微纳米气泡在食品工业中的应用与前景

微纳米气泡是将气体分散在溶液中,形成的直径在几十纳米到几十微米之间的微小气泡颗粒。相比于普通气泡（≥600 μm）,由于微纳米气泡尺寸小易受到溶液分子布朗运动影响,具有稳定性强、溶液中存在时间长、气-液界面富含负电荷、气泡崩塌过程中能形成自由基等理化特性被广泛应用于环境污染治理、农业种植、材料科学以及医学等领域。然而,微纳米气泡技术在食品工业中应用仍处于研究阶段。该研究将主要从微纳米气泡的形成过程、制备方法、气泡特性以及目前该技术在食品工业中的应用进行阐述,并对其在食品领域的发展方向以及应用前景进行展望,以期促进微纳米气泡技术在食品工业中的研究和开发应用。     

针织加热织物的热电性能

为研究镀银导电长丝在积极保暖服装中应用的可行性,对导电长丝的热电稳定性进行测试,并采用镀银导电长丝和涤纶短纤纱制作了3种不同结构的针织加热织物以研究其加热效果。结果显示,镀银导电长丝的电阻随着老化时间和老化温度的增加而增大。通过提取和分析镀银导电长丝和针织加热织物表面的红外温度图像,得出其表面最高平衡温度与功率消耗密度呈正比关系,且针织加热织物的功率消耗密度与模拟服装内部的平衡温度也高度线性相关。     

黄粉虫幼虫粉酶解及体外抗氧化性研究

主要研究了Alcalase蛋白酶水解脱脂黄粉虫幼虫粉的工艺,并对水解产物的体外抗氧化能力进行测定.在单因素基础上以还原力为指标设计正交试验得到水解最佳条件为:温度60℃,pH值8.5,加酶量150μL,反应时间100 min.抗氧化试验结果表明,脱脂黄粉虫幼虫粉水解液清除1,1-二苯基-2-苦基苯肼(DPPH)自由基和羟自由基的半抑制率(IC_(50))分别为0.45 mg/mL和4.1 mg/mL,分别是VC的IC_(50)值的112.5倍和19.5倍,还原能力是VC的1/100.将水解前后的脱脂黄粉虫幼虫粉溶液进行高效毛细管电泳(HPCE)测定,测定结果表明,经Alcalase蛋白酶水解后,溶液中可溶性组分增多.     

钝顶螺旋藻藻蓝蛋白的稳定性试验研究

用冻融的方法制备钝顶螺旋藻(Spirulina platensis)藻蓝蛋白并对纯化后的藻蓝蛋白稳定性进行了初步研究。提取后的粗提液经羟基磷灰石柱层析纯化后其纯度(A621／A280)达3.1温度、酸碱度、乙醇对藻蓝蛋白稳定性有较大影响；NaCl、苯甲酸钠、柠檬酸等食品添加剂对其稳定性影响较小。     

超声波对螺旋藻蛋白质酶解促进作用的试验研究

通过螺旋藻蛋白质的酶解技术,可以改善螺旋藻的水溶性。为了提高螺旋藻蛋白质酶解的效率,研究了超声波技术对酶解过程的促进作用。在同样的试验因素与水平下,进行了对比正交优化试验,结果表明,未经超声波预处理,水解率为52.25%;在超声波处理时间为20min、底物浓度为3%、温度为40℃、pH值为10、恒温酶解为7h的条件下,经过超声波预处理,水解率可达67.05%,水解率提高近15个百分点。     

Evaluation of two commercial lateral-flow test kits for detection of animal proteins in animal feed

Performance characteristics were evaluated for two lateral-flow test kits, Reveal for Ruminant in Feed (Neogen Corporation) and FeedChek (Strategic Diagnostics Inc.), designed to detect ruminant or terrestrial animal proteins in feeds. The stringent acceptance criteria used were developed by the Center for Veterinary Medicine Office of Research to identify test kits with comparable selectivity and sensitivity to microscopy and PCR assay, the analytical methods used by the U.S. Food and Drug Administration (FDA). Guidelines were developed for evaluating the selectivity, sensitivity, ruggedness, and specificity of these kits. These guidelines further stated that ruggedness and specificity testing would be performed only after a test passed both the selectivity and sensitivity assessments. Acceptance criteria for determining success were developed using a statistical approach requiring 90% probability of achieving the correct response, within a 95% confidence interval. A minimum detection level of 0.1% bovine meat and bone meal, consistent with the sensitivity of the methods used by the FDA, was required. Selectivity was assessed by testing 60 dairy feed samples that contained no added animal proteins; sensitivity was determined by evaluating 60 samples (per level of fortification) of the same feed that contained 0.025, 0.05, 0.1, 0.25, 0.5, 1, or 2% bovine meat and bone meal. The Reveal test passed the selectivity assessment but failed the sensitivity assessment, detecting only samples fortified at the 2% level and then only 17 to 33% of those samples, when read according to the label directions. The FeedChek test passed the sensitivity assessment but failed the selectivity assessment, with rates for false-positive results ranging from 34 to 38%, depending on the user. The sensitivity of the Reveal test was affected by the concentration of trace minerals present in the feed; concentrations toward the high end of the normal range prevented the detection of true positive feed samples containing bovine meat and bone meal. Better sensitivity assessments were obtained when lamb meal was used either alone or in combination with bovine meat and bone meal. The FeedChek test was not affected by the concentration of trace minerals or by the type of animal meal used. These results indicate that neither of the two tests is adequate for routine regulatory use.     

Characterization of a polymerase chain reaction-based approach for the simultaneous detection of multiple animal-derived materials in animal feed

In this study, a polymerase chain reaction (PCR) primer set capable of amplifying a mitochondrial DNA segment of multiple species (cattle, sheep, goats, deer, and elk) whose rendered remains are prohibited from being fed to ruminants was characterized. However, the primer set also amplifies DNA derived from the rendered remains of pigs and horses, which are exempt from the feed ban. PCR amplicons derived from pig DNA have a restriction endonuclease site recognized by Hinf1, while the horse DNA-derived amplicon has a unique restriction endonuclease site recognized by HypCH4III. This "universal" PCR primer produced an amplicon with DNA extracted from dairy feed containing either bovine meat and bone meal or pig blood meal. Enzymatic digestion of the PCR amplicons from these feed samples with Hinf1 resulted in cleavage products only from samples containing pig blood meal. However, Hinf1 digestion of these amplicons was not complete. Further analysis of the pig blood meal with primers specific for bovine or porcine DNA demonstrated the presence of both bovine- and porcine-derived DNA. Enzymatic digestion confirmed these findings. Additional testing was conducted with dry dog food samples labeled as containing either lamb, chicken, turkey, or chicken and fish. The universal PCR primer produced an amplicon only for the dog food containing lamb meal. This paper is the first to describe a simplified approach for the detection of the prohibited species of concern in the feed ban.     

Assessment of two enzyme-linked immunosorbent assay tests marketed for detection of ruminant proteins in finished feed

The performance characteristics of two enzyme-linked immunosorbent assay (ELISA) test kits, ELISA Technologies' MELISA-Tek test and Tepnel BioSystems' BioKit for (Cooked) Species Identification test, designed to detect ruminant proteins in animal feed, were evaluated. The test kits were evaluated by using acceptance criteria developed by the U.S. Food and Drug Administration's Center for Veterinary Medicine Office of Research for evaluating selectivity, sensitivity, ruggedness, and specificity. The acceptance criteria for determining success used a statistical approach requiring a 90% probability of achieving the correct response within a 95% confidence interval. In practice, this measure requires the test to achieve the correct response 58 times for every 60 samples evaluated, or a 96.7% accuracy rate. A minimum detection level of 0.1% bovine meat and bone meal (BMBM) was required, consistent with the sensitivity of the analytical methods presently used by the U.S. Food and Drug Administration. Selectivity was assessed by testing 60 dairy feed samples that contained no added animal proteins; sensitivity was determined by evaluating 60 samples (per level of fortification) of this same feed that contained 0.025, 0.05, 0.1, 0.25, 0.5, 1, or 2% BMBM. The MELISA-Tek test passed the acceptance set-point criteria for selectivity assessment but failed the sensitivity assessment at all levels except at the 2% level. The MELISA-Tek test came close to passing at the 1% level, detecting true-positive findings at a rate of 93%, but failed at lower levels, in spite of the label claim of 0.5% sensitivity. The BioKit for (Cooked) Species Identification test detected only 2 of 17 samples fortified at the 2% BMBM level and failed to detect any other BMBM-fortified samples. The results of this evaluation indicate that neither test is adequate for regulatory use.     

Evaluation of the bactericidal characteristics of nano-copper oxide or functionalized zeolite coating for bio-corrosion control in concrete sewer pipes

The bactericidal characteristics of nano-copper oxide or functionalized zeolite coated concrete pipes against Acidithiobacillus thiooxidans were studied by measuring the temporal variation of bacterial dry cell weight measurement, cellular Adenosine Triphosphate production, as well as oxygen uptake rate of the aforementioned bacterium. Uncorroded (UC), severely corroded (SC), and moderately corroded (MC) concrete pipes were electrochemically coated with a nano-copper oxide, while another uncorroded concrete pipe was used to apply functionalized zeolite coating (Z2). Specimens were characterized by field emission-scanning electron microscopy, and optical microscopy. Oxygen uptake rate of the bacterium was the highest in UC followed by the MC. Oxygen uptake rate and cellular Adenosine Triphosphate decreased progressively in Z2 and SC throughout the duration of the experiment due to decline in live bacterial cell. The maximum bacterial specific growth rate was 1.1 × 10⁻² day⁻¹ for both UC and MC, with a decay rates varying from 1.4 × 10⁻² to 2.6 × 10⁻² day⁻¹. The minimum concentration limits for the inhibition of the bacterium in the nano-copper oxide coated concrete pipes ranged from 2.3 mg to 2.6 mg Cu per mg dry cell weight.