Inulin addition to yoghurt: Prebiotic activity,health effects and sensory properties

Health and technical aspects of inulin have led to its wide applications in the food industry. Yoghurt is a cultured food with beneficial nutritional value that has advantageous effects in combination with inulin, for example reduction in fat content, improving the functions of the intestinal system and technical and textural influences. In this review, the physicochemical and health properties of inulin are described and also its use as a functional ingredient in yoghurt production is investigated. Also, the ability of inulin to increase probiotic viability and its influence on texture and flavour quality of yoghurt are discussed.     

The influence of health claims and nutritional composition on consumers’ yoghurt preferences

The use of health claims on foods with a poor nutritional composition could pose a risk of misleading some groups of consumers in their food choices. This study aimed to explore the influence of the use of claims on consumers’ preferences for yoghurts with a different nutritional composition and the influence of more and less familiar claims on food choices. The study was conducted on 371 consumers using conjoint methodology and further cluster analysis. Fruit yoghurt was used as a base product. We investigated the impact of the following product attributes on consumers’ preferences: presence/absence of a probiotic and fat metabolism claim; sugar content; and fat content. The results suggest that, while consumers generally consider the nutritional composition of yoghurt to be more important than the tested claims, some groups of consumers are more sensitive to the use of health-related statements. We observed the consumers’ generally positive preference for a familiar probiotic claim, and their negative preference for a non-familiar fat metabolism claim. Overall, these results indicate that some groups of consumers are more sensitive to the use of health-related communications and are therefore more exposed to the risk of being misled if the composition of the yoghurt they buy is in fact less favourable. It would be beneficial if nutrient profiles were introduced to limit the use of claims on foods.     

The availability of soluble oxalates in stir‐fried silver beet (Beta vulgaris var. cicla) leaves eaten with yoghurt

Silver beet (Beta vulgaris var. cicla) leaves contain oxalates, and the addition of yoghurt, a food rich in calcium, to stir‐fried leaves was investigated as a way of reducing the soluble oxalate content. Fourteen participants ingested 115 g stir‐fried silver beet leaves with or without standard yoghurt and low‐fat yoghurt, respectively. Stir‐fried silver beet leaves contained 209.1 ± 0.1 mg of total oxalates per meal fresh weight (FW) and 109.2 ± 0.1 mg of soluble oxalates per meal FW. The proportion of soluble oxalates was reduced from 52% to a mean of 30% of the total oxalates when standard yoghurt or low‐fat yoghurt was added. The mean absorption of oxalate was determined by measuring the output of oxalate in the urine over a 6‐h period following ingestion of the meals. The mean absorption of oxalate from stir‐fried silver beet leaves was 2.41%, which reduced to 1.10% and 0.89% when consumed with standard yoghurt and low‐fat yoghurt, respectively.     

Sensory memory and food texture

Memory for texture plays an important role in food expectations. After fasting overnight, subjects (41 women, 35 men, age 19–60 years) received a breakfast including breakfast drink, biscuits and yoghurt. Subsequently, they rated their hunger feelings every hour, and returned for a taste experiment in the evening. When unexpectedly confronted with five texture variations of each breakfast item, they were asked to recognise the samples they had eaten earlier. Signal detection showed that subjects could recognise the drinks and yoghurts, but not the biscuits. In a second test with newly coded samples, subjects rated liking and compared their perception of the sample with the remembered target on different attributes. Memory was not related to liking and it was poor for fat (biscuits and yoghurt), but good for thickness (drinks and yoghurt) and crispiness (biscuits). Levels of fat were not remembered as such, but showed some indirect distinctiveness in related attributes as crispiness, thickness or crumbling (biscuits) and thickness or creaminess (yoghurt).     

Explaining the liking for drinking yoghurt: The role of sensory quality,food choice motives,health concern and product information

The influence of sensory and non-sensory product characteristics and consumer-related factors, such as demographics, food choice motives, and health concern, on liking for four drinking yoghurt flavours was studied using a three-block L-partial least squares regression method. Degrees of liking for yoghurt flavours were evaluated in a consumer test (n = 162) under two conditions: blind and with full product information available. The food choice motives of the members of the consumer panel and data on their concern for food and health were collected using validated questionnaires. Food choice motives were connected to the liking. Subjects who considered natural content, ethical concern, and health as important food choice motives perceived sourer, thicker, and more genuine yoghurt flavour as more pleasant, compared to subjects who considered convenience, price, mood, and familiarity more important, evaluated sweeter and smoother yoghurt as more pleasant.     

Improved creaminess in stirred yoghurt through amylomaltase-treated starch domains

Amylomaltase-treated starch (ATS) has been described as an excellent fat-replacer in set yoghurt. Its functionality as a creaminess enhancer relates to the ability to form domains, which have melting and yielding characteristics in the mouth. This study was intended to understand the functionality of ATS in stirred yoghurt. Sensory evaluation of reduced fat stirred yoghurt samples showed that the creaminess perception of stirred yoghurt with 1.5% fat and 0.5% ATS was comparable with the reference full fat yoghurt containing 3% fat. This showed that ATS was even more effective as a creaminess enhancer in stirred yoghurt than in set yoghurt. This was related to the higher effectiveness of domain formation during storage after cooling in a dispersed system, as a result of stirring of the yoghurt gel, compared with a gelled set-yoghurt system.     

共轭亚油酸合成原料的研究进展

共轭亚油酸(Conjugated Linoleic Acid,CLA)具有抗肿瘤、减少脂肪蓄积、调节机体免疫力、抗动脉粥样硬化、调节血糖血压、预防骨质疏松等多种生理活性,已经被广泛应用于医药、食品、保健品、化妆品等领域。由于CLA天然来源较少,以亚油酸为底物人工合成制备CLA成为了人们获取CLA的主要途径。本文系统介绍了游离脂肪酸、烷烃酯、甘油酯等不同形式的亚油酸及来源广泛、价格低廉的天然油脂在CLA生产中的运用,并综述了食品发酵中CLA的合成,为优化CLA原料利用、经济高效地获取CLA提供了参考。     

Study on sterol fraction of commercial brands of milk,yoghurt and butter sold in Iranian market and chemometric data analysis

A gas chromatographic procedure for analysis of sterols was developed to detect possible addition of vegetable oils to milk, yoghurt and butter samples. The method involved fat extraction, saponification, hexane extraction, silylation of sterols and then analysis by gas chromatography. The sterol content of 102 samples of milk, yoghurt and butter was determined. Phytosterol content higher than 5% of total sterol was observed in four samples of milk and yoghurt. Principal component analysis showed that there was a direct relationship between the level of phytosterols and fat percentage in yoghurt samples. The described method is accurate and reliable enough to be employed regularly in food quality laboratories.     

市售酸奶和发酵豆奶的营养分析,评价与比较

在福州市面上销售的三种类型的酸奶与本院生产研制的发酵豆奶的主要营养成分进行分析,评价与比较,可以确定,市售酸奶和发酵豆奶是高蛋白,低脂肪且富含人体必需养成分的功能性食品。在营养价值相当的情况下,发酵有由于生产成本低,因而具有良好的开发前景。     

Structural properties of stirred yoghurt as influenced by whey proteins

The effect of whey protein addition on structural properties of stirred yoghurt systems at different protein and fat content was studied using laser diffraction spectroscopy, rheology and confocal laser scanning microscopy (CLSM). The composition of heated milk systems affected micro- and macroscopic properties of yoghurt gels. Particle size increased as a function of increasing whey protein content and decreased as a function of increased fat level. Firmness (elastic modulus) and apparent viscosity of manufactured yoghurt samples increased as a function of increased interparticle interactions, mainly caused by self-aggregation of whey proteins or aggregated whey protein-coated fat globules, respectively. The resistance towards shear-induced disruption of yoghurt gels increased with an increasing proportion of casein protein in the protein mixture, whereas products with high whey protein level revealed lower resistance behaviour towards shear-forces. CLSM images illustrated that the presence of large whey protein aggregates and lower number of fat globules lead to the formation of an interrupted and coarse gel microstructure characterised by large interstitial spaces. The higher the casein fraction and/or the fat level, the less interspaced voids in the network were observed. However, it is evident that the addition of whey proteins reinforces firmness properties of low-fat yoghurts comparable to characteristics of full-fat yoghurt.     

The effects of date syrup and guar gum on physical,rheological and sensory properties of low fat frozen yoghurt dessert

The effect of adding date syrup (0%, 25% and 50% as sugar replacement) and guar gum (0%, 0.1%, 0.2% and 0.3% as fat replacement) was examined in respect of physicochemical, rheological and sensory properties of low fat frozen yoghurt. Increasing date syrup and guar gum concentration increased the mixture viscosity and acidity. Guar gum softened the frozen yoghurt whereas date syrup increased the hardness of the product. The control yoghurt was less sticky than samples containing the gum, but date syrup had no significant effect on the samples stickiness. Melt‐down stability of the samples also increased with increase in gum and date syrup concentration. The low fat orange flavoured frozen yoghurt dessert prepared in this study also had good sensory properties.     

Characterisation of yoghurt enriched with polyunsaturated fatty acids by using walnut slurry

This study aimed to evaluate the physicochemical, chemical, rheological, sensorial and microbiological properties of yoghurt enriched with polyunsaturated fatty acids (PUFAs). The PUFA‐enriched yoghurt was prepared with walnut slurry (10%?50%) and skimmed milk (50%?90%). Compared with the control yoghurt, it contained a lower content of protein, potassium, sodium and phosphorus, and a higher content of fat, iron, magnesium and zinc. Moreover, it exhibited a lower syneresis value and a higher water‐holding capacity value. Its fat was rich in omega fatty acids, mainly linoleic and linolenic acids. These research findings revealed that walnut slurry could be used in yoghurt manufacture to develop fermented milk products as functional foods, especially when enriched with omega fatty acids.     

Acceptance of calorie-reduced yoghurt: Effects of sensory characteristics and product information

The main objective of this paper was to study acceptance of yoghurt with different levels of two specific sensory attributes, sweetness and richness, when corresponding information about sugar and fat content was given simultaneously with tasting. A conjoint design was applied to examine the effects of intrinsic attributes (sensory) and extrinsic attributes (health information) on acceptability and purchase probability for calorie-reduced vanilla yoghurt. Based on sensory profiling of 12 yoghurts produced according to an experimental design, four yoghurts varying in sweetness and richness were selected. In the conjoint study this sensory variation was combined with information concerning fat content and sugar content. 153 health conscious consumers participated in a blind testing and a conjoint study. Analyses of variance showed that sweetness and information about sugar content had significant effects on liking and purchase probability. The study showed that conjoint methodology was an appropriate tool to reveal effects of extrinsic and intrinsic product attributes.     

乳清蛋白-黄油乳液凝胶对低脂酸奶理化特性及品质的影响

乳液凝胶是一种新型的脂肪替代物,乳清蛋白和黄油是乳品中常用的原、辅料,利用乳清蛋白和黄油制作的乳液凝胶在乳制品加工中具有良好的应用前景。制备不同蛋白和脂肪含量的乳清蛋白-黄油乳液凝胶颗粒(whey protein-butter emulsion gel particles,WPI-EG),研究其对低脂酸奶理化特性及感官品质的影响,通过分析酸奶的持水力、质构、流变、微观结构及感官评价等指标,评价WPI-EG在低脂酸奶中的作用。结果表明,WPI-EG(5.5%蛋白质,7.9%脂肪)改善了酸奶的质构特性,硬度、稠度、黏聚性及胶着度显著增加,持水力增强。添加WPI-EG的实验组低脂酸奶的表观黏度显著高于对照组低脂酸奶。电镜结果显示,随着添加的WPI-EG中蛋白质和脂肪质量分数的增加,酸奶网络结构更加紧密。5.5%PR感官评价得分较高,具有较好的香气、润滑感和组织状态(酸奶中的WPI-EG添加量为10.9%)。研究显示,特定蛋白和脂肪含量的WPI-EG在酸奶中能够作为脂肪替代物和稳定剂,显著提升低脂酸奶的品质。     

Socio-economic dynamics and innovative technologies affecting health-related lipid content in diets: Implications on global food and nutrition security

The recent increase in human population coupled with rural-to-urban migration has led to challenges in managing a balanced diet in both food ‘secure’ and food ‘insecure’ regions. As a result of this geographic phenomenon, the human population continues to suffer from caloric-related conditions and diseases, including obesity and coronary heart diseases. In addition, fat and fatty acid composition of the diet has come under severe attack from the media and different human nutrition corridors in the past as they have been implicated in aiding the increase in cases of coronary heart diseases despite their important roles in cellular functions. In this view, fat and fatty acids is of great significance to the modern society, which aims at balancing their dietary proportions for efficient functionality of the human body systems. To improve food and nutrition, understanding the physiological function of the body and biochemical function of the fatty acids and polar lipids and getting a clearer view of the socio-economic aspects surrounding food consumption is also important. However, to further enhance the utilisation of fats accessed from diets, it is important to highlight significant current innovative technologies used to improve food fatty acid profiles and the influence of media on dietary and food consumption patterns. This review discusses the significance of health-related fatty acids, socio-economic aspects governing their presence in food and consumption, and how all these factors have a bearing on achieving the goal of human health, well-being and food and nutrition security.     

Homogenisation improves the microstructure,syneresis and rheological properties of buffalo yoghurt

Homogenisation is known to improve the textural properties of bovine yoghurt but the potential of this processing step has not been systematically explored for buffalo yoghurt. In this study, buffalo milk was homogenised at 80 bar or 160 bar and the effect on the properties of buffalo yoghurt examined. The microstructure of both buffalo yoghurt samples produced from homogenised milk was significantly altered, forming a more interconnected protein network with smaller embedded fat globules. These structural changes resulted in a significant decrease in syneresis and hysteresis area and led to a considerable increase in the storage modulus, gel firmness and flow behaviour index. A higher homogenisation pressure of 160 bar resulted in a lower gel firmness and storage modulus, possibly due to the presence of bigger fat–protein clusters within the homogenised milk. A homogenisation pressure of 80 bar could be optimal for improving the quality of buffalo yoghurt.     

Too good to be true: Dose insensitivity and stereotypical thinking of foods’ capacity to promote weight gain

It has been well documented that the general public holds many mistaken beliefs about foods and their roles in weight gain and health/disease. For example, foods that are perceived as bad for health (e.g., 3 slices of bacon; 109 calories) are typically judged to promote significantly more weight gain than more reputable foods (e.g., a large raisin bran muffin; 460 calories), even if the “bad” food contains far fewer calories than the “good” food. The current study was unique in that participants were provided not only names of snacks but also their caloric amounts and then asked to judge each snack’s capacity to promote weight gain. Results indicated that, despite the caloric information presented, respondents rated “bad” foods as weight promoters (compared to “good” foods) and only fat content (not energy density or fiber and sugar content) primarily predicted which foods would be judged to promote weight gain. It appears that “high fat” may be a synonymous with “bad” for many people or that dietary fat is perceived to have a far greater impact on body weight than is justified by the nutrient’s caloric content. In either case, it appears that a potentially harmful message has been assimilated by the general public.     

Production and evaluation of some physicochemical parameters of peanut milk yoghurt

The peanut milk for yoghurt production was prepared by fortifying peanut milk (∼12 g/100 g total solids) with 4 g/100 g skimmed milk powder. The final product was subjected to physicochemical analysis using cow milk yoghurt (CMY) as a control throughout the study. Peanut milk yoghurt (PMY) had higher protein content, fat, water holding capacity and lower susceptibility to Syneresis than CMY. PMY had lower lactose level (1.73 g/100 ml) compared to CMY (4.93 g/100 ml). Generally both PMY and CMY had high mineral composition and contained high amounts of essential amino acids. PMY also contained a higher proportion of unsaturated fatty acids than saturated fatty acids as compared to CMY. Therefore, in terms of fatty acid composition, PMY could be considered to be more health promoting than CMY. Sensory evaluation revealed that though PMY had better sensory texture scores than CMY, its sensory appearance, flavor and overall acceptability scores were lower than those of CMY.     

高蛋白无脂肪酸奶的研制

以凝胶型乳清浓缩蛋白80、微粒化乳清蛋白和淀粉脂肪替代物的组合作为脂肪替代品用于替代酸奶中的脂肪,得到了3种配料的最优比例,从而从质构、口感、风味角度成功模拟了酸奶中脂肪的作用,成功开发出一款高蛋白、零脂肪的健康酸奶。     

Carbohydrate-based fat replacers in the modification of the rheological, textural and sensory quality of yoghurt: comparative study of the utilisation of barley beta-glucan, guar gum and inulin

Barley beta‐glucan, partially hydrolysed guar gum and inulin were used in the processing of low‐fat yoghurts. The possible beneficial effects of carbohydrate fat replacers on the rheological, textural and sensory quality of low‐fat yoghurt‐based products were determined. Comparisons were made between the sample yoghurts made from a low‐fat milk base, and full‐fat and low‐fat yoghurt controls. The inclusion of the carbohydrate components reduced product syneresis and improved the texture and rheological properties of the low‐fat‐based products so that their quality characteristics were similar to yoghurt made with full‐fat milk. Both the type and also the amount of carbohydrate component altered product characteristics. Beta‐glucan addition at low level (0.5%) was effective in improving serum retention of the yoghurt and its viscoelastic nature (G′, G′ and tan δ). In contrast, higher levels (above 2%) of inulin and guar gum were needed to exert significant improvements in the textural characteristics of yoghurt. Sensory analysis conducted on the samples illustrated that the inclusion of carbohydrate‐based fat replacers could be successfully utilised to mimic full‐fat products.