Ferrous bisglycinate content and release in W1/O/W2 multiple emulsions stabilized by protein–polysaccharide complexes

Ferrous bisglycinate aqueous solution was entrapped in the inner phase (W₁) of water-in-oil-in-water (W₁/O/W₂) multiple emulsions. The primary ferrous bisglycinate aqueous solution-in-mineral oil (W₁/O) emulsion contained 15% (w/w) ferrous bisglycinate, had a dispersed phase mass fraction of 0.5, and was stabilized with a mixture of Grindsted PGPR 90:Panodan SDK (6:4 ratio) with a total emulsifiers concentration of 5% (w/w). This primary emulsion was re-emulsified in order to prepare W₁/O/W₂ multiple emulsions, with a dispersed mass fraction of 0.2, and stabilized using protein (whey protein concentrate (WPC)):polysaccharide (gum arabic (GA) or mesquite gum (MG) or low methoxyl pectin (LMP)) complexes (2:1 ratio) in the W₂ aqueous phase. The W₁/O/W₂ multiple emulsion stabilized with WPC:MG (5% w/w total biopolymers concentration) provided smaller droplet sizes (2.05 μm), lower rate of droplet coalescence (7.09 × 10⁻⁷ s⁻¹), better protection against ferrous bisglycinate oxidation (29.75% Fe³⁺) and slower rate of ferrous bisglycinate release from W₁ to W₂ (K_H = 0.69 mg mL⁻¹ min^−0.5 in the first 24 h and 0.07 mg mL⁻¹ min^−0.5 for the next 19 days of storage time). Better encapsulation efficiencies, enhanced protection against oxidation and slower release rates of ferrous bisglycinate were achieved as the molecular weight of the polysaccharide making up protein:polysaccharide complex was higher. Thus, the factor that probably affected most the overall functionality of multiple emulsions was the thickness of the complex adsorbed around the multiple emulsion oil droplets. These thicknesses determined indirectly by measuring the z-average diameter of the complexes, and that of the WPC:MG (529.4 nm) was the largest.     

负载姜黄素/花色苷的木薯淀粉基W1/O/W2型Pickering双重乳液的制备及性质

以木薯纳米淀粉、木薯醋酸酯变性淀粉为颗粒乳化剂制备食品级W₁/O/W₂型Pickering双重乳液,分别于内层水相、油相对姜黄素与花色苷进行负载。考察不同木薯醋酸酯变性淀粉质量分数对双重乳液显微形态、粒径、Zeta电位、负载率及贮藏稳定性的影响,并分析其在体外消化过程的控释性能。结果表明,木薯醋酸酯变性淀粉质量分数为6%时,乳液综合性能最好。此时,乳滴分布均匀,呈“三相两膜”结构,粒径为3.65μm,Zeta电位为-14.50mV,姜黄素、花色苷的负载率达到95.23%、93.00%,4、25、40℃时贮藏20d均未出现明显分层;经模拟消化后乳液中姜黄素、花色苷保留率为41.59%、76.29%,与游离姜黄素、花色苷相比,二者生物利用率分别提高了约4倍、3倍。证实了木薯淀粉基双重乳液能实现在模拟消化系统中对活性物质的保护,并能有效提升其生物利用率。研究结果旨在为食品工业中淀粉基功能性乳液运载体系的构建及新型食品级Pickering双重乳液的开发提供理论参考。     

The relationship of textural characteristics with composition of sandesh produced from various market milk classes

The texture of sandesh an Indian milk‐based sweetmeat, was characterised by instrumental means and interrelationships among textural parameters and composition were studied. Hardness, fracturability, chewiness and adhesiveness was highest for sandesh prepared from milk containing 6% fat, 9% SNF and lowest for sandesh prepared from milk containing 1.5% fat, 9% SNF. Hardness of sandesh was significantly positively (P < 0.01) correlated with the fat content but negatively (P < 0.01) correlated with moisture and ash. Moisture and fat had negative and positive correlation (P < 0.01) with fracturability, respectively. Ash and moisture had a positive (P < 0.01) influence on resilience whereas fat had a negative influence. Cohesiveness was not influenced by composition parameters. Springiness had positive and negative correlation (P < 0.05) with fat and moisture, respectively. Gumminess followed similar pattern to that of hardness. Moisture and fat had negative and positive effect respectively (P < 0.01) on adhesiveness. Chewiness was negatively and positively influenced (P < 0.01) by moisture and fat of sandesh, respectively.     

Reduced-fat white fresh cheese-like products obtained from W1/O/W2 multiple emulsions: Viscoelastic and high-resolution image analyses

This paper focuses on the study of the rheological and structural changes of reduced fat cheeses (EC) obtained by substituting milk-fat by multiple emulsions (W₁/O/W₂) stabilized with different hydrocolloids in comparison to a full-fat white fresh cheese (WFC). Amidated low-methoxyl pectin, carboxymethylcellulose (CMC), gum Arabic (GA), and blends of these hydrocolloids were used as emulsion stabilizing agents. Cheeses storage (G′) and loss (G″) moduli as a function of strain % were determined and the ratio of tan δ in the non-lineal viscoelastic region (tan δ_B) to that in the lineal viscoelastic region (tan δ_A) was obtained. The EC cheeses made from W₁/O/W₂ emulsions with GA (EC_GA) and CMC (EC_CMC) exhibited non-significantly different tan δ_B/tan δ_A ratio values from that of WFC cheese. Scanning electron micrographs (SEM) showed that all the cheeses exhibited different surface microstructure. Detrended fluctuation analysis (DFA) of SEM micrographs indicated that all cheeses structure displayed a hierarchical configuration, from well-ordered particles in the small scale range to randomly dispersed particles in the high scale range. The EC_GA and EC_CMC cheeses also showed similar particle distribution over the particle size range of 20–60 μm to that of the WFC cheese.     

Physicochemical,textural and sensory properties of white soft cheese made from buffalo and cow milk mixtures

The physicochemical, textural and sensory properties of white soft cheeses made from three different buffalo and cow milk mixtures (100:0, 70:30 and 30:70) during 3‐month storage were studied. The increase in buffalo milk concentration resulted in increasing total cheese yield, dry matter (DM) and fat retention and fat in DM content. However, it caused reductions in moisture content, salt intake, hardness, chewiness, elasticity, sensory hardness and sensory cohesiveness of the samples. The percentage of water‐soluble nitrogen to total nitrogen increased during storage resulting in decreased fracturability, hardness (textural and sensory), cohesiveness (textural and sensory), springiness, chewiness and elasticity. The panellists evaluated the white soft cheese made with buffalo milk as the most acceptable.     

Effect of Maillard reaction products derived from the hydrolysate of mechanically deboned chicken residue on the antioxidant,textural and sensory properties of Cantonese sausages

Protein hydrolysates as precursors of Maillard reaction were obtained via enzymatic hydrolysis of mechanically deboned chicken residue (MDCR). The Maillard reaction products (MRPs) were prepared at 90 (M1), 100 (M2), 110 (M3) and 120 °C (M4), respectively. MRPs possessed a strong reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. According to the evolution of total free fatty acids and peroxide value of Cantonese sausage with MRPs during storage, M1 and M3 had a potent antioxidant activity (P < 0.05) due to their antioxidant abilities and inhibitory action against lipolytic enzymes. Cantonese sausages treated with M1 and M2 showed good textural and sensory properties. However, M3 and M4 had a negative (P < 0.05) effect on the flavour and texture of Cantonese sausages compared to control. The results suggested that M1 was very potential to be used to improve their antioxidant, textural and sensory quality.     

The effect of storage on nutritional,textural and sensory characteristics of creamy ricotta made from whey as well as cow's milk and goat's milk

The aim of this study was to develop a creamy ricotta using a mixture of goat and cow whey as the main ingredients, with the addition of whole goat and cow milk. The nutritional composition, texture and sensory characteristics of the ricotta cheese were evaluated over 14 days of refrigerated storage. There was a decrease in protein and ash content and pH changes during the assessed storage periods. The instrumental texture profile indicated that the creamy ricotta was easily deformable, with minimal inelasticity and a cohesive, soft and delicate texture. The medium‐ and long‐chain fatty acid content was higher than the short‐chain fatty acid content. The flavour and aroma of creamy ricotta were described by the panel as having a soft texture and wet appearance. The use of whey from goat and cow cheese in making creamy ricotta is feasible and does not cause negative impact in the final product.     

Detection of aflatoxin M1 in milk and dairy products consumed in Adana, Turkey

A total of 70 dairy products consisting of 20 sterilized milk, 10 butter, 20 white cheese and 20 Kashar cheese samples were analysed for aflatoxin M₁ (AFM₁) by enzyme-linked immunosorbent assay (ELISA). The detection limit was 5 ng/L for milk and 25 ng/kg for butter, white cheese and Kashar cheese. Of the 70 dairy products analysed, AFM₁ in 49 samples (70%) was found to range from 10 to 388 ng/kg. Moreover, AFM₁ levels in three samples of milk, two samples of butter, one sample of white cheese and one sample of Kashar cheese were found to be higher than the Turkish legal limits.     

Double emulsions (W/O/W): physical characteristics and perceived intensity of salty taste

This study addressed the correlation between physical characteristics of double emulsions and sensory perception, as the microstructure of these systems may provide the mechanism to understanding the initial cause of the altered salty taste. Thus, double emulsions (W/O/W) were prepared using different volumes of the internal aqueous phase while maintaining the same fat and sodium contents in the evaluated systems. Polyglycerol polyricinoleate (PGPR) and tween 80 were used as hydrophobic and hydrophilic emulsifiers, respectively. After preparation, the samples were stored at 25 °C for 4 days and submitted to analysis of optical microscopy, distribution and polydispersity of the oil droplets size, electrical conductivity, rheological behaviour and sensorial analysis. It was found that the use of different emulsifier concentrations (PGPR) did not influence the physical characteristics of the emulsions with the same formulation, but emulsions with different internal aqueous phase concentrations presented different results. These distinct characteristics may have influenced sensorial perception, as the emulsion with higher internal phase concentration was considered saltier. Thus, it can be concluded that structural differences of the double emulsions can be used to decrease the sodium contents without perceivable changes in salty taste.     

Changes in textural, microstructural, and colour characteristics during ripening of cheeses made from raw, pasteurized or high-pressure-treated goats’ milk

Goats’ milk cheeses were made from raw (RA), pasteurized (PA; 72°C, 15 s) or pressure-treated (PR; 500 MPa, 15 min, 20°C) milk to compare textural, microstructural, and colour characteristics in relation to ripening time. Texture, microstructure and colour were evaluated by uniaxial compression and stress relaxation tests, confocal laser scanning microscopy and Hunter colorimetry, respectively.Raw and PR cheeses were firmer and less fracturable than PA cheese, but differences became less notable toward the end of ripening. PA and PR cheeses were less cohesive than RA cheese. Although cheeses exhibited a loss of elastic characteristics with ageing, PR cheese showed the most elastic behaviour initially. Confocal laser scanning micrographs displayed PR cheese with a regular and compact protein matrix, with small and uniform fat globules resembling the structure of RA cheese. Finally, colour evaluation demonstrated significant differences between cheeses due to milk treatments and ripening time.     

免疫亲和层析净化-高效液相色谱法同时测定牛奶和奶粉中黄曲霉毒素B1、B2、G1、G2、M1、M2

建立牛奶和奶粉中黄曲霉毒素B1、B2、G1、G2、M1、M2的免疫亲和层析净化和柱后衍生高效液相色谱测定方法。样品经溶解、离心、过滤后,通过免疫亲和柱,黄曲霉毒素特异性抗体选择性地与存在的黄曲霉毒素抗原键合,形成抗体-抗原复合体。甲醇-乙腈混合溶液(4:5,v:v)洗脱,带荧光检测器的高效液相色谱仪经柱后衍生测定,外标法定量。标准曲线线性良好,添加回收率在57.0%～88.7%,相对标准偏差在3.37%～16.9%,牛奶中各黄曲霉毒素检出限:B1为2ng/kg,B2为1ng/kg,G1、G2为3ng/kg,M1、M2为5ng/kg;奶粉中B1为20ng/kg,B2为10ng/kg,G1、G2为30ng/kg,M1、M2为50ng/kg,检测低限能够满足各国对牛奶和奶粉中黄曲霉毒素的限量要求。该方法准确、快速、灵敏度高,适用于牛奶和奶粉中黄曲霉毒素的测定。     

Technologically important characteristics of Enterococcus isolates from milk and dairy products

Enterococcus faecium (54 strains), E. faecalis (40 strains), and E. durans (14) were isolated from various dairy products (raw milk, cream, butter and fermented milk products) during a previous study (Wessels et al., 1988). In this article various characteristics of these isolates, which may have a bearing on their significance in dairy products, have been studied. A large percentage of the identified strains of all three species were able to grow at 7°C. Seventy-six percent of the E. faecium strains, 62% E. faecalis and 50% E. durans strains also showed proteolytic activity at psychrotrophic temperatures. The fact that proteolytic activity could be detected within 2 days at 7°C is significant, since bulk cooled milk is normally held for 3 to 4 days at temperatures between 4 and 7°C at farms or factories prior to processing. This examination confirmed that enterococci are proteolytic rather than lipolytic.     

An ultra-sensitive monoclonal antibody-based competitive enzyme immunoassay for aflatoxin M1 in milk and infant milk products

A sensitive and specific monoclonal antibody (Mab) against aflatoxin M₁ (AFM₁), named as 2C9, was selected by semi-solid HAT medium. It exhibited high affinity for AFM₁ of 1.74 × 10⁹ L/mol and no cross-reactivity to aflatoxin B₁, B₂, G₁ and G₂. Based on the antibody, an ultra-sensitive competitive enzyme-linked immunosorbent assay (ELISA) was developed for AFM₁ in milk and infant milk products. Assays were performed in the AFM₁-BSA coated (0.0625 μg/mL) ELISA format in which the antibody was diluted 1:10,000. Several physicochemical factors (pH, ionic strength and blocking solution) that influence assay performance were optimised. Finally, the limits of detection were 3 ng/L for milk and 6 ng/L for milk-based cereal weaning food, inter-assay and intra-assay variations were less than 10%, and the recovery ranged from 91% to 110%. Thirty samples were analysed, and concordant results were obtained when the data were compared with a reference high-performance liquid chromatography method.     

免疫初乳中IgG1和IgG2的分离纯化

采用硫酸胺盐析,DE－52离子交换色谱,SephacryIS-100凝胶过滤色谱从免疫初乳分离纯化出了IgG1和IgG2,经SDS－PAGE电泳及免疫电泳证实为纯品,并对IgG1和IgG2的抗体凝集价进行了测定。     

Evaluation and Improvement of Extraction Methods for the Analysis of Aflatoxins B1, B2, G1 and G2 from Naturally Contaminated Maize

The extraction procedure for aflatoxin determination in maize is based on a methanol–water (8 + 2 v/v) or an acetone–water (85 + 15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Different results were obtained for highly contaminated maize: significantly higher levels of aflatoxin B₁ were obtained by acetone–water, on the contrary higher levels of aflatoxin G₂ were achieved by methanol–water. Then, acetone–water mixtures in different proportions (7 + 3, 6 + 4 and 5 + 5 v/v) were tested to improve the extraction of aflatoxin G₂. Applying these extraction mixtures, the values both of aflatoxin B₁ and of other aflatoxins were generally higher compared to those obtained by acetone–water 85 + 15; moreover, acetone–water (6 + 4) and (7 + 3) showed the best extraction efficiency for all aflatoxins.     

乳及乳制品中黄曲霉毒素M1污染及检测技术研究进展

乳及乳制品中的黄曲霉毒素M_1是黄曲霉毒素B1的羟基化衍生物,对肝脏有致畸和致癌作用。随着人们生活水平的提高,乳及乳制品中黄曲霉毒素M_1污染也引起越来越多的关注。本文从不同品种、季节及地域分析乳及乳制品中黄曲霉毒素M_1污染水平,并综述了液相色谱法和免疫法的检测技术研究进展。     

Impact of amylose from maize starch on the microstructure,rheology and lipolysis of W/O emulsions during simulated semi-dynamic gastrointestinal digestion

This study aims to examine the microstructure, rheology and lipolysis of water-in-oil (W/O) emulsions (40 wt.%) prepared with or without (Control) the addition of normal (NAM) and high amylose (HAM) maize starch during simulated digestion in a semi-dynamic gastrointestinal tract (GIT) model. Microstructural examinations showed modification in initial W/O emulsion droplets to multiple W₁/O/W₂ droplets during in vitro digestion. This is in line with the rheological results, where the shear viscosity and moduli in the oral phase were remarkably reduced after entering the intestinal phase. In comparison to control and NAM emulsions, HAM emulsions showed a more compact and continuous network structure and greater viscosity and elastic modulus throughout GIT digestion. These results support lipolysis, where fewer free fatty acids were released in the HAM emulsion (70%) than in the control (86%) and NAM (78%) emulsions. This work has provided an in-depth understanding of the digestion of W/O emulsions as influenced by amylose content, which is meaningful for the development of low-fat products with reduced lipid digestibility.     

Dynamic supercritical CO2 extraction for removal of cholesterol from anhydrous milk fat

The feasibility of different extraction techniques for the selective removal of cholesterol from anhydrous milk fat (AMF) by supercritical carbon dioxide has been studied. A dynamic extraction system was used to determine both the experimental solubility of anhydrous milk fat in the supercritical solvent and the selectivity of cholesterol over anhydrous milk fat at 40–70°C and 8–40MPa at various stages during extraction. In addition, adsorbents were used for the selective removal of cholesterol from anhydrous milk fat. The results indicate that a direct extraction alone or with several separators in series are not practical, but a selective removal of 97% of the cholesterol from the extracted anhydrous milk fat is possible by using an adsorbent with recovery of solvent and cholesterol. A schematic industrial countercurrent process for the removal of cholesterol and the fractionation of milk fat is proposed.     

甜杏仁的超临界CO2萃取及产物分析

以新疆产甜杏仁为原料,采用超临界CO₂萃取技术进行萃取并对所得产物杏仁油的理化指标与脂肪酸组成,以及杏仁粉中微量元素与氨基酸组成进行了分析测定。结果表明：在萃取温度45℃,萃取压力33 MPa,萃取时间5.5 h,分离温度48℃的条件下,杏仁油得率为46.44%;杏仁油中富含油酸（70.98%）和亚油酸（22.93%）,不饱和脂肪酸含量达到93.96%;杏仁粉中含有丰富的蛋白质和微量元素,其中蛋白质含量为50.66%,钙含量为2 655 mg/kg,镁含量为3 995 mg/kg,铁含量为127 mg/kg,锌含量为116.5 mg/kg,锰含量为6.24 mg/kg;杏仁粉蛋白质中谷氨酸含量最高,为11.00%。