Effects of tiger nut (Cyperus esculentus) milk liquid co‐products on the quality of pork burgers

Co‐products from the tiger nut milk industry can be given added value if they are used in the manufacturing process of other food products. The aim of this study was to analyse the effect of using tiger nut milk liquid co‐product as a substitute for the water added to pork burger formulations. The results showed that its use in pork burger delayed lipid oxidation and improved cooking properties (less shrinkage), while no significant changes in nutritional value were observed. Pork burgers containing tiger nut liquid co‐product were perceived to be juicier and less fatty than the control, contributing to higher scores for overall liking.     

Addition of crude tiger nut protein extract affects stiffness of enzymatically cross‐linked dairy proteins

The influence of crude tiger nut protein extract on the gel properties of enzymatically cross‐linked dairy proteins was investigated. Enzymatic cross‐linking of dairy proteins in the presence of crude tiger nut proteins caused the formation of larger casein polymers and increased the degree of polymerisation. Gel stiffness of acidified products containing whey proteins was higher when cross‐linking occurred in the presence of crude tiger nut proteins. The results are relevant for improving the textural characteristics of acidified aqueous tiger nut extract (tiger nut milk) enriched in dairy proteins.     

Impact of Dry-milled Germ Processing on Aqueous Protein and Oil Extraction

Reduced petroleum cost and public objection to using corn for bioenergy rather than food have challenged grain ethanol producers to come up with new bioprocess and coproducts that can add value but maintain ethanol cost competitiveness. Novel dry and wet milling fractionation processes of corn that could generate higher value coproducts and improve coproduct economics, long-term outlook, and economic stability of corn processing plants have been being recently proposed. Germ Wet Milling? is such novel aqueous processing method designed to increase germ protein and oil concentration by water soaking and wet fractionation of dry-milled corn germ. The goal of this study was to investigate the sequential oil and protein extraction after Germ Wet Milling and to develop economically viable processes for producing protein concentrates. Corn protein concentrates were prepared after aqueous processing of dry-milled germ using membrane filtration or isoelectric precipitation. The amount of protein recovered was a function of the protein dispersibility index of the starting material, which depended on soak temperature and time. Extracts prepared after Germ Wet Milling? contained 59.1 to 64.7 % protein (db), while concentrates had 64.9 to 82.4 % protein. The technique used for protein recovery also influenced the mass and protein yield and composition. For all treatments, membrane filtration was a more effective method than isoelectric precipitation for recovering protein from extract. Aqueous enzymatic oil extraction (AEOE) was used to evaluate the oil recovery potential after Germ Wet Milling. The effect of enzyme dosages and/or elimination of the acidic protease on oil extraction from high protein, high protein dispersibility index (PDI) corn germ and high protein, low PDI corn germ were evaluated. AEOE using a combination of cellulases and xylanase (Optimash XL®), an acidic protease (Fermgen®), and a basic protease (Optimase®) resulted in oil recoveries as high as 71.9 % of the initial oil content. A twofold reduction in enzyme dosages was possible with little or no effect on oil recoveries for both types of germ.     

Untargeted metabolomics reveals links between Tiger nut (Cyperus esculentus L.) and its geographical origin by metabolome changes associated with membrane lipids

ABSTRACT

Tiger nuts and tiger nut milk are well-known Valencian products, and step-by-step these tubers and the tuber-based beverage are becoming more and more relevant products in international markets. However, the increasing demand and success of Valencian tiger nuts did not allow protected designation of origin (PDO) tuber to supply the domestic and international markets. Therefore, the verification of the geographical origin is highly required. In this research, the main objective was to combine an advance analytical method and chemometrics tools in order to decipher the geographical origin of 45 tiger nut samples from (i) ‘Xufa de València’ PDO and (ii) African samples. The analytical method, based on solid-liquid extraction followed by ultra-high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC-HRMS) metabolomics approach, highlighted sensitivity and wide linear dynamic range in order to simultaneously analyse polar and non-polar metabolites. After data processing, a pronounced sample clustering according to the geographical origin was clearly observed using unsupervised models, and supervised models revealed that tiger nuts lipidome was associated with the geographical origin. As a result, African samples highlighted an overexpression of phospholipids, such as phosphatidylethanolamine 34:1, and triacylgricerols crosslinked to environmental stress and alteration of membrane lipid compositions.     

Untargeted metabolomics reveals links between Tiger nut (Cyperus esculentus L.) and its geographical origin by metabolome changes associated with membrane lipids

Tiger nuts and tiger nut milk are well-known Valencian products, and step-by-step these tubers and the tuber-based beverage are becoming more and more relevant products in international markets. However, the increasing demand and success of Valencian tiger nuts did not allow protected designation of origin (PDO) tuber to supply the domestic and international markets. Therefore, the verification of the geographical origin is highly required. In this research, the main objective was to combine an advance analytical method and chemometrics tools in order to decipher the geographical origin of 45 tiger nut samples from (i) ‘Xufa de València’ PDO and (ii) African samples. The analytical method, based on solid-liquid extraction followed by ultra-high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC-HRMS) metabolomics approach, highlighted sensitivity and wide linear dynamic range in order to simultaneously analyse polar and non-polar metabolites. After data processing, a pronounced sample clustering according to the geographical origin was clearly observed using unsupervised models, and supervised models revealed that tiger nuts lipidome was associated with the geographical origin. As a result, African samples highlighted an overexpression of phospholipids, such as phosphatidylethanolamine 34:1, and triacylgricerols crosslinked to environmental stress and alteration of membrane lipid compositions.     

Quality characteristics of horchata (a Spanish vegetable beverage) treated with pulsed electric fields during shelf-life

The application of pulsed electric fields (PEF) is one of the new non-thermal technologies being studied to evaluate their potential as alternative or complementary processes to thermal pasteurization. “Horchata de chufa” (tiger nut milk or earth almond milk) is of high nutritional quality and therefore has great potential in the food market, limited by its very short shelf-life. The present work studies whether PEF can be used to obtain a quality horchata and increase its shelf-life while maintaining its organoleptic characteristics. In order to do so we determined pH, total fat, peroxide index, thiobarbituric acid-reactive substances index, formol index, and peroxidase activity in natural (untreated) horchata and horchata subjected to various PEF treatments and studied their stability during refrigerated storage (2–4 °C). After PEF treatment, only peroxidase activity decreased significantly (p < 0.05). This parameter and pH varied during the shelf-life of the horchata, and a negative correlation was obtained between pH and peroxidase activity.     

Invited review: spray-dried dairy and dairy-like emulsions--compositional considerations

Milk constituents [caseins, whey proteins (WP), lactose, and anhydrous milk fat] are used widely in the manufacture of dehydrated dairy and dairy-like emulsions. When sodium caseinate- (NaCas) and WP-stabilized emulsions with an oil-to-protein ratio ranging from 0.25 to 5 are dehydrated, NaCas is a more effective encapsulant than WP because of its superior emulsifying properties and resistance to heat denaturation. Denaturation degree of WP during drying has been associated with increased powder surface fat and larger droplet size after reconstitution. Encapsulation of NaCas-stabilized emulsions improves in the presence of lactose; powder surface fat was reduced from 30 to <5% when lactose was added at a 1:1 ratio to NaCas in an emulsion containing 30% (wt/wt) oil. This has been related to the ability of lactose to form solid-like (or glassy) capsules during sudden dehydration. Encapsulation of WP-stabilized emulsions is not improved by addition of lactose, although there are conflicting reports in the literature. Storage stability of dehydrated dairy-like emulsions is strongly linked to lactose crystallization as release of encapsulated material occurs during storage at high relative humidities (e.g., 75%). The use of alternative carbohydrates as “matrix-forming” materials (such as maltodextrins or gum arabic) improves storage stability but compromises the emulsion droplet size after reconstitution. The composition of the powder surface has been recognized as a key parameter in dehydrated emulsion quality. It is the chemical composition of the powder surface that dictates the behavior of the bulk in terms of wettability, flowability, and stability. Analyses, using electron spectroscopy for chemical analysis of the surface of industrial milk powders and dehydrated emulsions that mimicked the composition of milk, showed that powder surface is covered mainly by fat, even when the fat content is very low (18 and 99% surface fat coverage for skim milk and whole milk powders, respectively). The functional properties of milk constituents during emulsion dehydration are far from being thoroughly understood; future research needs include a) the encapsulation properties of pure micellar casein; b) a deeper understanding of colloidal phenomena (such as changes in the oil-water and air-oil interfaces) that occur before, during, and after dehydration, which ultimately define emulsion stability after drying; and c) reconciliation of the current different views on powder surface composition.     

乳清蛋白对直接超高温乳贮存稳定性的影响研究进展

直接超高温（direct ultra-high temperature,dUHT）牛乳是蒸汽直接接触牛乳快速加热,然后通过闪蒸迅速蒸发水分,具有热负荷能低、最大程度保留牛乳营养和风味等优点,有望成为继UHT乳的新一代高品质液态乳制品。目前我国dUHT乳产业尚处于起步阶段。虽然dUHT乳的营养全面,但其贮存过程中有时出现沉淀、老化凝胶等品质问题,影响了产品货架期。dUHT乳的贮存稳定性影响因素非常复杂,乳清蛋白的热不稳定性是影响dUHT乳贮存稳定性的主要原因之一。本文综述了dUHT乳生产基本原理,探讨了乳清蛋白分子间、乳清蛋白与酪蛋白和纤溶酶等物质之间的交联反应机制及其对dUHT乳贮存稳定性的影响,以期为dUHT乳的加工技术优化升级和我国dUHT乳的快速发展提供参考。     

堆酿pH值对纤丝干酪成熟期化学指标的影响

研究加工过程中不同堆酿pH值的纤丝干酪在后熟过程中可榨乳清含量、滴定酸度、蛋白质水解及游离脂肪酸含量的变化趋势。结果表明:堆酿pH值对纤丝干酪的后熟过程中可榨乳清含量、滴定酸度和蛋白水解有影响,对纤丝干酪游离脂肪酸含量影响较小。     

Effect of green tea catechins on physical stability and sensory quality of lactose-reduced UHT milk during storage for one year

Ultra-high temperature (UHT) processed lactose-reduced milk containing added green tea extract (GTE) at two concentrations (0.1% and 0.25%) was stored at 22 ± 2 °C for one year. The effect of GTE addition on physical stability, protein binding, and sensory quality was evaluated. Sedimentation in skim milk and creaming of full fat milk were inhibited by addition of GTE. The formation of Maillard-related flavour compounds was inhibited during storage as determined by dynamic headspace GC–MS. Using Western blot analysis, milk proteins were found to be highly conjugated to polyphenols. Addition of GTE before UHT treatment resulted in increased bitterness and astringency in UHT milk and this remained during storage. Even though GTE addition improved the physical stability and inhibited Maillard reactions in the milk, the taste and flavour contribution from GTE was dominating throughout storage, and alternative sources of polyphenols should be explored for increasing shelf-life stability of long-life milk.     

低耗水管道化制浆技术对豆浆品质及稳定性的影响

通过开展低耗水管道化制浆技术对豆浆品质及稳定性进行研究,对比分析不同制浆工艺所得豆浆的基本组分、粒径、离心沉淀率、稳定性、色差和感官评价等指标的差异。结果表明：新型低耗水浸泡技术结合胶体磨制浆得到的豆浆蛋白质浸提效果（3.89 g/100 g）最佳;平均粒径（2.55 μm）相对较小,粒径峰值较高、峰宽较窄,分布均一;离心沉淀率（1.81%）及稳定性指数斜率最低,体系稳定性显著高于传统技术制备的豆浆（P＜0.05）;豆浆颜色亮白、口感细腻,感官评分为96.20 分,感官品质显著优于其他处理组（P＜0.05）。低耗水浸泡技术结合胶体磨制浆可有效提高大豆蛋白提取率,减小豆浆粒径,改善豆浆稳定性和感官品质,为豆制品管道化加工提供参考。     

The stabilisation of acidified whole milk drinks by carboxymethylcellulose

Carboxymethylcellulose (CMC) was used as a stabiliser for acidified whole milk drinks. The stability of the acidified whole milk drinks was investigated by observation of the evolution of size and zeta potential of colloidal particles during acidification along with sedimentation measurement and was compared with the stability of acidified skim milk drinks. It was found that the presence of fat resulted in larger particle sizes, but it did not disturb the absorption of CMC onto casein micelles below pH 5.2. The absorption of CMC endows the casein micelles with electrostatic and steric repulsions, essential to the stability of the acidified milk drinks. Acidified whole milk drinks can be stabilised by CMC, which is capable of effectively preventing the unwanted creaming of fat embedded in the clusters of CMC and caseins as well as preventing the aggregation of casein micelles as it did in skim milk drinks.     

Lipolysis and Oxidation in Ultra‐High Temperature Milk Depend on Sampling Month,Storage Duration,and Temperature

During storage, some factors (for example, storage duration and temperature) can affect milk stability and consumer acceptability. Thiobarbituric acid reactive substances (TBARSs), lipid classes, and fatty acid profiles in stored ultra‐high temperature (UHT) milk were analyzed to assess the effects of storage time and temperature on lipid oxidation and lipolysis. With storage duration up to 12 months, the milk fat phase was separated and showed high levels of oxidation and lipolysis, manifested as increased levels of TBARS and free fatty acids. High oxidation levels decreased the percentage of unsaturated fatty acids (UFAs) in triacylglycerol and phospholipids. Higher storage temperatures (20, 30, and 37 °C) resulted in a higher degree of fat aggregation, oxidation, and lipolysis compared with refrigerated storage (4 °C). Additionally, sampling month of raw milk (May, July, and November) affected the lipid profiles of UHT milk during storage, with more UFA oxidized in July than in the other 2 months.     

A preliminary study of the quality attributes of a cloudy wheat beer treated by flash pasteurization

Flash pasteurization (37 and 100 pasteurization units, PU) and conventional tunnel pasteurization (15 PU) processing of wheat beers were evaluated by examining their impacts on microorganisms, colour, colloidal haze and flavour stability during 84 days of storage at 20°C. The results revealed that the microbiological stability of 37 and 100 PU flash‐pasteurized beers was comparable with that of the 15 PU sample, and the development of both yeast and lactic acid bacteria was inhibited for 84 days of storage. The conventional tunnel‐pasteurized wheat beer resulted in a higher thermal load relative to the flash‐pasteurized samples based on the results of oxidative stability. These three pasteurized beers showed a similar decrease in haze intensity throughout the storage period. Meanwhile, flash‐pasteurized beers had better colour and colloidal haze stability than the tunnel‐pasteurized beer. It was also found by dynamic light scattering analysis that the temperature in the flash pasteurizer has the desired effect on the protein denaturation and particle size distribution. Therefore, flash pasteurization is a promising method to increase the shelf‐life of wheat beers instead of conventional tunnel pasteurization. Copyright © 2017 The Institute of Brewing & Distilling     

Functional,Thermal and Rheological Properties of High Fibre Fresh Pasta: Effect of Tiger Nut Flour and Xanthan Gum Addition

Tiger nut flour (TNF) is a rich source of dietary fibre with potential to be used in cereal-based products. However, research on improving the rheological properties of tiger nut-based doughs is limited. In this paper, the significance of TNF and xanthan gum (X) incorporation into fresh egg pasta, in terms of its thermal and dynamic rheological properties, has been investigated. Plain semolina pasta (DWS) was used as control. High fibre doughs (20 and 40% TNF) with or without X (0 and 1%) were assessed. Both fundamental (dynamic oscillatory and creep tests) and empirical (texture profile analysis) tests were performed to assess the viscoelasticity of TNF-DWS composite blends. Raw solids (TNF, DWS) were characterised in terms of their chemical composition, particle size distribution and functional properties. For both fresh and cooked pasta, water activity, water content and gelatinisation temperatures were estimated. The results from the rheological tests revealed that partial replacement of DWS by TNF lead to less cohesive and weaker structures due to the lower presence of a gluten network. X significantly improved the rheological response of the TNF-based doughs. Thermal analysis showed a single endothermic peak in the temperature range between 60 and 78 °C during heating, which corresponds to the amylopectin gelatinisation. However, when replacing 40% of DWS by TNF, two-phase transitions were observed, probably associated to the starch tiger nut gelatinisation or the formation of amylose-lipid complexes. The optimum cooking time for the tiger nut pasta was 2 min as determined by a calorimetric analysis.     

槟榔果仁油理化性质及氧化稳定性研究

为探讨槟榔果仁油理化性质和存贮稳定性,依据中国食用油标准探讨其理化指标,并通过测定过氧化值变化探讨光照、温度、氧气和抗氧化剂对其稳定性的影响。结果表明,槟榔果仁油提纯前后理化性质有所变化,提纯后槟榔果仁油碘值、水分含量等符合中国国标要求;利用超临界CO2提取的槟榔油提纯后折光指数为1.468 0,碘价为198gI2/100g,皂化价为194.3mgKOH/g,酸价为0.89mgKOH/g,过氧化值为0.50meq/kg,各项指标均符合食用油脂理化性质要求,油脂碘价与折光指数较高。光照、高温都对槟榔油的过氧化有明显的促进作用,且温度影响显著;同一时间和温度,与空气接触面积越大过氧化速度越快;试验表明常用的抗氧化剂能防止油脂在高温下发生氧化,其中TBHQ抗氧化效果最好,PG、BHT次之,BHA效果最不明显。     

乙二胺四乙酸二钠-盐酸副玫瑰苯胺检测干果中二氧化硫的方法研究

本研究对盐酸副玫瑰苯胺法测定食品中SO2进行改进,以EDTA-2Na代替剧毒试剂四氯汞钠,建立了超声波浸提、无汞盐吸收液检测干果SO2残留的方法,二氧化硫含量在0～10.0μg范围内与吸光度呈良好的线性关系(R2=0.9995),方法的检出限为0.8mg/kg。测定样品的相对标准偏差在3.29%～7.42%之间,回收率在89.17%～104.72%之间。该方法操作简便、重现性好、线性范围宽、减小了对环境的污染,可用于干果中亚硫酸盐的测定。     

Nutrient and antinutrient composition of pearl millet grains as affected by milling and baking

Milling of pearl millet grains reflected a change in gross chemical composition. Baking did not cause a significant change in nutrient content of raw pearl millet flour. Milling and heat treatment during chapati (an unleavened bread) making lowered polyphenols and phytic acid and improved the protein digestibility and starch digestibility to a significant extent.     

液态羊乳的加工研究进展

进入营养健康时代,消费需求不断升级,功能、营养、个性化的产品越来越受到重视.羊乳一直是人类营养的重要组成部分,与牛乳相比,羊乳的营养价值相对较高,凝乳的形成更柔软,乳脂肪小球的比例更高,致敏性低,与人乳更接近,是许多重要营养素的良好膳食来源.除了羊乳的许多有益作用外,饲养山羊和绵羊的优势,如动物成本较低、对饲料和水的需...     

花生蛋白奶的乳化稳定性及感官方差分析

本文研究了乳化剂及其与增稠剂的配合对花生蛋白奶的稳定效果，以离心测试模拟其贮藏期稳定性情况是快速、可靠的检验方法。为获得色、香、味俱佳的新产品，可以方差分析作顺序判断的感官鉴定。