Occurrence of bound 3-monochloropropan-1,2-diol content in commonly consumed foods in Hong Kong analysed by enzymatic hydrolysis and GC-MS detection

The aim of this study was to determine the level of bound 3-monochloropropan-1,2-diol in foodstuffs commonly consumed in Hong Kong, China, by an enzymatic hydrolysis indirect method which proved to be free from interferences. A total of 290 samples were picked up randomly from the local market and analysed. About 73% of these samples were found to contain detectable amounts of bound 3-MCPD. Amongst the 73 food items, bound 3-MCPD was not detected in 13 food items, including extra virgin olive oil, beef ball/salami, beef flank, ham/Chinese ham, nuts, seeds, soy sauce, oyster sauce, butter, yoghurt, cream, cheese and milk. For those found to contain detectable bound 3-MCPD, the content ranged up to 2500 µg kg^?1. The highest mean bound 3-MCPD content among the 14 food groups was in biscuits (440 [50–860] µg kg^?1), followed by fats and oils (390 [n.d.–2500] µg kg^?1), snacks (270 [9–1000] µg kg^?1), and Chinese pastry (270 [n.d.–1200] µg kg^?1). Among the samples, the highest bound 3-MCPD content was in a grape seed oil (2500 µg kg^?1), followed by a walnut flaky pastry (1200 µg kg^?1) and a grilled corn (1000 µg kg^?1). Basically, the results of this study agreed well with other published results in peer-reviewed journals, except for cheese, cream, ham, nuts and seeds.     

Nitrate and nitrite levels in commonly consumed vegetables in Hong Kong

Levels of nitrate and nitrite in 73 different vegetables, a total of 708 individual samples grouped into leafy, legumes, root and tuber, and fruiting vegetables, which are traded mainly in Hong Kong, were measured. Where available, five samples of each vegetable type were purchased from different commercial outlets during the winter of 2008 and summer of 2009. Levels of nitrate and nitrite were determined by ion chromatography and flow injection analysis, respectively. Nitrate and nitrite levels of all samples ranged <4–6300 and <0.8–9.0 mg?kg^?1, respectively. Nitrate concentrations for the different groups, in descending order, were leafy?>?root and tuber?>?fruiting and legume vegetables. More than 80% of vegetables had mean nitrate concentrations less than 2000?mg?kg^?1, but mean nitrate concentrations of three types of leafy vegetables, namely Chinese spinach, Shanghai cabbage and Chinese white cabbage, were >3500?mg?kg^?1. On the other hand, nitrite concentrations were generally low –?<1?mg?kg^?1 on average. Nitrate in vegetables (i.e. Chinese flowering cabbage, Chinese spinach and celery) can be reduced significantly (12–31%) after blanching for 1–3?min, but not after soaking.     

Investigation of pyrrolizidine alkaloids including their respective N-oxides in selected food products available in Hong Kong by liquid chromatography electrospray ionisation mass spectrometry

ABSTRACT

This study determined the levels of pyrrolizidine alkaloids (PAs), including their respective N-oxides, in foodstuffs available in Hong Kong by liquid chromatography-electrospray ionisation tandem mass spectrometry. A total of 234 samples (48 food items) were collected randomly from a local market and analysed. About 50% of samples were found to contain detectable amount of PAs. Amongst the 48 food items, PAs were not detected in 11 food items, including barley flour, beef, cattle liver, pork, pig liver, chicken meat, chicken liver, milk, non-fermented tea, Melissa tea and linden tea. For those found to contain detectable PAs, the summed PA content ranged up to 11,000 µg kg^?1. The highest sum of PA content among the 37 food items calculated with lower bound was cumin seed, then followed by oregano, tarragon and herbs de Provence with ranges of 2.5–11,000, 1.5–5100, 8.0–3300 and 18–1300 µg kg^?1 respectively. Among the samples, the highest sum of PA content was detected in a cumin seed sample (11,000 µg kg^?1), followed by an oregano (5100 µg kg^?1), a tarragon (3300 µg kg^?1) and a herbs de Provence (1300 µg kg^?1). In general, the results of this study agreed well with other published results in peer-reviewed journals, except that the total PAs in honey and specific tea infusion in this study were comparatively lower.     

Dietary exposure of Hong Kong adults to fatty acid esters of 3-monochloropropane-1,2-diol

A total of 290 individual food samples were collected in Hong Kong, China, for 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters analysis. Most samples were processed food and in ready-to-eat form. The results show that the levels of 3-MCPD fatty acid esters were high in biscuits, fats and oils, snacks and Chinese pastry with mean bound 3-MCPD levels of 440, 390, 270 and 270 μg kg^?1, respectively. The dietary exposures to bound 3-MCPD of average and high adult consumers were estimated to be 0.20 and 0.53 μg kg bw^?1 day^?1, respectively. The primary toxicological concern of 3-MCPD fatty acid esters is its potential to release 3-MCPD in vivo during digestion in the gastrointestinal tract. 3-MCPD would affect the kidney, the central nervous system and the male reproductive system of rats. Assuming that 100% of the 3-MCPD was released from 3-MCPD fatty acid esters by hydrolysis in the digestive system, the dietary exposures to 3-MCPD for average and high adult consumers were only 10% and 26% of the provisional maximum tolerable daily intake (PMTDI) of 3-MCPD established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) (2 μg kg bw^?1 day^?1), respectively. The results suggest that both average and high adult consumers are unlikely to experience major toxicological effects of 3-MCPD.     

从香港盛会看丝绸收藏和研究的国际化趋势

中国古代丝绸文物展和中国古代丝绸学术讨论会首次在香港举行。这次盛会汇集了世界各地丝绸史研究专家，从中了解到，对中国古代丝绸的收藏已受到国外收藏家的重视，同时对中国丝绸史的研究近年来也方兴未艾，呈现出一种国际化的趋势。     

The effect of food stuffs commonly consumed in egypt on iron absorption and utilisation

The absorption and utilisation of iron in rats fed stewed beans, lentils, fenugreek and wheat bread were measured and compared with that of rats fed on casein. The results showed that ⁵⁹Fe absorption and utilisation were better on the casein diet. Fenugreek promoted absorption and utilisation of iron relative to other food commodities. Stewed beans inhibited both absorption and utilisation of iron. Lentils, in spite of retarding iron absorption, assisted the utilisation. Amino acids and phytate phosphorus content of these ingredients are thought to play a part.     

Dietary exposure of Hong Kong secondary school students to total mercury and methylmercury from fish intake

Fish is the main source of dietary exposure to methylmercury (MeHg), which is a public health concern owing to its potential neurotoxicity. To evaluate the public health risk, this study estimated the total mercury (tHg) and MeHg exposure from fish intake in Hong Kong secondary school students. Median tHg and MeHg concentrations of 280 samples purchased from different commercial outlets (covering 89 species of whole fish and three types of canned tuna), together with the local food consumption data of secondary school students obtained by semi-quantitative food frequency questionnaire in 2000, were used to estimate dietary exposure from fish intake for the average and high consumer (95th percentile exposure). For tHg, the median concentration was 63 µg kg^–1 (range 3–1370 µg kg^–1) and estimated exposures ranged 0.5–0.6 µg kg^–1 body weight (bw) week^–1 for an average consumer and 1.6–1.9 µg kg^–1 bw week^–1 for a high consumer. For MeHg, median concentration was 48 µg kg^–1 (range 3–1010 µg kg^–1) and estimated dietary exposures were 0.4–0.5 µg kg^–1 bw week^–1 for an average consumer and 1.2–1.4 µg kg^–1 bw week^–1 for a high consumer. These values are below the respective provisional tolerable weekly intake (PTWI) established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA). The health risk is greater for high consumers since MeHg exposures may approach or exceed the PTWI when other dietary sources are taken into account.     

不同烹调方式对植物源食物营养成分及抗氧化活性的影响

植物源食物是人类饮食中至关重要的组成部分,提供人体所必需的多种营养成分,特别是多数植物源食物具有强抗氧化活性,可有效预防人体氧化损伤所引起的衰老和疾病。植物源食物的基本营养成分及抗氧化活性在加热烹调过程中会发生变化。本文旨在综述几种烹调方式对植物源食物营养成分组成和抗氧化活性的影响。     

Dietary exposure to chloropropanols of secondary school students in Hong Kong

This paper reports levels of 3-monochloropropan-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) in a wide range of food items and estimates their dietary exposure for secondary school students in Hong Kong. Dietary exposure to chloropropanols was estimated using local food consumption data obtained from secondary school students in 2000 and the concentrations of 3-MCPD and 1,3-DCP in food samples taken from the local market. The dietary exposure to 3-MCPD for an average secondary school student consumer was estimated to be 0.063–0.150 µg kg^?1 body weight (bw) day^?1, whilst that for the high consumer was 0.152–0.300 µg kg^?1 bw day^?1. Both estimates fell below the provisional maximum tolerable daily intake of 2 µg kg^?1 bw established by the Joint Expert Committee on Food Additives (JECFA) and amounted to less than 20% of this safety reference value. The dietary exposure to 1,3-DCP for an average secondary school student consumer was estimated to be 0.003–0.019 µg kg^?1 bw day^?1, whilst that for the high consumer was 0.009–0.040 µg kg^?1 bw day^?1. The resulting margins of exposures were of low concern for human health. It could be concluded that both the average and high secondary school student consumers were unlikely to experience major toxicological effects of 3-MCPD and 1,3-DCP.     

Iodine content in bread,milk and the retention of inherent iodine in commonly used Indian recipes

Iodine deficiency disorders (IDD) is still a major public health problem and iodized salt remains the most effective means to control IDD in India. Few reports indicate that vegans have inadequate iodine intake while at the same time concerns are being raised on the implementation of universal salt iodization in the country. Therefore, we investigated the iodine content in bread, milk and commonly used Indian recipes prepared without iodized salt and the retention of inherent iodine therein. Results showed considerable iodine content in bread (25 μg/100 g) and milk (303 μg/L) as a positive fallout of universal salt iodization. Iodine content in 38 vegetarian recipes prepared without iodized salt was very low (2.9 ± 2.4 μg/100 g). Retention of inherent iodine (65.6 ± 15.4%) and iodine from iodized salt (76.7 ± 10.3%) in the same recipes was comparable. Thus, universal salt iodization programme remains the single most important source of dietary iodine for the Indian population.     

Iodine content of cooked and processed fish in Turkey

This study evaluates the effects of different cooking (grilling, frying and steaming) and processing (smoking, salting, marinating and drying) methods on iodine contents of valuable marine and freshwater fish species commonly consumed in Turkey. The highest mean iodine content of cooked fish was determined to be 3.760 mg kg^?1, 2.788 mg kg^?1, 5.831 mg kg^?1 and 6.161 mg kg^?1 in grilled anchovy, horse mackerel, Atlantic Bonito and whiting, 0.914 mg kg^?1, 1.452 mg kg^?1, 3.106 mg kg^?1 in steamed bluefish, red mullet. The highest mean iodine content of processed fish was determined to be 2.149 mg kg^?1 in smoked mackerel, 0.701 mg kg^?1 in salted Bonito, 1.128 mg kg^?1 in dried horse mackerel and 7.283 mg kg^?1 in marinated anchovy. This iodine values are also above the Upper Tolerable Nutrient Level of 100–150 μg day^?1 iodine.     

Tannin content of foods commonly consumed in India and its influence on ionisable iron

The tannin content of a number of foods and diets commonly consumed in India has been determined. Most of the tannin in legumes resides in the seed-coat. Decortication of seeds reduced tannin to a low level with a significant increase in ionisable iron. Germination of the legumes also resulted in a decrease in tannin and an increase in ionisable iron. Diets consumed in different parts of the country had tannin contents ranging from 1.5 to 2.5 g. Much of this appeared to be contributed by spices. A high level of tannin in these foods is associated with low ionisable iron. It is suggested that besides phytates, tannin may be an important factor responsible for the low absorption of iron from habitual diets in India.     

Dietary exposure to mycotoxins of the Hong Kong adult population from a Total Diet Study

Dietary exposure of Hong Kong adults to mycotoxins and their metabolites including aflatoxins (AFs), ochratoxin A (OTA), fumonisins (FNs), deoxynivalenol (DON), acetyldeoxynivalenols (AcDONs) and zearalenone (ZEA) was estimated using the Total Diet Study (TDS) approach to assess the associated health risk to the local people. Sixty commonly consumed food items, collected in four seasons, were sampled and prepared as consumed. These mycotoxins were primarily found at low levels. The highest mean levels (upper bound) were: AFs, 1.50 µg kg^–1 in legumes, nuts and seed; OTA, 0.22 µg kg^–1 in sugars and confectionery; FNs, 9.76 µg kg^–1 in cereals and their products; DON and AcDONs, 33.1 µg kg^–1 in cereals and their products; and ZEA, 53.8 µg kg^–1 in fats and oils. The estimated dietary exposures of Hong Kong adults to the mycotoxins analysed were well below the respective health-based guidance values, where available. For AFs, the upper-bound exposure for high consumers is 0.0049 µg kg bw^–1 day^–1, which was estimated to contribute to about 7.7 (< 1%) of liver cancer cases when compared with 1222 liver cancer cases per year in Hong Kong. The percentage contributions of the estimated 95th percentile dietary exposures (lower and upper bound) to the health-based guidance values of individual mycotoxins were: ochratoxin A, 3.6–9.2%; fumonisins, 0.04–8.5%; deoxynivalenol and acetyldeoxynivalenols, 21.7–28.2%; and zearalenone 3.3–34.5%. The findings indicate that dietary exposures to all the mycotoxins analysed in this study were unlikely to pose an unacceptable health risk to the Hong Kong population.     

Effect of different cooking method on vitamin E and K content and true retention of legumes and vegetables commonly consumed in Korea

Food Science and Biotechnology - This study investigated the effect of cooking method on the content and true retention of vitamin E and K in legumes and vegetables, which are commonly consumed in...     

Phenolic acid content of fruits commonly consumed and locally produced in Scotland

Despite fruit, vegetables and many processed products counting towards achieving the recommended five-a-day strategy, it is inevitable that produce choice will affect the benefits delivered. Fruits locally produced and commonly consumed in Scotland were compared for their phenolic acid content and form. The phenolic acid composition was highly variable, but the locally produced fruits were significantly (p < 0.001) higher in total concentration (1.61–4.89 g/kg compared to 0.06–0.22 g/kg). The majority of the phenolic acids were conjugated to other plant components, suggesting that any health benefits derived from these compounds are likely to be after they are released/metabolised by the colonic microbiota. Although the potential protective effects of the individual compounds will not be ascertained until the exact role of these compounds in disease prevention has been clarified, it is clear that the total amount of phenolic acids in the diet will vary enormously depending on the types of fruits consumed.     

Changes in l-carnitine content of fish and meat during domestic cooking

Human adults store around 20g of l-carnitine. In the human body, l-carnitine is not metabolized but excreted through the kidney. Lost l-carnitine has to be replenished either by a biosynthetic mechanism or by the consumption of foods containing l-carnitine. Today, there is no "official" recommended daily allowance for l-carnitine but the daily need for l-carnitine intake has been estimated in the wide range of 2-12μmol/day/kg body weight for an adult human. In this study we evaluated the effect of freezing and of different cooking methods on the l-carnitine content of red meat and fish. l-carnitine was abundantly present in all beef products analyzed. The amounts in the various cuts were similar and our data showed that freezing or cooking did not modify l-carnitine content. Salmon contained about 12 times less l-carnitine than beef but except in smoked salmon, cooking or freezing did not alter l-carnitine content. This study confirms the important role that meet products play for providing adequate amount of l-carnitine to the human body.     

The sulphydryl plus disulphide content in the proteins of durum wheat and its relationship with the cooking quality of pasta

Semolina samples were obtained from several durum wheat cultivars. The cooking quality of the spaghetti prepared from the semolina showed both inter and intravarietal differences. Proteins from semolina were extracted sequentially and both the reactive and total ? SH plus S? S content of the protein extracts determined amperometrically. The albumin-globulin fractions contained the highest amounts of both reactive and total ? SH plus S? S groups. The total ? SH plus S? S content was higher in the gliadins than in the glutenins but the latter contained higher amounts of reactive ? SH plus S? S groups. A highly significant correlation was found between the total amount of ? SH plus S? S content of the glutenins and the cooking quality of the samples (r=0.835): This might be a functional relation.     

Effect of food processing on the resistant starch content of cereals and cereal products – a review

Depending on the conditions, processing of cereal grains may cause an increase or a decrease in the resistant starch (RS) content. This review discusses the impact of some of the processing techniques (cooking, tempering and extrusion) on the RS contents of cereals and cereal products. In addition to processing, the review briefly summarises the effects of lipids, dietary fibre and sugars, which may be present within the food matrix, on starch digestibility. The review also provides definitions for the four types of RS (RS type 1, 2, 3 and 4) and brief information about the beneficial effects of RS on human health.     

食品中“塑化剂”检测技术与应对策略

食品安全事件时有发生,在2011年台湾地区出现"起云剂"(即塑化剂)事件后,前不久媒体又曝出我国某著名白酒品牌产品中"塑化剂"超标事件,从而引发了人们对"塑化剂"进一步的关注及思考。文中对塑化剂的定义及种类、食品中可能含有的主要塑化剂种类、食品中塑化剂的检测方法、邻苯二甲酸酯类物质在食品包装材料中迁移的研究以及引起食品塑化剂超标的原因及对策做了系统介绍,为相关科研人员的进一步研究提供参考。     

Short communication: Iodine content in bovine milk is lowly heritable and shows limited genetic variation

Milk and dairy products are considered important sources of iodine in several countries. Despite this, there is a paucity of studies that have investigated sources of variation of milk iodine, especially on a large scale. So far, it is not clear if milk iodine content could be increased through breeding in dairy cattle. Recently, a mid-infrared spectroscopy prediction model has been developed for an indirect quantification of iodine content in cow milk, as it is a faster and less expensive method that allows the prediction at population level. The model has coefficient of determination and ratio of performance to deviation in external validation of 0.57 and 1.44, respectively, and it was used in the present study to predict the iodine content from historical milk spectral data to investigate phenotypic and genetic aspects in the Italian Holstein cattle. Based on the accuracy of the model, the prediction was interpreted as proxy for the real milk iodine concentration (IOD_P). The data set comprised 33,776 test-day records with IOD_P from 4,072 cows. Data of IOD_P were transformed through natural logarithm to achieve a normal distribution. The effect of parity, lactation stage, and month of sampling were investigated, and genetic parameters were estimated using a test-day repeatability animal model. Milk IOD_P decreased with parities and was the lowest in early lactation. Heritability of IOD_P was low (0.025) and it was positively genetically correlated with milk yield and negatively with fat content. Results suggested that it would be challenging to directly improve this trait through breeding strategies in dairy cattle, because IOD_P is mainly affected by temporary environmental factors and thus, cannot be easily improved through genetics. Although preliminary, findings of this study suggest that it would be more convenient to develop feeding and management strategies to drive milk iodine level than to put efforts and resources into breeding strategies. Further studies should validate IOD_P as an indicator trait of milk iodine content by improving reference data and estimating genetic correlation between predicted and measured values.