Investigation of the potential for using inulin HPX as a fat replacer in yoghurt production

In this study yoghurts produced from full-fat milk (3.2%) and from low-fat milk (0.5%), with 0.7% and 2.7% added inulin, were compared. Inulin addition did not influence bacterial counts and acidity. Yoghurt from full-fat milk showed the highest values of apparent viscosity, followed by yoghurt with 2.7% of inulin. The sensory properties of the yoghurts differed mainly in terms of texture and taste. The highest scores were gained by yoghurt from full-fat milk, but yoghurt with 2.7% of inulin received only slightly lower scores. The results indicate that inulin has potential as a fat replacer in yoghurt.     

Effect of microfluidization of heat-treated milk on rheology and sensory properties of reduced fat yoghurt

The effects of microfluidization at 150 MPa (MFz) and conventional homogenization at 20/5 MPa (CH) of heat-treated milk on the rheology and sensory properties of non- (0.1%) and low- (1.5%) fat stirred yoghurts were compared. Homogenization conditions clearly affected the sensory properties of reduced-fat yoghurts, but the effect was highly dependent on fat content. MFz of heat-treated milk yielded products with very different sensory profiles from the conventional yoghurts. For non-fat yoghurts, MFz of heat-treated milk enhanced the perception of buttermilk and soft cheese flavours, and natural yoghurt aroma and flavour, but also increased the intensity of undesirable mouthfeel characteristics such as chalkiness, mouth-dryness and astringency. For low-fat yoghurts, MFz significantly improved creaminess and desirable texture characteristics such as smoothness, cohesiveness, thickness, and oral and spoon viscosity. These differences in sensory profiles, especially textural properties, were partially related to rheological properties, particularly flow behaviour. MFz of heat-treated milk resulted in non- and low-fat yoghurts with higher yield stress, more pronounced hysteresis effect and higher viscosity than those of CH yoghurts of similar fat contents. These findings suggest that microfluidization may have applications for production of high-quality yoghurt with reduced-fat content.     

Modifying the microstructure of low-fat yoghurt by microfluidisation of milk at different pressures to enhance rheological and sensory properties

The effects of microfluidisation of milk at different pressures, prior to heat treatment, on structural and sensory properties of low-fat stirred yoghurt, were investigated. Low-fat yoghurts prepared from microfluidised milk were compared with low-fat (1.5%) and full-fat (3.5%) control yoghurts made with homogenised (20/5 MPa) milk. The microstructure of low-fat yoghurts prepared with microfluidised milk consisted of smaller and more uniform fat globules, well incorporated into more interconnected fat-protein gel networks, compared with those of control yoghurts. This modification in microstructure caused significant changes in gel particle size, sensory profile and rheological behaviour. Microfluidisation increased the gel particle size, gel strength and viscosity; marked beneficial effects were found at higher pressures (50–150 MPa). Microfluidising milk at 50–150 MPa increased the gel strength by 171–195% and viscosity by 98–103%, creating low-fat yoghurts with creaminess and desirable texture properties similar to, or better than, full-fat conventional yoghurt.     

Effects of poly‐γ‐glutamic acid on the physicochemical characteristics of skim milk yoghurt

The physicochemical and sensory properties of skim milk yoghurts containing poly‐γ‐glutamic acid (PGA) at different levels (0.0025, 0.005 and 0.01%) were evaluated. Addition of PGA up to 0.01% to reconstituted skim milk (11%, w/v) did not affect the growth of lactic acid bacteria or the development of titratable acidity in yoghurt, whereas full‐fat control yoghurt had reduced acid production. No changes were found in viable cell counts of PGA yoghurts during storage (4 weeks at 4 °C). The addition of PGA (0.005%) significantly decreased syneresis in skim milk yoghurt and did not cause any undesirable effects in sensory acceptability.     

The effect of using a whey protein fat replacer on textural and sensory characteristics of low-fat vanilla ice cream

The purpose of this research was to evaluate the texture of regular (12%), low fat (6%), and fat-free vanilla (0.5%) ice creams by sensory and instrumental analyses. The low fat and fat free ice cream were prepared using a whey protein based fat replacer (Simplesse ^® 100) as the fat replacement ingredient. Two processing trials with continuous commercial-like process conditions were undertaken. Sensory analyses disclosed that ice creams containing 6% of fat replacer in place of or with milk fat had no demonstrable effect on vanillin flavour. While the sensory attributes of the low fat samples were comparable to the regular vanilla ice cream, the trained sensory panel rated the fat free ice cream to have lower viscosity, smoothness and mouth coating properties. Instrumentally determined apparent viscosity data supported the sensory data. Compared with the fat replacer, milk fat significantly increased the fresh milk and cream flavours of the ice cream. Results emphasized the importance of fat as a flavour modifier and the improvement of texture by addition of Simplesse ^® 100.     

Rheological and sensory properties of stirred yoghurt with inulin‐type fructans

This study concerns physicochemical and sensory analysis of stirred yoghurts, in which skim milk powder was partly replaced by different inulins. The composition of basic solutions contained 12% skim milk powder and 4% inulin, while reference yoghurts contained 16% SMP or whole milk powder. Rheological and sensory analysis showed that one‐quarter of milk powder could be substituted by long‐chain inulin in low‐fat stirred yoghurt. Short‐chain inulin and oligofructose can potentially be applied in the production of drinking yoghurt. Sensory evaluation showed that milk fat cannot be successfully substituted by inulin.     

Effect of fat content on the physical properties and consumer acceptability of vanilla ice cream

Ice cream is a complex food matrix that contains multiple physical phases. Removal of 1 ingredient may affect not only its physical properties but also multiple sensory characteristics that may or may not be important to consumers. Fat not only contributes to texture, mouth feel, and flavor, but also serves as a structural element. We evaluated the effect of replacing fat with maltodextrin (MD) on select physical properties of ice cream and on consumer acceptability. Vanilla ice creams were formulated to contain 6, 8, 10, 12, and 14% fat, and the difference was made up with 8, 6, 4, 2, and 0% maltodextrin, respectively, to balance the mix. Physical characterization included measurements of overrun, apparent viscosity, fat particle size, fat destabilization, hardness, and melting rate. A series of sensory tests were conducted to measure liking and the intensity of various attributes. Tests were also conducted after 19 weeks of storage at −18°C to assess changes in acceptance due to prolonged storage at unfavorable temperatures. Then, discrimination tests were performed to determine which differences in fat content were detectable by consumers. Mix viscosity decreased with increasing fat content and decreasing maltodextrin content. Fat particle size and fat destabilization significantly increased with increasing fat content. However, acceptability did not differ significantly across the samples for fresh or stored ice cream. Following storage, ice creams with 6, 12, and 14% fat did not differ in acceptability compared with fresh ice cream. However, the 8% fat, 6% MD and 10% fat, 4% MD ice creams showed a significant drop in acceptance after storage relative to fresh ice cream at the same fat content. Consumers were unable to detect a difference of 2 percentage points in fat level between 6 and 12% fat. They were able to detect a difference of 4 percentage points for ice creams with 6% versus 10%, but not for those with 8% versus 12% fat. Removing fat and replacing it with maltodextrin caused minimal changes in physical properties in ice cream and mix and did not change consumer acceptability for either fresh or stored ice cream.     

凝固型绵羊奶酸奶的发酵特性及活菌数变化

研究凝固型的绵羊奶与牛奶酸奶发酵特性和贮存期特性,利用pH计、酸度滴定、质构仪、电子舌、活菌计数及感官评价对其pH值、滴定酸度、质构特性、味觉特点、活菌数和感官评分进行分析。结果表明：在发酵过程中绵羊奶与牛奶有相同的pH值变化规律,即前2.5 h下降非常缓慢,之后迅速下降,在凝乳前0.5 h下降变缓直到凝乳结束,达到发酵终点的时间分别为5 h和4.5 h;在4 ℃贮存0～24 d期间,酸奶的pH值都在逐渐下降,牛奶酸奶比绵羊奶酸奶下降更大;滴定酸度方面起始时绵羊奶比牛奶高,达到发酵终点时也明显高于牛奶;质构测定结果为YSM（添加益生菌干酪-张发酵的凝固型绵羊奶酸奶）、JDM（嗜热链球菌与保加利亚乳杆菌共同发酵的经典凝固型绵羊奶酸奶）具有更高的硬度和稠度,黏聚性和黏性指数也显著高于JDN（嗜热链球菌与保加利亚乳杆菌共同发酵的经典凝固型牛奶酸奶）,奶的种类为影响酸奶硬度、稠度、黏聚性和黏性指数的主要因素,益生菌干酪-张的添加对这些指标的影响很小;电子舌测定结果为丰富性味感值绵羊奶酸奶明显高于牛奶酸奶,酸感值则低于牛奶酸奶,甜、苦、咸、涩、鲜感值差异不明显;感官评价方面绵羊奶酸奶综合评分高于牛奶酸奶,差异性主要体现在滋味、组织状态和喜爱程度上,在色泽和气味方差异不明显;在4 ℃、21 d贮存期间酸奶的活菌数都在逐渐降低,添加益生菌干酪-张的绵羊奶酸奶活菌数最多,第21天时活菌数分别是普通绵羊奶酸奶和牛奶酸奶的10 倍和100 倍以上,干酪-张对绵羊奶酸奶4 ℃贮存期间活菌数的维持有较好作用。同时,实验结果表明：益生菌干酪-张可以作为发酵剂之一与经典的酸奶发酵剂嗜热链球菌和保加利亚乳杆菌搭配用于凝固型绵羊奶酸奶的制作,以增加其功能价值。     

添加豆浆对牦牛酸奶品质的影响

将不同添加量（0、20%、40%、60%）豆浆添加到牦牛乳中制备豆浆-牦牛酸奶,探讨不同添加量豆浆对牦牛酸奶理化指标、贮藏期内酸度、质构特性（硬度、稠度、黏聚性与黏性指数）、持水力、乳酸菌数和感官特性的影响。结果表明,在贮藏期内（1～14 d）,随着豆浆添加量在0～60%范围内增加,牦牛酸奶酸度、持水力、质构特性、乳酸菌数均有所下降。添加20%豆浆制备的牦牛酸奶蛋白质、脂肪及非脂乳固体含量分别为3.28 g/100 g、4.58 g/100 g、8.76 g/100 g,乳酸菌数＞107 CFU/mL,感官评分为87.9分,其酸度、持水力、质构、乳酸菌数等与未添加豆浆的对照相比均无显著差异（P＞0.05）。因此,在牦牛乳中添加20%的豆浆制备豆浆-牦牛酸奶是可行的,可进一步推广应用。     

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.     

Effect of different levels of pine honey addition on physicochemical,microbiological and sensory properties of set‐type yoghurt

In this study, the effects of different levels of pine honey addition (3%, 5% and 7% w/v) to the yoghurt milk on starter bacteria, physicochemical and sensory characteristics of set‐type yoghurts during the storage were investigated. Antioxidant activity and total phenolic content of yoghurts with added honey increased compared to control yoghurt. There was a significant increase in water‐holding capacity (WHC), viscosity, total solids, redness (a*) and yellowness (b*) values of the yoghurt samples with the addition of honey at higher concentrations, whereas water activity (aw), pH and luminosity (L*) values decreased. Viscosity and WHC of the yoghurts increased during the storage.     

The development of a goat's milk yogurt

This study sought to establish conditions suitable for a small‐scale yogurt process using goat's milk and to examine the physicochemical properties (pH, titratable acidity, solids‐not‐fat (SNF), viscosity, texture) and organoleptic acceptability (preference by Filipino panellists) of the resultant product. Goat's milk was concentrated by heating (80 °C, 1 h), which resulted in an increase in SNF from 85 to 110 g kg^?1. To further improve the curd of goat's milk yogurt, two hydrocolloids were used: carrageenan (1.5 and 3 g l^?1) and pectin (50 g l^?1). The addition of dehydrated pineapple and banana cubes (50 and 100 g l^?1) in a sundae‐style formulation increased the SNF by an additional 2.5% and produced a curd that was firmer than the control, plain set yogurt. The use of carrageenan appeared to be a convenient way of controlling product viscosity. In terms of product preference and firmness the fruit‐flavoured sundae‐style yogurts were ranked higher by sensory panellists. Copyright © 2005 Society of Chemical Industry     

Application of whey protein emulsion gel microparticles as fat replacers in low-fat yogurt: Applicability of vegetable oil as the oil phase

Low-fat, healthy yogurt is becoming increasingly favored by consumers. In the present study, whey protein emulsion gel microparticles were used to improve the quality of low-fat yogurt, and the effects of vegetable oil emulsion gel as a fat substitute on the qualities of low-fat yogurt were investigated, expecting to obtain healthier and even more excellent quality low-fat yogurt by applying a new method. First, emulsion gel microparticles were prepared, and then particle size distribution of emulsion gel and water holding capacity (WHC), textural properties, rheological properties, microstructure, storage stability, and sensory evaluation of yogurt were carried out. The results showed that yogurt with emulsion gel had significantly superior qualities than yogurt made with skim milk powder, with better WHC, textural properties, rheological properties, and storage stability. The average particle size of whey protein-vegetable oil emulsion gel microparticles was significantly larger than that of whey protein-milk fat emulsion gel microparticles, and the larger particle size affected the structural stability of yogurt. The WHC of yogurt made with whey protein-vegetable oil emulsion gel microparticles (V-EY) was lower (40.41%) than that of yogurt made with whey protein-milk fat emulsion gel microparticles (M-EY; 42.81%), and the texture results also showed that the hardness, consistency, and viscosity index of V-EY were inferior to these of M-EY, whereas no significant differences were found in the cohesiveness. Interestingly, the microstructure of V-EY was relatively flatter, with more and finer network branching. The whey separation between V-EY and M-EY also did not show significant differences during the 14 d of storage. Compared with yogurt made with whey protein, vegetable oil, and skim milk powder, the structure of V-EY remained relatively stable and had no cracks after 14 d of storage. The sensory evaluation results found that the total score of V-EY (62) was only lower than M-EY (65) and significantly higher than that of yogurt made with skim milk powder. The emulsion gel addition improved the sensory qualities of yogurt. Whey protein emulsion gel microparticles prepared from vegetable oil can be applied to low-fat yogurt to replace fat and improve texture and sensory defects associated with fat reduction.     

The effects of carob juice concentrates on the properties of yoghurt

Plain and fruit-flavoured yoghurts were made by adding 2.5, 5.0, 7.5, 10.0 mL carob juice concentrate (CJC) portions to 100 mL milk. The titratable acidity, pH, viscosity, whey separation, yoghurt organisms and sensory properties were determined weekly over a period of 4 weeks. Addition of CJC caused an increase in the fermentation time and reduced viscosity and viable organisms, while increasing the pH and whey separation of the yoghurts ( P <  0.05). A lack of sweetness was the main criticism of the yoghurts with 2.5 and 5.0 mL CJC, while those with 7.5 or 10.0 mL were mostly preferred by sensory panellists.     

Effect of zinc fortification on Cheddar cheese quality

Zinc-fortified Cheddar cheese containing 228 mg of zinc/kg of cheese was manufactured from milk that had 16 mg/kg food-grade zinc sulfate added. Cheeses were aged for 2 mo. Culture activity during cheese making and ripening, and compositional, chemical, texture, and sensory characteristics were compared with control cheese with no zinc sulfate added to the cheese milk. Compositional analysis included fat, protein, ash, moisture, zinc, and calcium determinations. The thiobarbituric acid (TBA) assay was conducted to determine lipid oxidation during aging. Texture was analyzed by a texture analyzer. An untrained consumer panel of 60 subjects evaluated the cheeses for hardness, off-flavors, appearance, and overall preference using a 9-point hedonic scale. Almost 100% of the zinc added to cheese milk was recovered in the zinc-fortified cheese. Zinc-fortified Cheddar cheese had 5 times more zinc compared with control cheese. Zinc-fortified cheese had higher protein and slightly higher fat and ash contents, whereas moisture was similar for both cheeses. Zinc fortification did not affect culture activity during cheese making or during the 2-mo aging period. The TBA value of control cheese was higher than that of zinc-fortified cheese at the end of ripening. Although zinc-fortified cheese was harder as determined by the texture analyzer, the untrained consumer panel did not detect differences in the sensory attributes and overall quality of the cheeses. Fortification of 16 mg/kg zinc sulfate in cheese milk is a suitable approach to fortifying Cheddar cheese without changing the quality of Cheddar cheese.     

Effects of fat level and maltodextrin on the functional properties of frankfurters formulated with 5, 12 and 30% fat

The effects of fat level (5, 12 and 30%) and maltodextrin on emulsion stability, cook loss, colour, texture and sensory characteristics of frankfurters were investigated. Three fat levels (5, 12 and 30%) were formulated containing added maltodextrin. For each fat level a control was prepared without added maltodextrin giving a total of 6 treatments (3×2 factorial design). Reducing the fat from 30 to 5% increased cook loss and decreased emulsion stability. Panellists detected an increase in juiciness and a decrease in overall texture, overall acceptability when the fat level was reduced from 30 to 5%. Instron texture profile analysis showed a decrease in hardness, chewiness and gumminess and an increase in springiness with decreasing fat level. Maltodextrin addition caused a significant decrease in cook loss of the frankfurters but also decreased the emulsion stability. An interactive effect (P<0.05) occurred between fat level and maltodextrin resulting in no significant difference in hardness, gumminess and chewiness values when maltodextrin was present in the reduced-fat (5 and 12%) frankfurters. Saltiness, overall flavour intensity, overall texture and overall acceptability were unaltered (P>0.05) by maltodextrin. The results indicate that maltodextrin can be used as a suitable fat replacer since it offset some of the changes brought about by fat reduction, decreasing cook loss and maintaining a number of textural and sensory characteristics of the frankfurters.     

Effects of somatic cell counts on the physicochemical and rheological properties of yoghurt made from sheep’s milk

In the present work, yoghurts were made from sheep’s milk with two different somatic cell count (SCC), at low (200 000 cells mL^?1) and high (750 000 cells mL^?1) levels. The characteristics of the final product were analysed for pH, acidity, protein, total solids, fat, syneresis, water holding capacity (WHC) and apparent viscosity. Samples were analysed on days 1, 7 and 14 after production of yoghurts. The SCC had no significant effect either on the acidity or pH of the yoghurt at 24 h (P > 0.05) but a significant effect (P < 0.05) was observed at 168 h. No effects of SCC were observed on total solids and fat content of the yoghurt after 24 and 168 h. High SCC (HSCC) yoghurt had higher protein content (P < 0.05). The yoghurt with the highest SCC had the highest level of syneresis. Viscosity of HSCC yoghurt was higher than that of the low SCC yoghurt on days 1, 7 and 14 of storage. The flow properties also showed that the low SCC yoghurt was softer than that from milk with high content in somatic cells.     

Physical,chemical, microbial,and sensory evaluation and fatty acid profiling of value-added drinking yogurt (laban) under various storage conditions

Yogurt is defined as a coagulated milk product obtained from the fermentation of lactose into lactic acid. Drinking yogurt (laban) was prepared from buffalo milk, cow milk, and a 50:50 blend (cow + buffalo milks) by adding 0.5% carboxymethyl cellulose to each of the 3 milk treatments. Samples were then refrigerated for 7, 14, and 21 d before determination of physical, microbial, and sensory parameters. Yogurt prepared from buffalo milk had higher fat and protein contents, and better taste, aroma, and overall consumer acceptability compared with laban prepared from cow milk or mixed milk. During storage, protein and total solids contents remained unchanged, whereas milk fat, color, appearance, taste, smell, texture, and overall acceptability of laban decreased in the different treatment groups. The acidity of laban increased with storage time. Bacteria, including coliforms, were not found in any treatment group during storage. In conclusion, overall acceptability of laban prepared from buffalo milk was higher than that made from cow milk or mixed milk, but increased storage time reduced the quality of laban prepared from cow, buffalo, or mixed milk.     

A comparison of selected quality characteristics of yoghurts prepared from thermosonicated and conventionally heated milks

Thermosonication (TS) of preheated (45 °C) milk (0.1%, 1.5% and 3.5% fat) for 10 min at an ultrasound frequency of 24 kHz allowed the preparation of yoghurts with rheological properties superior to those of control yoghurts produced from conventionally heated milk (90 °C for 10 min). Texture profile analysis and flow curves showed that yoghurts from the TS milks had stronger gel structures which displayed higher water-holding capacities (WHC) and lower syneresis. Based on averaged data from a sensory panel (n = 30), TS yoghurts showed superior texture and colour properties and samples with a fat content of 0.1% scored best in terms of overall acceptability. Retentions of water-soluble (thiamine and riboflavin) and fat-soluble (retinol and tocopherol) vitamins were similar in TS and conventionally prepared yoghurts.