含氰糖苷类作物脱毒技术及其检测方法的研究进展

氰糖苷是一种毒性很强的化合物,在食用前需采取有效的脱毒方式除掉氰糖苷化合物,减少其在作物中的残留量。本文对作物中氰糖苷的不同脱毒技术即湿法脱毒技术、干法脱毒技术、微波脱毒技术、溶剂提取脱毒技术、挤压膨化脱毒技术和生物法脱毒技术等进行了全面的评述;对氰糖苷、氢氰酸的检测方法进行了综述;为广大科研工作者以后选育一种低氰糖苷品种作物,筛选一种脱毒效率高、操作简单、适用性强、安全性高的脱毒工艺奠定了基础。      

响应面法优化亚麻籽氢氰酸提取条件

为了提高亚麻籽中的氢氰酸含量检测的效率,同时确保其准确性,用响应面法对异烟酸-巴比妥酸比色法前处理中的提取方法进行了优化。运用Design Expert 7.0数据分析软件在单因素实验的基础上采用3因素3水平的响应面分析法,建立了氢氰酸提取率与各影响因子的回归方程。结果表明:氢氰酸的最佳提取条件为液固比50∶1（m L/g）、提取时间45 min、氢氧化钠吸收液浓度10 g/L,氢氰酸实际提取率可达96.12%。结论:此方法真实可靠,可用于大批量检测亚麻籽中的氢氰酸含量。      

Mycotoxins and cyanogenic glycosides in staple foods of three indigenous people of the Colombian Amazon

A study was conducted to determine the incidence and levels of mycotoxins in the main staple foods of three indigenous people of the Colombian Amazon. A total of 20 corn, 24 rice and 59 cassava samples were analysed by a multi-analyte liquid chromatography-tandem mass spectrometry method covering the major classes of mycotoxins. In addition, cassava samples were also analysed for cyanogenic glycosides. The indigenous Amazon communities tested are exposed to potentially carcinogenic mycotoxins (particularly aflatoxins), as well as other mycotoxins, mainly through the intake of locally grown corn. Citrinin content in this corn was unusually high and has not been reported elsewhere. Two cassava samples contained high levels of cyanogenic glycosides. It is strongly recommended not to grow corn in the Amazon but instead purchase it from vendors capable of guaranteeing mycotoxin levels below the maximum allowable concentration in Colombia.     

食用木薯块根及其制品中生氰糖苷检测方法的建立与应用

生氰糖苷含量的高低对评估食用木薯块根及其制品的食用安全性及其重要。以木薯块根和木薯粉为试材,本研究建立了亚麻苦苷和百脉根苷2种生氰糖苷（Cyanogenic Glycosides,CNGs）的快速提取和高效液相色谱-蒸发光散射（HPLC-ELSD）检测的方法,分析了不同品种木薯块根、木薯粉及其制品中CNGs含量变化。结果表明,食用木薯块根及木薯粉中CNGs提取最佳的硫酸溶液浓度分别为0.025和0.100 mol/L;HPLC-ELSD检测方法可有效分离亚麻苦苷和百脉根苷,其浓度在4.1～820.0 mg/L和2.5～250.0 mg/L范围内线性相关性较好,相关系数（r）分别达到了0.9996和0.9993,检测限（LOD）分别为2.1和0.5 mg/kg,定量限（LOQ）分别为8.2和2.0 mg/kg;该方法重复性和样品稳定性的标准偏差（RSD）都低于5.0%;木薯块根和木薯粉中2种CNGs的平均加标回收率分别在89.3%～96.3%和107.5%～114.9%之间,重复间RSD小于3.4%。样品验证结果表明:不同的木薯品种CNGs含量差异较大;种植8～9个月的木薯制备木薯粉CNGs含量较低;蒸煮加工方式可有效清除木薯食品中CNGs。本方法操作简单、稳定性较好、准确度高,在食用木薯块根及其制品中CNGs的分析与评价等研究方面具有较强的应用前景。     

复合有机酸催化大豆异黄酮糖苷水解成苷元的工艺研究

通过单因素实验和正交实验,以水解率为评价指标,研究复合有机酸催化大豆异黄酮糖苷水解成苷元的工艺参数。结果表明,最佳水解工艺为:反应温度135℃,反应时间为160 min,复合酸配比(苹果酸∶柠檬酸)为4∶3,水解率达到97.0%以上。复合有机酸催化水解工艺绿色环保,水解产物无需分离,可直接作为保健食品原料,具有较高的应用价值。     

Pesticide content of infant formulae and weaning foods available in New Zealand

A survey of the pesticide content of 25 commercially available infant formulae and 30 weaning foods available in New Zealand was undertaken in 1996. It included a representative mixture of imported and New Zealand manufactured infant foods. Three different pesticide screening techniques were used: a high-sensitivity organochlorine screen was carried out on all infant formulae, while a multiresidue screen (organochlorine and organophosphorus pesticides, synthetic pyrethroids, carbamate pesticides, fungicides and herbicides), and a specific screen for dithiocarbamate fungicides were both carried out on all weaning foods and on soy-based infant formulae. All results are expressed on a ready-to-feed basis. Extremely low levels of residues of three organochlorine compounds (p,p'-DDE, p,p'-DDT and dieldrin) were detected in infant formulae samples. Residues of p,p'-DDE were found in seven of 20 milk-based infant formulae at concentrations ranging from 0.03 to 0.5 μg kg^-1. Residues of p,p'-DDT were found in one imported milk-based infant formula at 0.7 μg kg^-1, and dieldrin residues were detected in four of five soy-based infant formulae at concentrations ranging from 0.05 to 0.08 μg kg^-1. The multiresidue pesticide screen detected low levels of residues of two organophosphorus pesticides; azinphos-methyl in one soy-based infant formula at a level of 22 μg kg^-1 and pirimiphos-methyl in two cereal-based weaning foods at concentrations of 5 and 14 μg kg^-1. None of the other approximately 140 pesticides (including fungicides and herbicides) included in the multiresidue screen were detected in any weaning foods or soy-based infant formulae, at a detection limit of 10 μg kg^-1. No residues of dithiocarbamate fungicides were detected in any product analysed, at a detection limit of 100 μg kg^-1.     

不同茶类中黄酮醇苷酸水解条件的优化及酸水解前后3种黄酮醇含量的测定

目的 建立高效液相色谱法（High performance liquid chromatography, HPLC）同时测定不同茶类中黄酮醇的含量,并优化茶叶中黄酮醇苷酸水解成黄酮醇（杨梅素、槲皮素、山柰酚）的条件,以此测定不同茶类中三种类型黄酮醇苷元的含量。方法 样品经70%甲醇水（V:V）提取后,用盐酸（16%）-甲醇溶液进行酸水解,再经乙酸乙酯萃取、浓缩、复溶至相同体积;酸水解前后的样品溶液均用HPLC对黄酮醇进行定量分析并用超高效液相色谱-串联质谱(ultra-performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)对黄酮醇苷进行定性分析。 结果 3种黄酮醇在3.125~100 μg/mL的浓度范围内具有较好的线性关系（r2≥0.9976）,优化后的方法的重复性、稳定性、精密度较好（相对标准偏差（RSD）≤4%）。六大茶类中黄酮醇苷的最佳酸水解条件：水解时间为1 h,水解温度为80 ℃,盐酸 (16%)-甲醇溶液最佳比例为1:2 (V:V)。 结论 本研究优化了茶叶中黄酮醇苷酸水解的方法,并利用HPLC测定了六大茶类酸水解前后黄酮醇的含量。方法处理简单、结果准确可靠,适用于茶叶中黄酮醇及其苷类物质的分析。     

Ensilage as a means of reducing the concentration of cyanogenic glycosides in the pods of Acacia sieberiana and the effect of additives on silage quality

Cyanogenic glycosides are anti‐nutritional components capable of liberating hydrogen cyanide, a respiratory poison that has been reported to be responsible for the death of livestock that browse some Acacia species containing these compounds. The objective of the study was to improve the nutritive value of the pods of Acacia sieberiana by reducing their contents of cyanogenic glycosides through ensiling, and to examine the influence of various levels of added molasses and urea on the aerobic stability of the silage. In experiment 1, laboratory silages, prepared by mixing ground pods with water in two ratios (60:40 and 40:60 w/w pod material:water), were put into 250 ml polythene bottles, ensiled for 4, 7, 14, 21, 28 or 35 days and analyzed for cyanide. In experiment 2, silages prepared as described above but using only one of the ratios (40:60), and with the addition of molasses (0, 30 or 60 g kg^?1) and urea (0, 2.5 or 50 g kg^?1) were included in a 3 × 3 factorial design, to study the effects of these additives on the stability of the silage. The period of ensilage was 14 days. In experiment 3, the concentrations of molasses and urea were modified to 0, 45 or 90 g kg^?1 and 0, 7.5 or 15 g kg^?1, respectively, and the period of ensilage was extended to 45 days. The parent material contained 130.6 mg CN kg^?1 DM and ensiling the material for 35 days reduced the concentration to 18.1 mg CN kg^?1 DM. Moisture content at ensiling significantly (P < 0.001) affected the concentration of cyanide in the stored silages. Silages opened after 14 days were unstable irrespective of the use of additives. However those with combined urea and molasses exhibited a slow rate of deterioration and low fungal counts. Extending the period of ensiling to 45 days improved the aerobic stability of all the silages. The addition of urea significantly (P < 0.001) increased the pH, crude protein content, gross energy and fermentation acids while molasses treatment increased (P < 0.001) the lactic acid and ash content of the silages. Ensiling ground pods for 45 days was enough to reduce the cyanide content to non‐toxic levels and produced a silage which was aerobically stable, while the inclusion of additives further improved the quality of the silages. Copyright © 2004 Society of Chemical Industry     

Barriers impairing mineral bioaccessibility and bioavailability in plant-based foods and the perspectives for food processing

Abstract

Plant-based foods gain more importance since they play a key role in sustainable, low-meat and healthy diets. In developing countries, these food products, especially legumes and cereals, are important staple foods. Nevertheless, the question arises on how efficient they are to deliver minerals and if it is useful to encourage their consumption to reduce the prevalence of mineral deficiencies? This review paper focuses on the discrepancy between the mineral content and the amount of minerals that can be released and absorbed from plant-based foods during human digestion which can be attributed to several inherent factors such as the presence of mineral antinutrients (phytic acid, polyphenols and dietary fiber) and physical barriers (surrounding macronutrients and cell wall). Further, this review paper summarizes the effects of different processing techniques (milling, soaking, dehulling, fermentation, germination and thermal processing) on mineral bioaccessibility and bioavailability of plant-based foods. The positive impact of these techniques mostly relies on the fact that antinutrients levels are reduced due to removal of fractions rich in antinutrients and/or due to their leaching into the processing liquid. Although processing can have a positive effect, it also can induce leaching out of minerals and a reduced mineral bioaccessibility and bioavailability.     

Intake and risk assessment of nitrate and nitrite from New Zealand foods and drinking water

Exposure to excess nitrite is a potential health risk for humans. One hundred meat and processed foods and 100 vegetable samples purchased from New Zealand retail outlets were prepared as for consumption and analysed for nitrite and nitrate concentration using a standard, validated methodology. Nitrate concentrations ranged from less than the limit of detection (LOD = 5 mg kg^-1) in cheddar cheese and cream cheese-based dips to 3420 mg kg^-1 in lettuce. Nitrite was detected in half the processed foods and meats analysed (levels up to 119 mg kg^-1), but detected in only one vegetable sample above the LOD (broccoli at 27 mg kg^-1 nitrite). Concentration data were combined with 24 h dietary recall information to generate 4398 individual adult daily exposure scenarios for exogenous nitrite and nitrate including a contribution from water assessed from 1021 drinking water samples. The mean adult daily intake of exogenous nitrate and nitrite from food and water combined was 16 and 13% of the Acceptable Daily Intake (ADI), respectively, and therefore should not pose a health risk for the average consumer. A maximally exposed New Zealand adult is estimated to have an intake of up to seven times the ADI for nitrate. When the endogenous conversion of nitrate to nitrite is taken into account, approximately 10% of people with an average rate of conversion and half of all people with a high rate of conversion are estimated to exceed the ADI. Either the ADI is inappropriate and needs to be re-evaluated, or those individuals who have a high rate of conversion of nitrate to nitrite are at risk to adverse effects of nitrite exposure.     

Determination of total nitrogen and cyanide nitrogen in cassava

Heating of intact cassava leaves causes liberation of hydrogen cyanide. This phenomenon appears to be caused by β-glucosidase-catalysed decomposition of the cyanogenic glycosides linamarin and lotaustralin. Because of these losses, many previously determined values for total nitrogen in cassava (and other cyanogenic plants) are probably in error as plant materials used for Kjeldahl determinations are often dried at 70–90°C. Liberation of cyanide from intact cassava leaves by heating at 80°C is more complete than liberation by the homogenisation methods commonly used. Homogenisation of cassava leaf tissues with liquid nitrogen or dry ice gives somewhat lower values, and these materials are often not readily available in areas where cassava is studied. The basis of a relatively simple procedure for the isolation of hydrogen cyanide from cassava leaves is suggested.     

Glyphosate residues in Swiss market foods: monitoring and risk evaluation

A total of 243 samples of diverse foodstuffs were analysed for glyphosate and aminomethylphosphonic acid (AMPA) using a liquid chromatography triple quadrupole mass spectrometry (LC/MS/MS) method with a relatively low limit of quantification in the range of 0.0005–0.0025 mg kg^?1. Main contributors for dietary glyphosate and AMPA intake were cereals and pulses. The results suggest that pasta is a very important foodstuff for dietary glyphosate residue intake in Switzerland. Interestingly all samples of wine, fruit juice and nearly all samples of honey tested positive for glyphosate although at very low levels. A dietary risk assessment was conducted. Food products for analysis were not selected purely at random, rather products were selected for which high levels of glyphosate residues were suspected. However, even in samples where high residue levels were expected, no exceedances of maximum residue levels were found. Consequently, human exposure did not exceed neither acceptable daily intake nor acute reference dose. Therefore, glyphosate residues found in the sampled foodstuffs from the Swiss market were of no concern for human health.     

干红葡萄酒中总糖测定方法的改进

通过对干红葡萄酒中酒精、蛋白质、氨基酸等对总糖测定是否有影响,以及滴定时如何使滴定终点明显易判断进行研究。结果证明,测定干红葡萄酒中总糖时要先除酒精,酒中的蛋白质、氨基酸等对总糖的测定无影响,滴定时将水解液与葡萄糖标准溶液按1：2混合后进行滴定可使终点明显、易判断。     

四种蛋白酶对牡蛎的酶解效果研究

以太平洋牡蛎(Oxtrea rivularis Gould)为研究对象,研究了四种蛋白酶酶解对太平洋牡蛎的氨基态氮、总酸、矿质元素及牛磺酸含量的影响。通过比较酶解过程中总酸和氨基氮含量变化可知,枯草杆菌中性蛋白酶的水解程度最高,其次为风味蛋白酶,木瓜蛋白酶和菠萝蛋白酶的水解程度较低。对酶解过程中酶解液内所含牛磺酸及Zn、Cu、Se的研究。结果表明,木瓜蛋白酶酶解液中牛磺酸含量最高,为4.01mg/m L,风味蛋白酶酶解液中Zn、Cu、Se含量最高,分别为67.40、26.73μg/m L、270.92μg/L。为优化牡蛎酶解工艺条件或以牡蛎为原料制备富硒饮料等提供了理论基础。      

Willingness to adopt a more plant-based diet in China and New Zealand: Applying the theories of planned behaviour,meat attachment and food choice motives

The purpose of this study is to explore the significant factors that drive consumers’ willingness to adopt a more plant-based diet, in both an Asian developing country (China) and a Western developed country (New Zealand), on the basis of three theories: meat attachment factors, the theory of planned behaviour and food choice motives. The data were collected through online surveys in China (n = 604) and New Zealand (n = 581). Confirmatory factor analysis and structural equation modelling were used for the data analysis. Consumers’ willingness to adopt a more plant-based diet was significantly linked to all the four meat attachment factors (Hedonism, Affinity, Entitlement and Dependence), four factors based on the Theory of Planned Behaviour (Subjective norms, Personal norms, Perceived behavioural control and Attitudes), and one food choice motive (Environmental concern). There were differences between China and New Zealand in the impact of the meat attachment factors and the theory of planned behaviour factors on the willingness to adopt a more plant-based diet.     

Comparison of requirements for using health claims on foods in the European Union,the USA,Canada, and Australia/New Zealand

Nutrition is recognized as one of the leading factors influencing the growing incidence of noncommunicable diseases. Despite society experiencing a global rise in obesity, specific populations remain at risk of nutrient deficiencies. The food industry can use health claims to inform consumers about the health benefits of foods through labeling and the broader promotion of specific food products. As health claims are carefully regulated in many countries, their use is limited due to considerable investments required to fulfill the regulatory requirement. Although health claims represent a driving force for innovation in the food industry, the risk of misleading of consumers need to be avoided. The health claim scientific substantiation process must be efficient and transparent in order to meet the needs of companies in the global market, but should be based on strong scientific evidence and plausible mechanisms of actions, to ensure highest level of consumer protection. The objective of this review is to compare the possibilities for using health claims on foods in the European Union, the USA, Canada, and Australia and New Zealand. In particular, we focused on differences in the classification of claims, on the scientific substantiation processes and requirements for health claims use on foods in the selected regions. Reduction of disease risk (RDR) claims are associated with relatively similar procedures and conditions for use, whereas several notable differences were identified for other types of claims. In all cases, RDR claims must be approved prior their introduction to the market, and only a few such claims have been authorized. Much greater differences were observed concerning other types of claims.     

Risk assessment of antimony,barium, beryllium,boron, bromine,lithium, nickel,strontium, thallium and uranium concentrations in the New Zealand diet

ABSTRACT

Identifying and monitoring dietary toxicants is an important component of contemporary food safety systems. To characterise their potential dietary risks, analysis was undertaken of 10 elements: antimony, barium, beryllium, boron, bromine, lithium, nickel, strontium, thallium and uranium in 132 different food types. All 10 elements were reported as quantified in aportion of the analysed foods, with prevalence ranging from less than 1% for antimony to 98% for barium. Dietary exposure assessment was undertaken for 10 New Zealand population cohorts using apublished simulated diet, and proportionality of food groups to total exposure identified. Characterisation against health-based guidance values identified no dietary risk from exposures to beryllium, boron, bromine, lithium, strontium and uranium to any of the population cohorts. For antimony and thallium, the exposure range for infants was calculated to exceed the health-based guidance value, and for barium and nickel, all mean exposures were above the health-based guidance value for younger population cohorts. Although some conservatism in applying upper-bound mean exposures reduces the likelihood of asignificant dietary risk, further laboratory method development and analysis of these elements in the New Zealand diet would be beneficial to ensure protection of New Zealand public health.     

Flavour development in dairy cream using fish digestive lipases from Chinook salmon (Oncorhynchustshawytscha) and New Zealand hoki (Macruronusnovaezealandiae)

Digestive lipases from Chinook salmon and New Zealand hoki were evaluated as flavour modifying agents in dairy products. Cream was incubated either with fish lipase or commercially available lipases used in dairy flavour development – calf pregastric esterase (Renco™ PGE) and microbial lipase (Palatase® 20,000 L). The fish enzymes were more similar to calf PGE in terms of the total amount and types of fatty acids released over the course of the reaction. Like the pregastric esterase, the fish enzymes released mainly short chain fatty acids. The highest specificity was towards the key dairy product flavour and odour compounds, butanoic and hexanoic acids. The odour intensity of hexanoic acid produced by the salmon lipase, as measured by SPME–GC–MS, was similar to that produced by both Palatase® and PGE. Free fatty acid composition, together with sensory characteristics of lipase-treated creams, demonstrated the potential for flavour enhancement in dairy products using fish lipases.     

Juice components and antioxidant capacity of citrus varieties cultivated in China

Juices from fifteen citrus varieties (seven mandarins, four sweet oranges, one lemon, one grapefruit, and two pummeloes) of China were investigated mainly on quality parameters, total carotenoid, phenolic compounds (total phenolics, flavanone glycosides (FGs), and phenolic acids), and antioxidant capacity (ferric reducing antioxidant power (FRAP) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay). Among the fifteen varieties, Bendizao had the highest content of total carotenoid (10.02 mg/L), Satsuma had the highest content of narirutin (288.12 mg/L), Yinzaocheng had the highest content of hesperidin (533.64 mg/L), and Huyou had the highest content of naringin (348.53 mg/L), neohesperidin (265.25 mg/L) and total FGs (746.08 mg/L). As for total phenolic acids, Liubencheng had the highest content (72.61 mg/L). Hybrid 439 achieved the highest AA content (631.25 mg/L), and the highest total phenolics (1555.49 mg/L) and the greatest inhibition of DPPH radical (61.62%). Hamlin had the highest ascorbic acid equivalent antioxidant capacity (AEAC: 899.31 mg/L) determined by FRAP assay. Correlation coefficients of AA, total phenolics (gallic acid equivalent), FRAP (AEAC), DPPH (I%), total FGs and total phenolic acids indicated that AA played a major role for the antioxidant capacity of citrus juices, and phenolics also played an important role, which may be mainly ascribed to FGs, whilst phenolic acids seemed to play a minimal role. Furthermore, Huyou and Hybrid 439 were considered two valuable varieties from the view of antioxidant capacity and nutrition.