Tryptophan determination in milk-based ingredients and dried sport supplements by liquid chromatography with fluorescence detection

Sport supplements formulas are driven to a sector of consumers which a restrictive diet. Tryptophan is essential amino acid and its bioavailability should be assessed from these commercial products. A robust and fast HPLC procedure is applied to determine total tryptophan content from dairy-ingredients, mostly whey-based ingredients, and commercial dried-sport supplements, mostly whey-enriched sport supplements. The nutritional quality of the protein used in the formulation could be extrapolated to the expected tryptophan content by using a regression curve built from milk-based ingredients. Samples that not conform the correlation are suspected from inadequate industrial practices, such as over-processing, and/or the use of heat-damage ingredients.     

Effect of carbohydrate DE on blocked lysine and furosine in a liquid nutritional product

A controlled, quantitative study of Maillard browning vs. dextrose equivalents (DE) was performed on a liquid nutritional product. The early stage Maillard markers furosine and available lysine were determined in retort-sterilised, pilot scale batches formulated with carbohydrate systems with DE variations of 2, 4, 10, and 20. Both markers varied proportionately with DE; every DE increase of 2 units resulted in the blockage (glycation) of an additional 1% of total lysine. When DE 20 maltodextrin was replaced with an 80/20 blend of DE 5 maltodextrin and sucrose (blend DE = 4), lysine blockage decreased by 831 mg/100 g protein, which was 8.25% of the total lysine, and the mole equivalent of 1.75 g of fructoselysine. The quantitative browning/DE relationships enable reliable projections of the nutritional benefits which may be attained through the use of low-DE maltodextrins.     

Presence of furosine in honeys

Nineteen commercial samples (with a shelf‐life of 2 years) and two artisanal samples (freshly collected and stored for 1 year respectively) of Spanish honeys were analysed for pH, protein content and furosine content. Most of the samples had pH values and protein contents within the limits reported in the literature. The presence of furosine was confirmed by comparison of its retention time with that of a furosine standard and by HPLC–MS. The level of furosine in the samples studied ranged from 4.32 to 13.62 g kg^?1 protein. The lowest furosine value was observed in the freshly collected artisanal sample. Heat treatment under severe conditions (90 °C for up to 135 min) increased the furosine content from 4.43 to 14.38 g kg^?1 protein. The results show that furosine seems to be a promising indicator to detect overheating during honey manufacture. © 2001 Society of Chemical Industry     

“Assessing the Maillard reaction development during the toasting process of common flours employed by the cereal products industry”

The present paper aimed to study the development of the Maillard reaction during the drying–toasting step of different flours usually employed for the formulation of cereal-based products. The results state the idea that a great part of hydroxymethylfurfural (HMF) and furfural found in cereal-based products are supplied by the rest of the ingredients composing these foods and not from the toasting of the flours employed. Moreover, a high furfural generation was associated to the fibre-enrichment of whole wheat flour. Glucosylisomaltol (GIM) measurement could be established as a useful indicator for controlling the manufacture conditions of cereal-based products, if significant amounts of maltose are present. Furosine determination is suitable for flours with either low or high reactivity due to its inherent sensibility to thermal treatment but, in extremely reactive flours like soybean, HMF shows better application. Finally, the ΔE parameter resulted in a reliable measurement of the visible colour production for the toasting step of the flours studied.     

Nutritional quality evaluation of commercial protein supplements

Protein supplements have received increasing attention by consumers over the last few decades. However, hundreds of them have recently exhibited irregularities including lower quantities of proteins than disclosed values. This study aimed to evaluate the nutritional quality of six commercial protein supplement powders (calcium caseinate, milk protein concentrate, egg white, pea protein isolate, whey protein concentrate and soy protein isolate). The chemical composition, amino acid content and in vitro digestibility were examined. Thus, calculate the amino acid scores corrected for amino acid and protein digestibility. In vitro digestion was also conducted and protein hydrolysis was monitored by SDS-page. Calcium caseinate powder and whey protein concentrate were only composed of proteinogenic amino acids and exhibited the highest essential amino acid content. As regards in vitro digestibility, these two supplements perfectly meet the quality expectations of the Food and Agricultural Organization (FAO). Conversely, the other four supplements exhibited a lower quality than the FAO reference protein. This was due to low digestibility (for egg white and milk concentrate) and/or lack of a specific essential amino acid (for milk concentrate and pea isolate).     

液相色谱法测定核桃乳中糠氨酸含量

目的建立液相色谱法测定核桃乳中糠氨酸含量的检测方法。方法样品经酸水解、乙酸铵缓冲溶液定容后,经反相C18色谱柱分离,以甲醇/三氟乙酸溶液为流动相,流速为1.0mL/min,梯度洗脱,在紫外检测器波长为280 nm下检测。结果糠氨酸浓度在2～50μg/L的范围内线性关系良好,相关系数均大于0.999。糠氨酸在2.00、5.00和10.00mg/100g蛋白质添加水平的回收率为88.82%～91.95%,相对标准偏差(relative standard deviation, RSD)小于3.55%(n=6),方法检出限为1.0 mg/100 g蛋白质。结论该方法操作过程简单、方法准确、可靠、重现性好、回收率较高,适合于核桃乳中糠氨酸含量的分析检测。     

Detection of selected stimulants as contaminants in solid nutritional supplements by liquid chromatography–mass spectrometry

Nutritional supplements are frequently used by athletes and can contain substances banned by the World Anti Doping Agency (WADA). The aim of this study was to develop a screening method for the detection of selected stimulants in solid nutritional supplements. Analysis of the samples was performed on an LCQ-Deca^® instrument after an acidic wash with n-pentane and an alkaline liquid/liquid extraction with diethylether. The mass spectrometer was operated in full scan MS² using positive ionisation. Detection limits (LODs) were equal or below 50 ng/g for all compounds except strychnine (100 ng/g). The suitability of the method for routine application was illustrated by the analysis of two suspicious samples.     

Development of the Maillard reaction in foods cooked by different techniques. Intake of Maillard-derived compounds

Specific and non-specific Maillard reaction (MR) indices such as CIELab colour, browning measurement, furosine, hydroxymethylfurfural (HMF) and furfural, as well as the nutrient content, were analysed for commonly consumed dishes, to test the effects of different culinary treatment on dishes composed of the same ingredients. In addition, the consumption of early MR products (MRP), Amadori compounds, HMF and furfural from a normal serving of these dishes was calculated. As expected, recipes including frying, apart from their particular composition, led to significantly higher values of furosine and HMF, ranging from 4.40 to 175 and from 0.30 to 22.7 mg/kg, respectively; consequently they provided the highest levels of Amadori compounds and HMF intake (0.42–26.8 and 0.02–2.38 mg/serving, respectively). Even so, MRP intake/serving was not very high in comparison with levels reported in the bibliography on some individual foods typically studied in terms of MR development, suggesting that the culinary treatments used do not make a great contribution to the daily MRP consumption.     

2017~2018年铜川市运动员食用营养品有效成分分析与评价

目的 了解铜川市2017~2018年运动员食用营养品的功效成分状况, 为运动营养品的功效分析评价和有效的监督管理提供科学依据。方法 于2017~2018年, 采集铜川市8类运动营养食品, 按照国家标准及实验室方法进行功效成分含量的测定, 测定肌酸、蛋白质、番茄红素、牛磺酸等指标, 分析检测结果, 评价铜川市运动员食用营养品的功效成分状况。结果 2017~2018年铜川市共采集40份运动营养品样本, 合格样本28份, 不合格样本12份, 合格率为70%。结论 铜川市2017~2018年运动营养品存在较小程度的隐患, 但有必要针对运动营养品中营养标签标识以及功效成分检测标准加强监督和管理。     

抗运动性疲劳营养补剂的研制

在体育训练和比赛中,运动员不论是在力量、速度、耐力和灵巧等方面都体现了强度大、难度高的特点,精神紧张,体力大量消耗,机体的各个系统都会发生不同的变化和反应,运动时体内激素分泌增加,物质代谢加强,能源物质被大量消耗,酸性代谢产物积聚加快,导致机体内环境发生一系列的变动。特别是在大运动量训练和激烈的比赛中,疲劳是不可避免的。这时机体对营养素的需求量必然发生某些改变。为了适应大运动量和高强度的专业化训练,仅靠平衡膳食是无法满足专业训练所消耗的大量能源物质,必须使用功能性的运动营养补剂来帮助运动员提高耐久力以及恢复体力和运动能力,以帮助运动员承受更大的训练压力和适应更大的额外训练应激,此外,运动营养补剂还可以帮助运动员提高自身内源性物质的合成水平。     

热反应肉味香精质量与价格关系的评价方法

提出一种评价热反应肉味香精(Maillardreactionmeatflavoring)质量与价格关系的方法,利用该方法能比较准确的用数字化的方式表达热反应肉味香精质量与价格之间的关系。     

Protein lactosylation in UHT milk during storage measured by Liquid Chromatography–Mass Spectrometry and quantification of furosine

The initial stage of the Maillard reaction, protein lactosylation, occurs during heat treatment of milk and continues during subsequent storage. We compared the initial lactosylation as well as the rate of lactosylation of milk proteins during storage in UHT milk subjected to direct or indirect heat treatment using liquid chromatography (LC) coupled with electrospray injection mass spectrometry (ESI‐MS). Furosine content was used as an overall marker to allow for a quantitative correlation of lactosylation measured by LC‐ESI‐MS in the UHT milks. Protein lactosylation increased during the storage period of 6 months at 20 °C. Both the initial extent and the rate of lactosylation positively correlated with the number of lysine residues in the different proteins. An exponential or linear correlation with furosine concentration could be established for major and minor lactosylated proteins, respectively.     

A new method to estimate the heat treatment of milk and milk-like systems

A new UV–Vis absorbance spectrum method was proposed to evaluate the heat treatment of milk and milk-like systems. The method was based on the immediate UV absorbance development when heating amino-sugar mixtures, and validated by correlating the absorbance values of milk-like systems, processed at various temperatures and holding times, with furosine content determined using standardized HPLC analysis. The UV method correlated well with the furosine method under mild heating conditions with R ²   =   0.9569 ( P  <   0.001) and 0.9594 ( P  <   0.01) respectively. This method allowed an efficient discrimination of commercial milk heat treatment. The paper offers the possibility to develop an easy, inexpensive and sensitive way to control the milk protein quality.     

Chemical,technological, and nutritional characteristics of two lines of “farro” (Triticum turgidum ssp. dicoccum)

In recent years, the renewed interest for foods with a natural image has increased the demand for dry pasta produced from “hulled” wheat such as the Triticum turgidum ssp. dicoccum, also known as “farro”. In order to contribute to the general knowledge, two lines of farro were considered in this study. To have a comparison, an old cultivar of Triticum turgidum ssp. durum (Senatore Cappelli) in addition to a commercial semolina were also examined. All semolina samples were used to produce pasta samples. Results showed some differences among pasta samples that seem to be due not to the presence of specific protein subunits but especially to the quantitative ratio between the different subunits. Results also reconfirmed the role played by the drying technology that is able to affect the sensory characteristics of pasta products.     

运动类营养补充剂对运动能力影响的研究进展

精心设计的饮食有助于改善身体机能并提升运动能力,但是只要存在竞技运动,运动员就希望可以通过摄取运动类营养补充剂来改善其表现,这样的想法催生了数十亿美元的运动类营养补充剂行业.虽然很多公司都宣称他们的产品可以改善运动员的运动能力,但是大多都没有客观的科学证据.鉴于此,本文综述了近年运动类营养补充剂对运动能力影响的科学研究...     

Nutritional quality of legume seeds as affected by some physical treatments, Part 1: Protein quality evaluation

The effect of water soaking, boiling, roasting, microwave cooking, autoclaving, fermentation and micronization on the nutritional quality of cowpea, pea and kidney bean was investigated. Pea seeds showed the highest crude fat, crude fiber and the lowest moisture contents while kidney bean had the lowest crude fat and the highest crude protein and ash contents. Glu and Asp were the main amino acids in all legumes while Cys and Met contents were the lowest. The protein efficiency ratio (PER), protein chemical score (CS) and the essential amino acid index (EAAI) of raw seeds ranged from 2.15 to 2.95, 39.07 to 68.30, and 55.49 to 62.84, respectively. Soaking, boiling, microwave cooking and autoclaving increased the total essential amino acids in all samples. Furthermore, raw and treated samples showed higher Lys content than the reference protein. Autoclaving was the most effective in improving protein quality followed by micronization, microwave cooking and fermentation. In addition, in vitro protein digestibility was improved after soaking, boiling, microwave cooking, autoclaving and fermentation but was reduced after roasting and micronization.     

Evaluation of thermal treatment markers in wheat flour-derived products cooked in conventional and in low-emissivity ovens

Different markers for the assessment of thermal treatment entity of food products were investigated on a model bread prepared from wheat flour. Samples were submitted to different cooking procedures by combining three different times and temperatures, and employing two different ovens: a low-emissivity oven and a conventional one. The cook value index was calculated for each sample to evaluate the entity of the thermal treatment. Furosine, maltose:maltulose ratio, colour indexes (L, a, b) have been evaluated in all samples. Furosine has been quantified by capillary electrophoresis–mass spectrometry, maltose:maltulose ratio was determined by HPAEC-PAD, colour indexes were measured by spectrophotometer method. Values for weight loss during cooking and surface temperature have also been monitored. A statistical analysis showed good correlation between the cook value index and all the parameters evaluated. Low emissivity oven shown higher performances and lower energy consumption than conventional oven.     

美拉德反应对产品风味品质的影响及其衍生危害物研究进展

在食品加工过程中,美拉德反应虽然对提升食品的风味和品质具有重要作用,但也会衍生一些化学危害物。本文综述了美拉德反应对食品风味和色泽等品质的影响,以及美拉德反应产物的抗氧化和抗突变等特性,同时也探讨了美拉德反应产生的丙烯酰胺(acrylamide,AA)、杂环胺(heterocyclic amines,HAs)和晚期糖基化末端终产物(advanced glycation end products,AGEs)等化学危害物的生成机制、分析和抑制方法。由于3类危害物在食品中的含量较低(ng/g~μg/g)且基质非常复杂,因此其检测均需要采用固相萃取等方法进行分离富集,随后可采用超高效液相色谱串联质谱(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)等方法进行定性定量分析。危害物的抑制主要通过采用更加温和的加工方法、调整工艺参数和添加香辛料及酚类等天然抗氧化物质来实现。     

Furosine as a Pasta Quality Marker: Evaluation by an Innovative and Fast Chromatographic Approach

A fast and simple high‐performance liquid chromatography method suitable for determining furosine level in heat‐treated food samples was developed. The analysis of furosine was performed by a novel mixed‐mode column that provides multiple and simultaneous retention mechanisms including cation‐exchange, anion‐exchange, reversed‐phase, or hydrophilic interaction. Each retention mechanism could be independently controlled by setting chromatographic conditions. Adequate retention and selectivity of polar charged furosine were achieved by adjusting mobile phase pH, buffer concentration, organic content, and ionic strength. The optimized method was successfully applied to determinate furosine in durum wheat semolina pasta samples. Furosine level in pasta may be used as a reliable marker of health and nutritional damage occurring during pasta manufacture. Indeed, a low content of furosine is generally related to high nutritional quality of food and application of mild heat treatments. A wide range of dry pasta samples, collected from both supermarkets (large‐scale retail trade) and shops selling local products, were analyzed. Variable amounts of furosine, ranging from 107 to 506 mg/100 g of protein, were found in pasta samples. The proposed method allows to discriminate products submitted to different time–temperature conditions during the drying process. At the same time, it may be used to highlight potential label fraud.     

Combined use of HMF and furosine to assess fresh honey quality

BACKGROUND: The quality of honey can be affected by practices such as adulteration, inadequate storage or the application of severe heat treatments. Because hydroxymehylfurfural (HMF) is an indicator of honey freshness and furosine (ε‐2‐furoylmethyl lysine) has proved to be a useful chemical indicator of the progress of the Maillard reaction in foods, the aim of this work was to assess their usefulness as indicators of fresh honey quality. The effect of heat treatment, storage and adulteration with different types of syrups on HMF and furosine content has been studied. RESULTS: In fresh honey, HMF and furosine values ranged from 0.9 to 14.6 mg kg^?1 of product and from 3.06 to 12.06 g kg^?1 of protein, respectively. Heating of honey samples with different pH (3.76 and 5.14) produced slight increases in HMF content and negligible changes were detected in furosine values. The storage of fresh honey for 2 years caused a high increase in the HMF level, reaching values above EU limits. However, furosine showed a different behavior depending on the type of honey sample. Adulteration assays using different syrups produced an increase in HMF and a decrease of furosine values by dilution effect. HMF content of adulterated honey samples with syrup of known origin did not exceed EU limits. CONCLUSION: These results show the influence of long periods of storage or adulteration, using different percentages of corn or invert sugar syrups, on HMF and furosine content of fresh honey. This seems to indicate that the combination of HMF and furosine may be useful for evaluating the quality of fresh honey. Copyright © 2009 Society of Chemical Industry