Sensory characteristics and iron dialyzability of gluten-free bread fortified with iron

The objectives of the present study were (a) to produce gluten-free bread, fortified with iron (GFB-Fe), using selected iron compounds (ferric pyrophosphate, ferric pyrophosphate with emulsifiers, NaFeEDTA, electrolytic iron, ferrous gluconate, ferrous lactate and ferrous sulphate) (b) to test sensory characteristics of the GFB-Fe (feel-mouth texture, crumb colour, aroma and taste) (c) to compare iron dialyzability of various iron compounds in GFB-Fe. The most acceptable products were those fortified with ferric pyrophosphate with emulsifiers and ferric pyrophosphate. Ferrous dialyzable iron (ferrous iron with molecular weight lower than 8000 Da, an index for prediction of iron bioavailability) was measured under simulated gastrointestinal conditions. Ferrous dialyzable iron in GFB-Fe fortified with ferric pyrophosphate with emulsifiers, NaFeEDTA, ferrous bis-glycinate, ferrous gluconate or ferrous sulphate was higher than that in GFB-Fe fortified with electrolytic iron, ferrous lactate or ferric pyrophosphate (P < 0.05). These results are promising for the development of GFB-Fe products in the future.     

Determination of folate in some cereals and commercial cereal-grain products consumed in Poland using trienzyme extraction and high-performance liquid chromatography methods

A trienzyme treatment (rat plasma conjugase, -amylase, protease) followed by affinity chromatography (with folate-binding protein from bovine milk) and reversed-phase high-performance liquid chromatography with UV and fluorescence detections was performed for quantification of different folate derivatives in some commercial cereal-grain products and cereals cultivated in Poland. The method described allowed good separation of the main folate vitamins. Of the commercial cereal-grain products analyzed, buckwheat groats (30 g/100 g) had the highest content of total folate, followed by rye flour (29 g/100 g), barley groats (21 g/100 g) and wheat flours (19–20 g/100 g). Two of the ready-to eat breakfast products were found to be fortified with folic acid with the level slightly exceeding the label declaration. The total folate content of whole-grain wheat flours was more than half as much as in white flours (33–40 g/100 g), and the highest folate content was found in rye whole grains (123–135 g/100 g). 5-Formyltetrahydrofolate was the predominating folate form in the cereal products analyzed, above all in rye flour.     

Folate content in foods commonly consumed in Egypt

The folate content in some Egyptian foods was determined using RP-HPLC-FL. Trienzyme treatment was used for legumes, dienzyme treatment for cereals and starchy vegetables, and monoenzyme treatment for vegetables and fruits. The highest folate content (633 μg/100 g) was found in dried Jew’s mellow due to low water content, followed by legumes (e.g. 150 μg/100 g for chick peas) and leafy vegetables (100 μg/100 g). For other foods, folate content ranged from 10–90 μg/100 g. In all foods, the predominant folate form was 5-CH₃–H₄folate, except for dried Jew’s mellow, which contained more than 80% 10-HCO–PteGlu. Using folate data from our own analyses and food tables and food consumption data, the dietary folate intake per capita in Egypt was estimated. However, representative and validated food composition data for folate in Egyptian foods are needed for estimating and evaluating the adequacy of the population’s folate intake.     

菊粉型果聚糖在无麸质产品中应用的研究进展

由于谷蛋白相关疾病与含谷蛋白食物的摄入有关,无麸质产品在食品工业中受到广泛关注,菊粉型果聚糖已成为无麸质产品的有益成分.本文介绍了菊粉型果聚糖在无麸质产品中应用的技术背景,阐述了菊粉型果聚糖的物理化学特性及其作为组成部分对无麸质产品的技术性能和感官质量的影响,分析了菊粉型果聚糖添加到无麸质产品后与其他成分和添加剂之间的...     

Optimization of microbiological assay of folic acid and determination of folate content in spinach

The microbiological method for the determination of folate in plant foods uses the growth response of folate‐dependent Lactobacillus rhamnosus in extracts that have been enzymatically treated to release the bound vitamin. However, the use of cryoprotected cultures is hampered by low recovery of the microorganism after extended frozen storage times. In this study, growth of L. rhamnosus was enhanced using a microaerophilic enrichment procedure and optimal pH conditions and enzyme reaction times were determined for the release of bound folate in spinach. Optimum pH values for the release of bound folate in spinach samples treated with α‐amylase or protease were 3.0 and 4.0, respectively. Although treatment with α‐amylase had no significant (P > 0.05) effect on measured folate, addition of protease at pH 4.0 significantly (P 0.05) increased the release of folate at an optimum incubation time of 8 h. Therefore, a dual‐enzyme treatment (protease and conjugase) is sufficient to determine folate content in spinach.     

感官评价及其在谷物制品中的应用现状

简要介绍了感官评价的定义、应用及其在食品工业中的重要性。重点阐述了感官评价在部分谷物制品评价中的应用,包括大米食味和小麦粉制品食用品质的感官评价。详细描述了大米、面条、面包、馒头品质的感官评价方法、相关研究及存在的问题等。     

Increasing the folate content in Egyptian baladi bread using germinated wheat flour

The main objective of this study was to increase the folate content in Egyptian baladi bread using germinated wheat flour (GWF). The effect of germination temperature and drying conditions on the folate content of wheat grains was studied. Wheat flour was substituted with unsieved and sieved GWF at different levels and the effects on folate content and the rheological properties of dough were determined. Germination of wheat grains resulted in a 3- to 4-fold higher folate content depending on the germination temperature. Maximum folate content (61 μg/100 g dry matter (DM)) occurred at 30 °C. Drying did not affect folate content in germinated grains. After replacement with GWF, folate content in both flour and bread increased 1.5- to 4-fold depending on the level of replacement. Rheological properties of dough were adversely affected by increasing replacement level (as determined by farinograph). While the folate content in bread was as high as 66 μg/100 g DM at complete replacement of flour with sieved GWF, the bread was dark and layers were not separated. After replacement of half of the flour with sieved GWF (50 g/100 g), the baladi bread was acceptable with respect to colour and layer separation. The folate content in this bread was 50 μg/100 g DM, compared with 30 μg/100 g DM in bread without GWF (0 g/100 g).     

Phytic acid content in milled cereal products and breads

Phytic acid was determined in cereal (brans, flours and milled wheat-products) and breads. The method was based on complexometric titration of residual iron (III) after phytic acid precipitation. The cereal flours showed values ranged between 3–4 mg/g for soft wheats, 9 mg/g for hard wheat and 22 mg/g for whole wheat. Corn, millet and sorghum flours reported a mean of 10 mg/g and oat, rice, rye and barley between 4 and 7 mg/g. Wheat brans had wide ranges (25–58 mg/g). The phytic acid for oat brans was half that of wheat bran (20 mg/g) and higher value (58 mg/g) than that for rice bran. The milling products (semolinas) from hard wheat exhibited 10 mg/g and soft wheat a mean of 23 mg/g. The breads made with single or mixture cereal flours exhibited ranges between 1.5 and 7.5 mg/g. The loss of phytic acid relative to unprocessed flours was between 20% for oat bread and 50% for white bread.     

乳制品中的Maillard反应标示物及其应用

乳制品中的Maillard反应标示物既可作为乳制品热处理程度的指标，还可用于不同热处理乳制品的鉴别。介绍了在评价乳制品热处理程度以及区分不同乳制品中常用的几种Maillard反应标示物。这些标示物包括糠氨酸、乳果糖、糠醛类化合物、荧光化合物等。此外，还介绍了可溶性乳清蛋白、碱性磷酸酶和乳过氧化物酶等热处理标示物，这些标示物与Maillard反应之间具有较好的相关性，也是评价乳制品热处理程度以及区分不同乳制品时常用的指标，可与Maillard反应标示物联合应用。     

Folate content in frozen vegetarian ready meals and folate retention after different reheating methods

Folate content and retention were evaluated in 10 different precooked vegetarian ready meals before and after reheating. Folate was quantified using a validated high-performance liquid chromatography method. The only form of folate found was 5-methyltetrahydrofolate. Folate content in thawed ready meals varied from 23 to 81 μg/portion (400 g) on fresh weight basis. Products served with couscous and potatoes contained more folate than products served with rice. Folate retention during reheating was investigated in the microwave oven (900 W/5.5 min), in a saucepan on stove until the food reached 85 °C, and in oven (225 °C/40 min). The true vitamin retention varied for the three investigated portions as follows: on stove (63-93%), microwaving (55-89%) and in oven (50-92%). Our results indicate that folate content in the ready meals prior to reheating, contributed to 6-27% of the recommended intake (300 or 400 μg folate per day). After reheating folate content was significantly (P<0.05) reduced in some meals but were kept constant in others and folate content was reduced to 3-25% of the recommended value. No clear pattern in folate retention between different heating methods was seen. However, the meals with ingredients suggesting high concentrations of antioxidants were less prone to loose folate when heated since the antioxidants probably protected the folates.     

Nitrogen-to-protein conversion factors for some cereal products in Japan

ABSTRACT:  To evaluate a practical method of determining more accurately conversion factors for calculating the protein contents of foods from the total nitrogen content, 19 cereal products found in Japan were analyzed for total nitrogen, amino acid nitrogen, and amide nitrogen, and then the nitrogen-to-protein conversion factors were calculated. The average conversion factors were 5.75 for rice, 5.81 for wheat, and 5.95 for others. These values, corresponding to the proportion of the amino acid residue to amino acid nitrogen recovered from 20 amino acids, were lower than the currently applied factors to these foods, except for wheat flour and amaranth. The use of this factor for estimating the protein content results in a considerable difference from the estimate based on amino acid residue concentrations, due to the wide variations in amino acid composition and to the presence of a significant level of nonprotein nitrogen. The distribution of the protein nitrogen recovered from the amino acids to total nitrogen averaged 93%. Adjusted conversion factors corresponding to the proportion of the amino acid residue to total nitrogen averaged 5.26 for rice, 5.47 for wheat, and 5.54 for other cereal products. Protein contents estimated using these factors are in good agreement with the contents defined as amino acid residues.     

浙江省主要海产品中铬元素含量分布及风险分析

目的分析浙江省主要海产品中铬(Cr)的含量分布情况,并对其进行风险分析。方法采用电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry, ICP-MS)测定浙江省沿岸海域21种海洋经济种中的Cr元素含量。以样品检测结果为数据基础,分析海产品中Cr元素分布特征;采用单因子污染指数法分析检测结果评价不同海产品中Cr元素的污染程度;同时结合第五次中国总膳食研究调查数据,采用非致癌风险评价方法计算Cr元素的危害商数(target hazardquotients, THQ),并进行食用健康风险评估。结果贝类污染指数(pollution index, Pi)为0.796,属于中度污染;虾类、蟹类和头足类Pi值分别为0.282、0.260和0.352,处于轻度污染水平;鱼类Pi值为0.148,为未受污染水平。5类海产品的危害商数THQ为0.046～0.208,均小于安全基准值1。结论浙江省主要海产品对人体不具有潜在的健康风险。     

乳酸菌发酵在谷物产品中的应用及研究进展

谷物食品是人类能量摄入的主要来源之一,随着人们生活水平的提高,谷物食品的营养价值和食用品质受到了广泛关注。发酵是改善食品性质、功能及营养缺陷的重要方法,也是谷物加工的重要手段。乳酸菌能够利用碳水化合物进行生长代谢,在食品工业中被广泛应用于各种发酵制品,其发酵产生的代谢产物有许多重要的生理功能,包括调节肠道菌群平衡、提高免疫力、抗菌和抗肿瘤等。因此,乳酸菌发酵在谷物食品中的研究与应用,对提升食品品质具有重要意义。本文综述了乳酸菌发酵对谷物营养成分、生物功能和结构、理化性质的影响,总结了乳酸菌发酵谷物产品的优势以及乳酸菌发酵在多种谷物产品中的应用,分析了乳酸菌发酵谷物食品目前研究的不足及可能的发展方向, 拟为乳酸菌发酵在谷物中的研究与开发提供参考。     

Analysis of free amino acids in cereal products

Free amino acids were extracted from cereal products using 50% ethanol to prevent solubilization of polysaccharides and other viscous polymers and to avoid starch gelatinization. The extracts were analyzed by GC after ion-exchange solid phase extraction and chloroformate derivatization using Ez-Faast technology (Phenomenex). Free amino acids in cereal products could be analyzed within 1 h of extraction and determination, with good separation between peaks and repeatable retention times. Relative correction factor for each amino acid was established. The matrix did not affect the results and the method was repeatable for most of the amino acids (coefficient of variation was in the order of 10%). Different fractions and products of wheat, rye, oats and barely were analyzed. The bran contained more free amino acids than did the other analysed fractions of cereals. Fermentation seemed to consume free asparagine and aspartic acid and to use or release other amino acids.     

焙烤类谷物食品糖基化产物的定性、定量评价方法

糖基化产物与心血管疾病、糖尿病等多种慢性病的发生有关,因此对食品中糖基化产物含量的评价尤为重要。研究了不同酶解条件对结合态糖基化产物的释放,并且建立了以色度、吸光度、荧光强度等为考察指标综合评价不同反应途径的糖基化产物含量的体系。结果表明:分别采用E320μg/mL和640μg/mL酶解焙烤类谷类食物,40℃酶解36 h,结合态糖基化产物释放较为充分。谷物早餐中美拉德反应产物含量低于饼干和面包;荧光性晚期糖基化终产物含量大小依次为:饼干(1 890 AU/mg)面包(1 886 AU/mg)谷物早餐(1 678 AU/mg)。另外,早餐谷物中初期(A_(208))、中期糖基化产物(A_(360))显著高于饼干和面包(P0.05),而早餐谷物中期和末期糖基化反应产物(戊糖素、5-HMF和HMF)含量显著低于面包和饼干(P0.05)。     

甘肃省市售杏仁和扁桃仁及其制品中氰化物含量状况调查

目的 调查甘肃省内市场上常见的杏仁和扁桃仁及其制品中氰化物含量,为保障人群的健康和国家制定相关标准提供科学依据。方法 从甘肃省14个地市采集样品323份,采用气相色谱-顶空法测定氰化物含量,用秩和检验分析。结果 不同产品中氰化物含量范围为干果类0.098 0～720 mg/kg,固体饮料类0.015 1～151 mg/kg,液体饮料类0.015 1～7.15 mg/kg,糕点类0.184～5.88 mg/kg,糖果类0.083 2～5.11 mg/kg,腌渍类0.702～17.3 mg/kg;不同品种中氰化物含量范围为苦杏仁及其制品0.015 1～720 mg/kg,甜杏仁及其制品0.015 1～151 mg/kg,扁桃仁及其制品0.098 0～12.0 mg/kg;不同种类中氰化物含量范围为熟(干)甜杏仁0.482～20.9 mg/kg,生(干)甜杏仁1.05～151 mg/kg,鲜甜杏仁2.32～184 mg/kg,熟(干)苦杏仁359～597 mg/kg,生(干)苦杏仁359～720 mg/kg,鲜苦杏仁634～733 mg/kg。结论 氰化物在杏仁及其制品中普遍存在,尤其是鲜苦...     

肉制品中动物源性成分DNA检测方法的研究进展

肉制品主要成分标识的真实性是全球重要的食品安全问题之一,特别是肉制品中动物源性成分的掺假和标识问题已引发全球关注。如何对肉制品中动物源性成分进行鉴定和标识已成为产品真实性鉴定的热点。基于DNA分子稳定性强的优点,DNA检测技术被广泛用于食品安全检测和监测诸多领域,体现出了灵敏度高、特异性强等优势。本文重点从动物源性检测的靶序列DNA选择和DNA分析技术研究2个方面,阐述了肉制品中动物源性成分定性、定量检测技术的研究和应用,并讨论动物源性成分定量分析的可能性,为我国实施动物源性成分量化监管提供思路。     

冲调谷物制品污染菌相的调查分析

目的 了解冲调谷物制品中的微生物污染情况及主要污染菌种类,探讨传统形态学鉴定法、分子生物学鉴定法和基质辅助激光解吸电离飞行时间质谱法（matrix assisted laser desorption ionization time of flight mass spectrometry, MALDI-TOF-MS）鉴定微生物的适用效果。方法 以流通领域抽取的冲调谷物制品为研究对象,采用国家标准方法对其菌落总数和霉菌进行计数,分离纯化不合格产品中的污染菌,以基质辅助激光解吸电离飞行时间质谱（matrix assisted laser desorption ionization time of flight mass spectrometry, MALDI-TOF-MS）结合16S rRNA序列分析方法对污染细菌进行鉴定,以MALDI-TOF-MS方法结合传统形态学鉴定方法对污染霉菌进行鉴定。结果 110批次冲调谷物制品的菌落总数不合格率为3.6%,霉菌计数不合格率为4.5%;分离得到的159株细菌可归于28个种,芽孢杆菌属（Bacillus）细菌为优势菌群,分离频率达到71.7%;分离得到的98株霉菌可划分至25个属,青霉属（Penicillium）和曲霉属（Aspergillus）为优势菌群,分离频率分别为12.4%和7.1%。污染菌中含有克罗诺杆菌（Cronobacter）等条件致病细菌和多种常见产毒真菌,存在一定的食品安全风险。结论 冲调谷物制品的微生物污染情况较为严重,生产企业应重视生产加工过程中的微生物污染问题,相关部门应加强对冲调谷物制品的食品安全监管。MALDI-TOF-MS方法在鉴定细菌时具有较大优势;受限于真菌数据库的不足,其用于食品来源霉菌鉴定的准确率有待提高。     

辣椒制品中花椒油素含量的测定

以两次提取,提取时间分别为3,0.5h,提取溶剂甲醇量分别为70,20mL,采用ZORBAX XDB-C18柱(4.6mm×150mm,5μm)为色谱柱,甲醇-水(体积比为60∶40)为流动相,流速0.8mL/min,检测波长290nm,柱温30℃进行液相色谱测定辣椒制品中的花椒油素。结果表明,花椒油素在0.001～0.04mg/mL范围内呈良好线性关系,加标平均回收率为96.8%,RSD为3.62%。该方法简便、准确,适用于辣椒制品中花椒油素含量的测定。