less brittle when uncooked, and were moderately elastic, less sticky and experienced lower cooking loss and less swelling when cooked. Substitution with native tapioca starch of up to 17% was also possible, but the uncooked noodles were less transparent and the cooked noodles swelled more and were less elastic.