Characteristics of tiger nut milk: effects of milling

A standard method for the extraction of tiger nut milk has been introduced. It has been shown that, although milling duration improves the yield of tiger nut milk solids and its nutrient composition, there is a quantifiable loss of nutrient in the pressing residue during milk extraction. Milling duration improved the colloidal stability of the milk against creaming during 16 h of storage. A higher milling intensity resulted in the aggregation of biological polymers which resulted in colloidal destabilisation. Milling improved the lightness and stability and reduced browning rate of the tiger nut milk during storage. This report is important for the production of tiger nut milk of consistent and comparable characteristics. Milling has been introduced as a processing method for the qualitative and quantitative modulation of the properties of tiger nut milk. It is recommended to develop further strategies to improve the colloidal stability of tiger nut milk as a beverage.     

Chemical analysis of tiger nut (Cyperus esculentis)

Tiger nut, Cyperus esculentis L, is a tuber that grows and is consumed widely in West Africa. It is eaten unprepared, soaked in water, or dried and mixed with roasted peanuts. The purpose of this work was to determine the composition of tiger nut as part of its nutritional evaluation.     

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.     

Effect of tiger nut fibre on quality characteristics of pork burger

Horchata is a refreshing beverage obtained from tiger nut tubers that yields high amount of by-products. These by-products have a high content of fibre that allows its application in the development of dietary fibre rich foods. The utilization of increasing levels (0%-control, 5%, 10% and 15%) of tiger nut fibre (TNF), in the formulation of pork burgers was evaluated. This evaluation was based on: chemical composition, physicochemical, cooking characteristics and sensory properties of burgers. Pork burgers elaborated with TNF had higher nutritional value (higher fibre content) and better cooking characteristics (higher cooking yield, fat retention and moisture retention) than control burgers. Some of the negative changes in colour (a* decrease and b* increase) and texture (chewiness and springiness increase) parameters due to TNF addition observed in raw burgers were masked by the stronger modifications due to the cooking process. Burgers with TNF were perceived as less greasy, less juicy, more grainy and with less meaty flavour than controls; although this perception did not reduce the overall acceptability of burgers. Overall acceptability scores were slightly lower in burgers with 15% TNF, although no significant differences were detected with the scores of control, 5% and 10% TNF burgers. TNF addition to burgers is a promising and convenient application as dietary fibre of burgers was significantly increased without changes in sensory acceptance.     

油莎豆饼油的SiO2精炼处理研究

为探索SiO2处理对油莎豆饼超临界、亚临界流体萃取油品质的影响,分析比较了亚临界丁烷萃取油(Subcritical butane extraction oil,SBEO)和超临界 CO2萃取油(Supercritical CO2 extraction oil,SCO2EO)SiO2处理前后的品质指标.结果表明,2种萃取...     

Physico-chemical and functional properties of myofibrillar proteins from different species of molluscs

The physico-chemical and functional properties of myofibrillar proteins from scallop (Zygochlamys patagonica), bivalve molluscs (Aulacomya ater ater), and squid (Illex argentinus) were investigated. Actomyosins were studied by SDS-PAGE, Mg²⁺-(Ca²⁺-dependent) ATPase activity, reduced viscosity, and surface hydrophobicity determinations. The emulsion capacity (EC) of both soluble protein extracts and actomyosins was also determined. Densitometric analysis of the SDS-PAGE 10% gels showed that in comparison with the actomyosin from striated muscle of scallop, the actomyosins of Aulacomya, squid, and smooth plus striated muscle of scallop have a significant higher relative percentage of paramyosin and a lower relative percentage of myosin. The reduced viscosity of actomyosin from both striated and smooth plus striated adductor muscle of scallop was significantly lower than that of squid and Aulacomya. No significant differences were observed in the enzymatic activity of the actomyosins analysed. Surface hydrophobicity and EC of actomyosin from striated muscle of Aulacomya were lower than those corresponding to actomyosin of the other species. The highest values of EC were observed in extracts of squid mantle. In addition, the EC of the extracts was significantly higher than the EC of their respective actomyosins.     

Effects of partial hydrolysis on structure and gelling properties of oat globular proteins

The effects of partial hydrolysis and the environmental conditions (pH and temperature) on the gelling properties of oat protein isolate (OPI) were investigated. OPI was treated with flavourzyme, alcalase, pepsin and trypsin. The changes in protein structure were observed by SDS-PAGE, size exclusion high performance liquid chromatography (SE-HPLC) and amino acid analysis. Gel mechanical properties were evaluated by textural profile analysis (TPA). The results revealed that the acidic polypeptides (12S-A) of oat globulin exerted great influence over the gelling ability of oat protein. Partial hydrolysis by flavourzyme and trypsin could significantly improve oat protein gel strength, especially at pHs 8–9 by modulating the balance between the electrostatically repulsive force and the hydrophobic attractive force among polypeptide chains during the gelling process. The gels prepared with flavourzyme and trypsin treated oat proteins have comparable or higher mechanical strength than soy protein gels at neutral pH. At pH 9 the gel made of trypsin treated oat protein even showed comparable mechanical strength to egg white protein gels under the same pH. Both oat protein and its hydrolysate gel exhibited excellent water-holding capacity at neutral or mildly alkaline conditions. The results of this study indicate that oat protein has a promising potential to be used as new and cost-effective gelling ingredient of plant origin to provide texture and structure in food products.     

储藏条件对油莎豆及其油脂品质的影响

为了探究不同储藏条件对油莎豆及其油脂品质的影响,将油莎豆在不同的温度(15、35℃)和湿度(11%、97%)下储藏40 d,测定油莎豆的含水量和含油量,以及油莎豆油的脂肪酸组成、维生素E含量和傅里叶红外光谱特征变化。结果表明：高湿(97%)条件下油莎豆含水量显著增加;低温低湿(15℃、11%)条件下油莎豆的含油量最高,为28.73%,高温高湿(35℃、97%)条件下最低,为26.82%;不同储藏条件下油莎豆油的脂肪酸组成没有显著变化,但高温和低湿储藏条件导致油莎豆油中饱和脂肪酸和多不饱和脂肪酸含量升高,单不饱和脂肪酸含量降低;油莎豆油中维生素E含量为171.34～183.80 mg/kg,主要成分为α-生育酚(117.70～126.12 mg/kg)和β-生育酚(40.55～45.38 mg/kg),相对于其他条件,高温低湿(35℃、11%)条件下油莎豆油中维生素E损失最严重;在试验考察范围内,储藏条件未对油莎豆油的官能团和结构产生明显影响。综上,选择适当的储藏条件有利于油莎豆的安全储藏。     

Physico-chemical properties of potato starches

Starches were isolated and characterised from 10 potato cultivars grown under the same conditions (with a commercial starch for reference). The chemical composition revealed some differences amongst the starches with protein ranging from 0.30% to 0.34%, amylose 25.2% to 29.1% and phosphorus 52.6–66.2 mg 100 g⁻¹. High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more B1, but less A-chains, than cereal starches. Gelatinisation onset (T_o), peak (T_p) and conclusion (T_c) temperatures of the native potato starches ranged from 58.7 to 62.5 °C, 62.5 to 66.1 °C and 68.7 to 72.3 °C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4 J g⁻¹. The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The ¹³C magic angle spinning nuclear magnetic resonance (¹³C CP-MAS NMR) and wide angle X-ray diffraction (XRD) data (30.6% ± 0.22% crystallinity on average) showed little variance amongst the samples. Particle sizing results, however, revealed more variance (20.6–30.9 μm mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions.     

Physico-chemical and functional properties of proteins from spray dried algae (Spirulina platensis)

The nitrogen solubility index of proteins from Spirulina platensis as a function of pH in the range of 1 to 12 has been determined both in water and different concentrations of sodium chloride using the spray dried samples. Solubility characteristics show maximum solubility in the pH range of 8 to 10 in water and pH 6.0 ± 0.5 in 0.5 M sodium chloride. The ultraviolet and visible spectra have maxima at 285 and 620 nm, respectively. Fluorescence emission spectrum shows a maximum emission at 340 nm arising from tryptophanyl groups. The sedimentation velocity experiment shows two major fractions with sedimentation coefficient of 2.8 and 4.9 S. The functional properties of the protein are determined using the spray-dried sample. The result for water absorption (292 g/100 g), fat absorption (56 g/100 g), foaming and emulsion properties were determined and compared with egg protein as standard. An attempt is made to correlate the changes occurring as a result of spray drying of the functional properties to the physico-chemical properties of the protein in solution.     

油莎豆非油制品加工研究进展

油莎豆又称虎坚果,莎草科莎草属植物,原产于非洲,作为一种集粮、油、牧、饲于一体的新兴农作物已被我国引进种植。油莎豆具有较高的经济价值和开发潜力,其块茎不仅营养丰富,还具有降血压、降血脂、降低胆固醇等医学保健功能。从油莎豆主粮制品、饮品、发酵制品和其他制品几个领域,阐述了油莎豆非油制品加工的最新研究进展,并对其未来发展前景进行展望,以期为油莎豆块茎以及其提油后副产物的开发利用提供参考。     

油莎豆油基低饱和人造奶油的制备 及其在面包中的应用

为充分利用油莎豆油及改善人造奶油的营养品质,以油莎豆油和棕榈硬脂为原料制备人造奶油,与5种市售人造奶油的理化性质进行对比分析,并将其应用到面包制作中。结果表明:自制人造奶油的熔点（33.51 ℃）在5种市售人造奶油的熔点范围内（32.33~45.43 ℃）,且满足LS/T 3217—1987标准要求;自制人造奶油具有较好的延展性、抗渗油能力以及良好的口融性,同时拥有较低的饱和脂肪酸含量（ ＜40%）、动脉粥样硬化指数（0.56）和血栓形成指数（1.15）;与市售人造奶油相比,自制人造奶油具有较多的β′晶型以及较好的热性质;添加自制人造奶油的面包,具有较低的烘焙损失率、较大的比容和较好的感官评分。综上,自制人造奶油具有良好的发展潜力,有望代替市售人造奶油应用到面包、饼干、甜点等焙烤领域。     

Functional properties of proteins isolated from phorbol ester-free physic nut (Jatropha curcas L.) seed cake

Phorbol ester-free physic nut (Jatropha curcas L.) seed cake is a nutritious protein source. Functional properties of the protein isolates obtained from various protein precipitation methods were investigated. Proteins isolated from the seed cake by ammonium sulfate gave the highest yield. The solubility of all proteins increased with increasing pH with their maximum and minimum solubility at pH of 12.0 and 4.0, respectively. The protein prepared by ethanol provided the maximum water holding capacity (3.34 mL water/g protein). The oil binding capacities of all proteins were 1.96–2.03 mL oil/g protein. The protein precipitated by ethanol showed higher emulsion activity and stability than that precipitated by acetone and ammonium sulfate. The protein obtained from ammonium sulfate gave the highest foam capacity, while the protein from acetone had the highest foam stability. Different functional properties of the proteins were achieved by various protein precipitation methods. The protein isolate obtained from each method could serve as a food ingredient applied to food products requiring a specific functional property.     

水飞蓟蛋白组分的理化特性研究

以水飞蓟籽仁脱脂粉为原料,采用Osboren法分级提取4种蛋白组分,研究各蛋白组分的理化特性.结果显示:水飞蓟各蛋白组分主要以中、低分子质量蛋白为主,电泳条带主要集中分布在32.4～44.5 ku和14.5～24.8 ku两个区域,缺乏高分子质量蛋白,容易消化吸收;水飞蓟各蛋白组分的氨基酸组成合理,种类齐全,富含谷氨酸.其中球蛋白的氨基酸评分最高为83,醇溶蛋白的最低为53;谷蛋白的蛋白质效率比最高,清蛋白的体外消化率和蛋白质消化率校正的氨基酸分数最高,分别达到92.55％和0.73;各蛋白组分中清蛋白的溶解性、起泡性和乳化性最好,谷蛋白的持油性最高,醇溶蛋白的功能特性最差.     

微波预处理对油莎豆贮藏稳定性及其油脂 脂质伴随物含量的影响

旨在为提高油莎豆的贮藏稳定性，采用微波对油莎豆进行预处理，研究了冷藏（4 ℃）和常温（20~31 ℃）贮藏条件下油莎豆水分含量、脂肪酶活性及其油脂酸值和过氧化值的变化规律，同时测定了油莎豆油的脂肪酸组成和脂质伴随物含量。结果表明：在常温贮藏或冷藏过程中，油莎豆的水分含量、脂肪酶活性及油莎豆油的酸值、过氧化值均呈一定增长趋势，微波预处理显著降低了油莎豆的水分含量、脂肪酶活性和油莎豆油的酸值；常温贮藏和冷藏120 d后，704 W 处理270 s制备的油莎豆油的酸值（KOH）小于4 mg/100 g，显著低于未经微波预处理的油莎豆油，满足国标（GB 2716—2018）的要求；微波预处理对油莎豆油脂肪酸组成无显著影响，但能提高油莎豆油中生育酚和总酚的含量，其分别在400 W处理270 s、704 W处理210 s时达到最高，为41.70 mg/100 g和10.21 mg/100 g；经微波预处理后，油莎豆油植物甾醇含量总体较空白组有所降低，但保留率在73.05%以上。综上，微波预处理对油莎豆的安全贮藏及其油脂中脂质伴随物的溶出有积极作用。     

基于低场核磁共振技术研究油莎豆热泵干燥特性

为研究热泵干燥技术对油莎豆干燥过程的影响,选取4种不同热泵温度,利用6种薄层干燥模型和低场核磁共振技术分析油莎豆在热泵干燥中的干燥特性、水分分布状态及其变化规律。结果表明：70 ℃热泵温度所用时间较40 ℃缩短了61.9%;得出Logarithmic模型能最好的描述油莎豆的热泵干燥过程,R2均＞0.99;低场核磁共振（LF-NMR）横向弛豫图谱显示油莎豆内不易流动水与自由水是热泵干燥过程中水分流失的主要来源;峰面积变化曲线图显示不同热泵温度对不同状态水分的散失和迁移的影响程度不同;热泵温度越高,核磁成像技术（MRI）图中红色区域消失越快;根据扫描电镜图发现70 ℃时油莎豆内部结构被严重破坏,不建议70 ℃以上温度干燥油莎豆。该研究可以为油莎豆热泵干燥工艺设计和水分动态变化研究提供理论参考。     

龙眼核淀粉颗粒性质的研究

以龙眼核为原料,提取并纯化龙眼核淀粉,对龙眼核淀粉的颗粒形貌、X-光衍射图样、直链和支链淀粉含量、溶解度和膨胀度等特性进行了研究。结果表明,龙眼核淀粉颗粒的大小为5.5～15μm,平均粒径为9.3μm,多呈半椭圆形,具典型的偏光十字,无明显的层状结构;用偏十字消光法测定淀粉糊化温度,糊化起始、终止温度分别为63.8、70.3℃;该淀粉的直、支链淀粉分别为20.5%、79.5%;淀粉的溶解度和膨胀度不同于玉米和马铃薯淀粉。     

Interactions between globular proteins and procyanidins of different degrees of polymerization

Interactions of proteins with phenolic compounds occur in food products containing vegetable sources, such as cocoa, cereals, or yogurts containing fruit. Such interactions can modify protein digestion and protein industrial properties. Noncovalent interactions between globular proteins (proteins important in industry) and procyanidins (phenolic compounds present in large quantity in fruits) were studied. The affinity constants between procyanidins of various average degrees of polymerization () and lysozyme or α-lactalbumin were measured by isothermal titration calorimetry. The effects of these interactions on protein solubility and foam properties were examined using α-lactalbumin and BSA. Weak interactions were found with epicatechin and procyanidin dimers. Procyanidins of n = 5.5 and n = 7.4 showed medium (1.5 × 10⁵M⁻¹) and high (8.69 × 10⁹M⁻¹) affinities, respectively, for α-lactalbumin at pH 5.5, with n the average number of subunits per oligomer. A positive cooperativity of binding at low procyanidin:protein molar ratios was observed. The affinities of α-lactalbumin and lysozyme for procyanidins increased when the pH was close to the isoelectric pH. Solubility of lysozyme was strongly decreased by procyanidins of n = 5.5, whereas α-lactalbumin and BSA were less affected. Protein solubility in the presence of procyanidins was not affected by increased ionic strength but increased slightly with temperature. Procyanidins of n = 5.5 and n = 7.4 stabilized the average bubble diameter of foam formed with α-lactalbumin but had no effect on foam made from BSA. These results indicate that procyanidins of medium can lead to an undesirable decrease of protein solubility, but may play a positive role in foam stability.