Effect of cold plasma on the techno-functional properties of animal protein food ingredients

Proteins, as food ingredients, are employed in the food industry, not only for their high nutritional value, but also because of their techno-functional properties. Modifications of their native structure due to the action of external factors such as pH, temperature or processing by emerging technologies, can lead to changes in their functionality; and consequently, their applicability. The present study investigates the effects of cold atmospheric air plasma on the techno-functional properties of two common food ingredients (haemoglobin and gelatine from pork), and a novel source of functional proteins extracted from a meat co-product (bovine lung protein). Significant effects were found for their functional, rheological and gelling properties. However, the effects were found to depend on the native structure and nature of the protein. The findings point to the specific nature of plasma-protein interactions and the need for individual proteins to be studied as a function of plasma conditions.Industrial relevance textCold plasma is increasingly being investigated as a non-thermal technology for food and other biological applications such as primary agriculture and medicine. In addition to microbial and pest decontamination, it can be also be used to modify the functionality of food ingredients to achieve the desired properties of a specific food product.     

贮藏时间对造纸法再造烟叶抗张强度和热失重特性的影响

目的：了解造纸法再造烟叶在贮藏过程中内在化学成分、抗张强度和热失重特性随时间变化的规律,获得再造烟叶最佳使用时间。方法：对不同贮藏时间下3种造纸法再造烟叶（JS-A、JS-B和JS-C）的常规化学成分、抗张强度和热失重特性进行分析比较。结果：JS-A和JS-B样品的总植物碱、总糖、总氮和水分含量随贮藏时间增加变化显著,JS-C样品的总植物碱和总氮含量变化不显著。贮藏时间对3种再造烟叶的纵向抗张强度影响显著,均在180 d时出现最大值。3种样品的第二阶段失重率和归一化热焓值随贮藏时间的增加有显著变化,均在360 d时达到最大值。结论：3种再造烟叶适宜的贮藏时间为180～360 d。     

The effect of tuber pre-heating temperature and storage time on the mechanical properties of potatoes

Changes in mechanical properties of potatoes are known to affect the quality of the products processed from the tubers. This study set out to ascertain the extent to which the changes in mechanical properties were attributable to turgor changes in the course of a storage season versus physiological changes that are expected to occur due to tissue ageing. Specimens taken from two potato cultivars (Russet Burbank and Shepody) of two different solids contents were subjected to small strain oscillatory shear tests and wedge-penetration fracture tests. Prior to mechanical testing, specimens prepared from control (8°C) and pre-heated (33, 47 or 60°C) potato tubers were osmotically adjusted in a mannitol solution of 3, 5 or 7%. The tests were repeated every month from November to June. Turgor pressure and specific gravity were also measured during storage: turgor pressure slightly decreased, while specific gravity increased slightly throughout the storage period. Control and pre-heating temperatures of 33 and 47°C had little or no influence on shear modulus or fracture toughness; at a given mannitol concentration, pre-heating at 60°C caused both parameters to decrease. As mannitol concentration increased, the mechanical properties investigated decreased for the control, as well as for 33 and 47°C pre-heating treatments. Mannitol concentration had no effect on shear modulus and toughness for tubers that had been pre-heated at 60°C. Storage time had only a slight effect on the parameters of interest. Solids content and cultivar had no significant effect on either shear modulus or fracture toughness. To conclude, mechanical properties of tubers did change in storage, but the changes were much less pronounced than the changes caused by adjustment of turgor pressure. Thus, cell moisture content and its effect on turgor pressure affects tissue mechanical properties more dramatically than changes associated with ageing.     

Effect of enzymatic hydrolysis on molecular weight distribution,techno-functional properties and sensory perception of pea protein isolates

Pea protein isolate (Pisum sativum “Navarro”) was hydrolyzed with 11 proteolytic enzymes at different hydrolysis times (15, 30, 60, and 120 min) to improve techno-functional and sensory properties. The degree of hydrolysis and changes within the molecular weight distribution were used as indicators for a reduced allergenic potential. The highest degree of hydrolysis was reached by Esperase hydrolysates (9.77%) after 120 min of hydrolysis, whereas Chymotrypsin hydrolysates showed the lowest (1.81%). Hydrolysis with Papain, Trypsin, Bromelain, Esperase, Savinase, and Alcalase suggested an effective degradation of the 72 kDa-convicilin fraction. Papain and Trypsin hydrolysates showed a degradation of the 50 kDa-mature vicilin after 15 min of hydrolysis. Most hydrolysates showed a significant increase in protein solubility at pH 4.5 at all times of hydrolysis. Trypsin hydrolysates showed the highest foaming (2271%) and emulsifying (719 mL/g) capacities. The bitterness of the hydrolysates was strongly correlated (P < 0.05) with the degree of hydrolysis. In general, enzymatic hydrolysis improved techno-functional properties indicating their potential usage as food ingredients.Industrial relevanceDue to their high protein content, peas are becoming an attractive ingredient for the food industry. However, pea protein isolates are often characterized by poor techno-functional and sensory properties. Enzymatic hydrolysis is known to change the molecular weight distribution of proteins. Consequently, the techno-functional and immunogenic properties might be altered selectively. In this study, enzymatic hydrolysis was applied, resulting in highly functional pea protein hydrolysates with a hypothesized reduction of main allergens. The lower bitter perception highlights their high potential as valuable functional food ingredients.     

化学交联与酶法交联对鱼糜-明胶复合膜性质的影响

研究比较了戊二醛和谷氨酰胺转氨酶(TGase)对鱼糜-明胶复合膜的性质改良效果。当戊二醛的含量为蛋白质量的0.025%～0.1%时,膜的抗拉伸强度(TS)没有显著差异,但断裂延伸率(EAB)却随着戊二醛含量的增加而上升,当戊二醛含量增加到0.2%时,TS和EAB都出现了下降。然而,膜的TS和EAB都随着TGase的添加逐渐增加。虽然戊二醛和TGase都可以使蛋白发生交联,导致膜的固形物溶解率(FS)和蛋白溶解率(PS)下降,但是戊二醛的添加效果明显优于TGase。此外,戊二醛的添加会使膜的颜色变黄,而TGase不仅不会影响膜的色泽,还可以提高膜的透明性能。根据SDS-PAGE的结果,发现戊二醛和TGase都会使膜中蛋白分子发生交联形成高分子聚合物。FT-IR的分析结果表明,蛋白分子间的氢键作用随着TGase的添加逐渐减弱,随着戊二醛的添加出现先减弱后增强的趋势。     

Legume byproducts as ingredients for food applications: Preparation,nutrition, bioactivity,and techno-functional properties

The demand for high-quality alternative food proteins has increased over the last few decades due to nutritional and environmental concerns, leading to the growing consumption of legumes such as common bean, chickpea, lentil, lupin, and pea. However, this has also increased the quantity of non-utilized byproducts (such as seed coats, pods, broken seeds, and wastewaters) that could be exploited as sources of ingredients and bioactive compounds in a circular economy. This review focuses on the incorporation of legume byproducts into foods when they are formulated as flours, protein/fiber or solid/liquid fractions, or biological extracts and uses an analytical approach to identify their nutritional, health-promoting, and techno-functional properties. Correlation-based network analysis of nutritional, technological, and sensory characteristics was used to explore the potential of legume byproducts in food products in a systematic manner. Flour is the most widely used legume-based food ingredient and is present at levels of 2%–30% in bakery products, but purified fractions and extracts should be investigated in more detail. Health beverages and vegan dressings with an extended shelf-life are promising applications thanks to the techno-functional features of legume byproducts (e.g., foaming and emulsifying behaviors) and the presence of polyphenols. A deeper exploration of eco-friendly processing techniques (e.g., fermentation and ohmic treatment) is necessary to improve the techno-functional properties of ingredients and the sensory characteristics of foods in a sustainable manner. The processing of legume byproducts combined with improved legume genetic resources could enhance the nutritional, functional, and technological properties of ingredients to ensure that legume-based foods achieve wider industrial and consumer acceptance.     

酶法交联对花生分离蛋白理化与功能特性的影响

采用转谷氨酰胺酶(TGase)对花生分离蛋白(PPI)进行交联改性,比较了TGase在37℃下催化不同时间(0～240min)对PPI理化与功能特性的影响。结果表明,TGase可促使PPI亚基发生改变并形成高分子聚合物,同时使PPI的游离巯基含量降低,表面疏水性增加。随着交联程度的上升,PPI在pH3.0～10.0的溶解性逐渐降低,其制备的乳状液表面积平均粒径(d32)趋于增大,但适度交联(37℃下交联90min)可明显改善蛋白乳状液的稳定性。     

Effects of cross-linking and acetylation on oat starch properties

Starch samples separated from oat were modified with two different levels of POCl₃ (0.5 and 1.0 g kg⁻¹) as a cross-linking agent and two different levels of acetic anhydride (6% and 8% (w/w)) for acetylation. Swelling factor, thermal properties and retrogradation measurements were evaluated to characterise the influence of phosphorylation and acetylation on oat starch. Cross-linking decreased the swelling factor and did not improve gelatinization temperature while it increased synaeresis in comparison with native starch. Acetylation increased swelling factor but reduced gelatinization temperature and synaeresis of oat starch.     

Influence of enzymatic cross-linking on milk fat globules and emulsifying properties of milk proteins

The enzyme transglutaminase (TGase) can modify dairy protein functionality through cross-linking of proteins. This study examined the effects of TGase treatment on milk fat globules and the emulsifying properties of milk proteins. The extent of TGase-induced cross-linking of caseins increased with incubation time, with no differences between whole and skim milk. Extensive clustering of fat globules in extensively cross-linked raw whole milk occurred on homogenisation at 400 or 800 bar. Considerably less clustering of fat globules was observed when recombined milk (90 g fat L^–1) was prepared from TGase-treated skim milk and homogenised at 400 or 800 bar. TGase treatment did not affect fat globule size in cream, but prevented coalescence of fat globules therein, possibly through cross-linking of milk fat globule membrane components. TGase-induced cross-linking of milk proteins affected their emulsifying properties and may increase the stability of natural milk fat globules against coalescence.     

Effect of enzymatic cross-linking of milk proteins on functional properties of set-style yoghurt

This paper presents research on the effect of enzymatic cross-linking of milk proteins on the properties of yoghurt. Whole milk was incubated with transglutaminase (TG) prior to fermentation (2 h, 40°C, E/S ratio 1/2000). Enzyme action was stopped by heating (1 min, 80°C). Skim-milk was treated by simultaneous use of TG and thermophilic yoghurt starter culture without inactivation of the enzyme. A TG treatment of milk prior to fermentation led to prolonged fermentation, while the concomitant use of TG and culture had no influence on fermentation time. Post acidification of yoghurt during storage was lower for products from enzyme-treated milk. This applies both for products cross-linked prior to fermentation with enzyme inactivation, and for simultaneous use of culture and TG without inactivation of the enzyme. Scanning electron microscopic studies revealed that a TG treatment of milk led to reduced mesh sizes of the protein network, and a more regular distribution of the proteins in the yoghurt gel. As a result, yoghurt products from enzyme-treated milk showed increased gel strength and less syneresis, especially when the enzyme was not inactivated. Sensory studies revealed that odour and consistency properties of products from TG-treated milk were assessed as less 'yoghurt specific'. On the other hand, products from enzyme-treated milk were described as being more creamy, indicating that a TG treatment may simulate fat in fermented milk products.     

交联酯化作用对木薯麦芽糊精性能的影响研究

探讨了交联作用和酯化作用对木薯麦芽糊精的吸湿性能、表面活性、表观黏度、特性黏度、热力学性质的影响.结果显示,交联和酯化作用可以明显降低麦芽糊精的吸湿性,酯化作用比交联作用更能降低麦芽糊精溶液的表面张力,酯化作用比交联作用更能提高特性黏度.用POCl3进行交联没有改变麦芽糊精回生的起始温度和峰温,但结束温度和回生热焓有所上升,而酯化作用降低了起始温度、峰温和回生热焓.     

酶解时间对葵花11S球蛋白结构和功能性质的影响

以脱脂后的葵花籽粕为原料制备了葵花11S球蛋白,并利用碱性蛋白酶Alcalase酶解(控制酶解时间30、60、90、120 min)制备4种酶解产物,探讨酶解时间对酶解产物蛋白质结构和功能性质的影响。凝胶色谱分析结果表明,酶解产物的相对分子质量显著下降;圆二色谱分析结果表明,酶解产物的无规则卷曲结构增加;功能性质分析结果表明,酶解产物在p H 2~9范围内可溶性氮含量达80%以上,短时间酶解产物的起泡性和乳化性提高,但长时间酶解导致产物的泡沫稳定性和乳化性下降。     

植物基人造肉研究进展

豆粕作为优质植物蛋白质资源,探究利用大豆粕替代大豆分离蛋白作为高水分挤压植物蛋白肉加工原料的可能性,对生产企业控制生产成本及提高大豆粕经济价值都具有重要意义。本文以大豆粕为原料,通过测定硬度、弹性、咀嚼度、色泽、持水性、持油性、化学交联作用力等指标,以及利用傅里叶红外光谱和扫描电子显微镜等技术,系统地探究水分添加量（10.5、11、11.5、12、12.5 kg/h）对高水分挤压植物蛋白肉的品质及结构特性的影响。结果表明,随着挤压过程中水分添加量的增加,植物蛋白肉的硬度、弹性、咀嚼性均显著（P<0.05）下降,而亮度值、持水性和持油性均呈先升高后降低的趋势,并在水分添加量为11.5 kg/h时,植物蛋白肉具有较好的品质特性和外观色泽,内部形成了更加致密的纤维细丝,组织蛋白层状结构变得清晰整齐,呈现出精细的定向结构。傅里叶红外光谱与化学交联结果表明水分添加量对植物蛋白肉的结构具有影响显著,并且其结构由共价键和非共价键的交互作用共同维持。

     

淀粉种类对重组粉面团的流变学特性的影响

选取7种不同淀粉与谷朊粉重组,对重组粉面团的流变学特性和微观结构进行研究,探讨淀粉种类是否是影响重组粉面团性质的主要原因。研究表明:淀粉类型能明显影响重组粉面团的流变学特性和微观结构。各重组面团的动态频率扫描的恒定应变值为0. 05%,弹性、黏性模量和角频率的关系与Power-law方程的拟合度良好。各淀粉重组面团的弹性:大米最大,依次为红薯、土豆、豌豆、小麦、玉米和青稞淀粉重组面团。黏性与弹性的趋势类似,前3位依次是红薯、土豆和大米,其余顺序不变。流动性强弱的顺序为:青稞、土豆红薯、豌豆、小麦玉米大米淀粉重组面团。各面团的蠕变-恢复试验中,青稞的形变最大,土豆、小麦、玉米、红薯和豌豆面团次之,大米淀粉重组面团的形变最小。面团内淀粉结合的紧密程度:小麦、青稞玉米、红薯豌豆、土豆和大米淀粉重组面团。     

Effects of genetic merit and varying dietary protein degradability on lactating dairy cows

Eighty two multiparous Holstein cows were blocked by genetic merit (high vs. low) and assigned to one of two treatments [high rumen-undegradable protein (RUP): rumen-degradable protein (RDP) vs. low RUP: RDP] from d 21 before to d 150 after calving to study the effects of these treatments on production and reproductive performance. Diets were isonitrogenous (dry cow 10.5% crude protein; lactating cow 19.3%), isoenergetic (dry cow 10.0 MJ of metabolizable energy (ME); lactating cow 10.9 MJ of ME) and fed as total mixed rations. Feeding more RUP significantly increased dry matter intake and milk yield, reduced body tissue mobilization, and lowered concentrations of serum nonesterified fatty acids (NEFA) and plasma urea. Expression of estrus at first ovulation was improved, first service conception rate was higher, and calving to conception interval was shorter for the high RUP group. Cows of high genetic merit produced more milk, mobilized more body tissue, and had higher concentrations of plasma growth hormone. The dry matter intake and concentrations of blood metabolites did not significantly differ with genetic merit. Expression of estrus at first ovulation was significantly lower for cows of high genetic merit. Serum NEFA concentrations were significantly higher, and estrus was not observed at first ovulation for cows of higher genetic merit fed the low RUP diet. The interaction between dietary RUP and genetic merit was not significant for other measures of performance or fertility. Feeding a low RUP: high RDP diet had negative effects on some aspects of production and reproductive performance. The effects of diet on NEFA concentrations and estrus display were greater in cows of high genetic merit, indicating that potential interactions should be evaluated in future reproductive studies involving protein and fertility.     

转谷氨酰胺酶交联时间对玉米胚芽蛋白功能性质的影响

为解决玉米胚芽蛋白溶解性低的问题,提高其在食品工业领域的实际应用,以玉米胚芽蛋白为原料,通过酶解、转谷氨酰胺酶(TGase)交联,制备了不同交联时间的玉米胚芽蛋白,利用红外光谱仪和粒度分析仪分析玉米胚芽蛋白结构和表面性质的变化,并检测其溶解性、乳化性、起泡性等功能性质。结果表明：随着交联时间的延长,玉米胚芽蛋白的溶解性、起泡能力、持水性、乳化活性逐渐增强,乳化稳定性变化趋势与之相反,泡沫稳定性先升后降,持油性先降后升;与原样相比,交联3 h的玉米胚芽蛋白的乳化活性提高了16.7倍,持水性和持油性分别增加了9.16%和8.71%;TGase交联反应改变了玉米胚芽蛋白的二级结构,酰胺Ⅰ带的伸缩振动增强, β-转角增多,蛋白质粒径和Zeta电位发生改变,蛋白质结构和表面性质的改变造成其功能性质的变化。综合来看,交联3 h的玉米胚芽蛋白的功能性质表现最佳。     

Influence of ultrasound and enzymatic cross-linking on freeze-thaw stability and release properties of whey protein isolate hydrogel

This study investigated the effect of ultrasound and enzymatic cross-linking on the freeze-thaw (FT) stability and release properties of whey protein isolate hydrogels. We evaluated the FT stability by the changes in the microstructure, riboflavin retention, syneresis, water holding capacity (WHC), and texture of gels subjected to 3 FT cycles. High-intensity ultrasound (HUS) and transglutaminase (TGase)-mediated cross-linking improved the FT stability of whey protein isolate hydrogels loaded with riboflavin (WPISAR), as demonstrated by a more uniform and denser porous structure, significantly higher riboflavin retention, WHC, and textural properties, and lower syneresis after 3 FT cycles than those of untreated hydrogels. Furthermore, HUS- and TGase-mediated cross-linking decreased protein erosion and swelling ratio of WPISAR in simulated gastrointestinal fluids (SGIF) and reduced the riboflavin release rate in SGIF both with and without the addition of digestive enzymes. After 3 FT cycles, faster riboflavin release occurred due to a more porous structure induced by ice crystal formation compared with their unfrozen counterparts as detected by confocal laser scanning microscopy. High-intensity ultrasound- and TGase-mediated cross-linking alleviated the FT-induced faster riboflavin release rate in SGIF. High-intensity ultrasound- and TGase-treated gel samples showed that both diffusion and network erosion were responsible for riboflavin release regardless of FT. These results suggest that HUS- and TGase-mediated cross-linking improved the FT stability of WPISAR with a high riboflavin retention, and might be a good candidate as a controlled-release vehicle for riboflavin delivery to overcome undesired FT processing.     

Effects of different dairy ingredients on the rheological behaviour and stability of hot cheese emulsions

The influence of sodium caseinate (SC), butter milk powder (BMP) and their combinations on particle size, rheological properties, emulsion stability and microstructure of hot cheese emulsions made from mixtures of Cheddar and soft white cheese was studied. All emulsions exhibited shear-thinning flow behaviour and increasing SC concentration (1–4%) led to an increase in particle size and a decrease in apparent viscosity. In contrast, increasing BMP concentration caused significant decrease in particle size and slightly reduced the apparent viscosity. Stability against creaming and precipitation increased with increasing concentration of SC, whereas BMP destabilised the emulsions resulting in extensive precipitation. Confocal laser scanning microscopy images showed that SC exerted markedly better emulsification ability than BMP. Emulsions containing equal amounts of SC and BMP presented better stability against creaming and precipitation and this could be developed into a novel strategy to replace emulsifying salts in production of cheese powder.