酸浆果保健酸乳的质地及理化性质研究

以蛋白质含量、脂肪含量、pH值、持水力、流变学特性和质构特性为主要测定指标,通过单因素试验,研究了酸浆果浆添加量 对酸乳理化及感官性质的影响。结果表明,酸浆果浆添加量的变化对酸乳的理化及感官性质有明显影响;酸浆果浆添加量为10%的 酸乳样品在5组样品中感官评分最高（94.7分）,各项理化指标均符合发酵乳国家标准;酸乳样品的黏聚性和胶着性分别与硬度具有 显著相关性（P＜0.05）;所酿造的酸浆果保健酸奶呈现均匀的橙黄色,组织细腻,具有酸浆果特有的香味,酸甜爽口。     

Influence of proteins on the perception of flavored stirred yogurts

Among yogurt dairy components, protein type is known to modify the texture of the products and the volatility of odorous volatile organic compounds. The aim of this study was to investigate the impact of 3 protein ratios (caseinate to total protein) on the sensory properties of 4% fat, strawberry-flavored stirred yogurts. A sensory methodology study was therefore investigated to choose the most efficient method in terms of sensitivity, quantification, and ease with which the panel could distinguish slight differences in olfactory property between the yogurts. Three kinds of product presentation procedures were compared: a monadic presentation, a comparative presentation, and a comparative presentation with a reference. The results showed that the 3 presentation methods emphasized some important texture differences between the yogurts in the same way. However, the comparative procedure with a reference was the only one to reveal clear olfactory property differences between the yogurts. The main effect of protein ratio variation in yogurt concerned the texture properties, which greatly differed between the 3 yogurts and was confirmed by complex viscosity measurements. Olfactory differences between the yogurts were more subtle. Overall, the flavor intensity and the fruity notes were less intense in the yogurts with the high caseinate ratio than in those with the low ratio. This result was in agreement with the physicochemical measurements, which showed a higher retention of a large majority of aroma compounds of the strawberry flavor in the yogurts with a high caseinate ratio.     

Influence of carrot fibre powder addition on rheological,microstructure and sensory characteristics of stirred-type yogurt

The incorporation of 1% (E1) and 2% (E2) of the carrot fibre powder obtained from carrot discards to yogurts was studied. The effect of the fibre addition on the physicochemical parameters, water-holding capacity (WHC), microbial counts, rheological, microstructure and sensory characteristics of yogurts was studied in comparison with control yogurt without fibre addition (C). Titratable acidity, global composition and microbial counts showed a similar trend among yogurts. Fibre particles seemed to change the organisation of protein aggregates of the gel network. An open structure with bigger aggregates was observed in E1 and E2 yogurts, while the microstructure appeared more homogenous and without granules in C. However, carrot fibre increased the WHC of yogurt. All the yogurt samples exhibited shear-thinning behaviour and no differences were found in the rheological parameters, excepting for E2 that presented a decrease in apparent viscosity at 200 s^-1 compared with C and E1 samples. Trained sensory panel (12 members) indicated an increase in brownish colour, strange flavour, grittiness and aftertaste and a decrease in overall appearance, odour, sweetness and creaminess in yogurts enriched in fibre. In order to mask these negative characteristics, E1 formulation was produced in the same way but strawberry flavour and colour were added. A consumer test (101 volunteers), purchase intention and a Check All That Apply (CATA) questionnaires were carried out. Flavoured and coloured E1 yogurt was pleasant for consumers, since 93% of the consumers selected positive degrees of acceptability and 68% of them manifested that they are willing to consume the product. Therefore, the addition of carrot fibre powder in yogurts could be an alternative to incorporate dietary fibres into dairy foods.     

Fat-free plain yogurt manufactured with inulins of various chain lengths and Lactobacillus acidophilus

ABSTRACT:  Inulin is a prebiotic food ingredient that increases the activity of Lactobacillus acidophilus , increases calcium absorption, and is a good source of dietary fiber. The objective was to determine the effect of short, medium, and long chain inulins on the physicochemical, sensory, and microbiological characteristics of fat-free plain yogurt containing L. acidophilus . Inulins of short (P95), medium (GR), and long (HP) chain lengths were incorporated at 1.5% w/w of the yogurt mix. Viscosity, pH, syneresis, sensory properties (flavor, body and texture, and appearance and color), L. acidophilus counts, and color ( L *, a *, and b *) of yogurts were determined at 1, 11, and 22 d after yogurt manufacture. The P95 containing yogurt had a significantly lower pH than the remaining yogurts, higher flavor scores than the yogurt containing HP, and comparable flavor scores with the control. The yogurts containing HP had less syneresis than the control and a better body and texture than the remaining yogurts. Yogurts containing prebiotics of different chain lengths had comparable L. acidophilus counts with each other but higher counts than the control. However, inulins of various chain lengths did not affect viscosity, color, and product appearance. Chain length of prebiotics affected some quality attributes of probiotic yogurts.     

Rheological and sensory performance of a protein-based sweetener (MNEI), sucrose,and aspartame in yogurt

Sweeteners and flavors are generally added to yogurt to make them more palatable. However, the addition of these ingredients may affect the fermentation process of yogurt as well as its physical and sensory characteristics. Consumers prioritize yogurt products that are “natural.” A modified single-chain form of the natural sweet protein monellin extracted from the fruit of Dioscoreophyllum cumminsii, called MNEI, could be a useful alternative to artificial sweeteners. The aim of the present work was to evaluate new rapid sensory methods in combination with rheology to assess the viability of using MNEI to develop sweetened yogurts without the calories of sugar. We studied the gelation and cooling kinetics of 4 yogurt samples (unsweetened or sweetened with MNEI, aspartame, or sucrose) by using a rheometer. Furthermore, the 4 yogurts, with and without addition of a flavoring agent, were characterized from a sensory perspective using a combination of 2 rapid sensory methods, ultra flash profile and flash profile. Rheological results showed that, when added at typical usage levels, aspartame, sucrose, and MNEI did not generally affect the yogurt fermentation process or its rheological properties. Sensory results demonstrated that texture attributes of yogurts with aspartame and sucrose were strongly linked to sweetness and flavor perception, but this was not true for MNEI-sweetened yogurts. In contrast to results obtained from samples sweetened with sucrose and aspartame, MNEI protein did not sweeten the yogurt when added before fermentation. This study highlights the enhancing effect of flavor on sweetness perception, supporting previous reports that noted synergistic effects between sucrose or aspartame and flavors. Hence, future studies should be conducted to determine how sweet proteins behave in yogurt when added after fermentation.     

Physicochemical and Organoleptic Properties of Yogurt with Cornelian Cherry Paste

Stirred-type fruit-flavored yogurt was made by adding cornelian cherry paste and sugar at different ratios. The effects of the paste and sugar addition on the physicochemical and organoleptic properties of yogurt were examined. The titratable acidity, pH, viscosity, whey separation, and organoleptic properties of experimental yogurts were determined at weekly intervals for 21 days. Statistically significant differences were found between the control and fruit-flavored yogurts in terms of viscosity and whey separation. The addition of the fruit paste and sugar to yogurt resulted in an increase in the whey separation, and a decrease in the viscosity. During the storage, the values of the titratable acidity, viscosity and whey separations of experimental yogurts increased, while pH of the yogurts decreased significantly (P < 0.01). Yogurt with 10 kg/100 kg fruit paste and 10 kg/100 kg sugar was more acceptable and high scored with respect to overall acceptability value by panelists; however the result was not significant statistically.     

添加茶油胶对植物油基酸奶品质特性的影响

以脱脂牛乳和茶油为主要原料,经发酵工艺制成茶油基酸奶。以全乳脂酸奶和脱脂酸奶为对照,研究酸奶的理化、质构、流变性及感官品质等特性并进行相关性分析。结果表明,添加茶油胶能明显改善酸奶的凝乳品质。当茶油胶添加量为3.4%时,酸奶的酸度最高（104 °T）,其硬度、黏稠度、表观黏度等指标均优于对照样品;其感官评分最高（93.99分）,表明其良好的品质和感官接受度,以茶油为原料开发植物油基酸奶具有可行性。     

Lactobacillus Gasseri LGZ 1029 in yogurt: rheological behaviour and volatile compound composition

Yogurt preserves and enhances nutritional value of milk. In this study, we have compared several strains to determine the physicochemical, sensory, rheological and aroma characteristics of different yogurts. We used Lactobacillus gasseri LGZ 1029 (LG), commercial probiotic L. rhamnosus (LGG) and traditional fermentation strains Streptococcus thermophilus and L. bulgaricus (SL). Results showed that the flavour and texture characteristics of mixed-strain yogurts were obviously better than in single-strain yogurts. Addition of LG increased pseudoplastic behaviour, as shown by Herschel–Bulkley model analysis of rheological behaviour. The LG + SL group also had both the highest viscosity consistency index and thickening ability. In addition, a total of 57 volatile compounds were detected in yogurts and the fermentation with the addition of LG was mainly affected by ketones. Our study suggested that a yogurt with new attributes can be produced by using LGZ 1029.     

Lutein Is Stable in Strawberry Yogurt and Does Not Affect its Characteristics

ABSTRACT:  The impact of various levels of lutein on the physicochemical, microbiological, and sensory characteristics of yogurt over its shelf life was determined. Nonfat strawberry yogurts were prepared with 0, 0.5, 1.5, and 3.0 mg lutein per 170 g serving (20% overages were included to account for processing losses). The lutein was incorporated prior to homogenization of the yogurt mix. Stability of lutein, viscosity, pH, syneresis, standard plate counts, coliform counts, color (L*, a*, b*), and sensory evaluation (flavor, body and texture, and appearance and color) were measured at weeks 0, 1, 3, and 5 after product manufacture. The interaction effect between levels of lutein and storage time was significant for a* (redness-greenness) values. Lutein levels remained above target throughout the 5-wk storage study. Lutein did not affect viscosity, pH, syneresis, L* (lightness) and b* (yellowness-blueness) values, standard plate counts, coliform counts, flavor, body, texture, appearance, and color scores. These results suggested that lutein was suitable for inclusion in functional yogurts. The skin and eye health benefits provided by lutein can easily be incorporated into yogurt to complement inherent nutritional properties.     

Yogurt Thickness: Effects on Flavor Perception and Liking

Nine flavored stirred‐style yogurts (thick and thin textured, colored and uncolored, flavored as either cotton candy, lemon‐lime, or strawberry) were evaluated by 120 panelists aged 11 to 14 y to analyze the interactive effects of flavor, thickness, and color on thickness intensity, flavor intensity, and degree‐of‐liking. Yogurt flavor did not affect thickness intensity nor liking ratings. Yogurt thickness did not affect flavor intensity, but flavor liking was affected by both flavor and thickness. Strawberry yogurt was liked equally in both texture systems, but cotton candy and lemon‐lime yogurts were liked more in a thick textured yogurt than a thin yogurt. Colored yogurts were thicker and more flavorful than uncolored yogurts.     

Consumer perception,health information,and instrumental parameters of cupuassu (Theobroma grandiflorum) goat milk yogurts

Although the demand for goat milk products has been growing, they have lower consumer acceptability than products derived from cow milk. However, the addition of cupuassu pulp can be used to improve the formulation of these products. For this reason, the aim of this study was to investigate the influence of new goat milk yogurt manufactured with cupuassu pulp on physicochemical properties, consumers’ perceptions, and overall consumer acceptance. In addition, the effect of antioxidant health information on consumer acceptance and purchase intention of cupuassu goat milk yogurts was evaluated. The results demonstrated a positive expectation regarding linking and familiarity to goat milk products and products with cupuassu pulp. The pH, total phenolic content, lightness, redness, yellowness, and apparent viscosity were potentially affected by the addition of cupuassu, with the highest concentration of cupuassu (10%) exhibiting the greatest changes in parameters. Based on principal component analysis, partial least squares regression, and just-about-right and penalty analysis, the addition of cupuassu pulp improved some sensory attributes of goat milk yogurt, such as cupuassu aroma, cupuassu flavor, yellow color, consistency, and viscosity, which positively influenced product acceptance. In addition, antioxidant health information increased the acceptance and purchase intention of cupuassu goat milk yogurts. Taking into account the parameters investigated in this study, the best scoring formulation was goat milk yogurt with 10% cupuassu pulp. Our results suggest that cupuassu pulp can be considered a potential ingredient to improve the sensory and texture properties of goat milk yogurt. Furthermore, the antioxidant health information could be a sensory strategy to increase the acceptance of cupuassu goat milk yogurts.     

Use of isolated autochthonous starter cultures in yogurt production

The aim of this study was to produce yogurt from Iranian autochthonous starters. Strains of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus were isolated from autochthonous yogurts. The strains were used as starter for yogurt production. Chemical, microbial and organoleptic characteristics of products were examined. There were significant increases in acidity and acetaldehyde content, and significant decreases in pH and microbial population of samples during cold storage. There was no significant difference in organoleptic characteristics (taste, smell and texture) during cold storage. We conclude that autochthonous starters in production of yogurt can be satisfactorily used and the starters can introduce to national microbial collection.     

沙棘添加对乳酸菌发酵牛乳风味和消费者接受度的影响

本研究目的是探究添加沙棘(5％,v/v)对发酵乳风味和消费者接受度的影响.选取本实验室前期从新疆老酸奶、西藏开菲尔颗粒等样品中筛选到的8株乳酸菌进行原味发酵乳和沙棘发酵乳的制备.通过电子鼻(Electronic-nose,E-nose)和电子舌(Electronic-tongue,E-tongue)技术,采用模糊数学综...     

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.     

Evaluation of lactose oxidase as enzymatic antifungal control for Penicillium spoilage in yogurt

In this study, we investigated the antifungal activity of lactose oxidase (LO) as a potential biopreservative in dairy products. Our study objectives were to screen antifungal activity of LO against common mold strains, to detect the minimum inhibitory level of LO against the same strains, and to understand how LO affects the pH and lactic acid bacteria (LAB) counts in set yogurt. Five mold strains (Penicillium chrysogenum, Penicillium citrinum, Penicillium commune, Penicillium decumbens, and Penicillium roqueforti) were used throughout study. These strains were previously isolated from dairy manufacturing plants. Throughout the study, yogurts were stored at 21 ± 2°C for 14 d. Antifungal activity of LO was screened using 2 enzyme levels (1.2 and 12 g/L LO) against selected strains on the surface of a miniature laboratory set-yogurt model. For all tested strains, no visible mold growth was detected on the surface of yogurts covered with LO compared with control yogurt without LO. The minimum inhibitory level of LO against each strain was further investigated using 4 enzyme levels (0.12, 0.48, 0.84, and 1.2 g/L LO) on the miniature laboratory set-yogurt model. We detected 0.84 g/L LO as the minimum level inhibiting visible hyphal growth across strains. The minimum inhibitory level of LO varied for each individual strain. To study the effect of LO on the pH of yogurt, miniature laboratory set-yogurt models were covered with different enzyme levels (0.12, 0.48, 0.84, 1.2, and 12 g/L LO). At d 14, a difference was detected comparing pH values of treatments to control with no LO. Commercial low-fat set yogurt was used to study the effect of LO on LAB survival when yogurt surface was covered with 0.84 g/L LO under the same experimental conditions. Control with no LO was included. At d 14, 3 levels of catalase were added (0, 0.01, and 0.1%) to each treatment. To enumerate LAB, homogenized samples were plated on de Man, Rogosa, and Sharpe agar and incubated. Yogurts with 0.84 g/L LO had lower LAB counts compared with control yogurts, and catalase level did not have a significant effect on LAB counts. Our results demonstrated potential antifungal efficacy of LO against common spoilage organisms in dairy products with residual lactose and relatively low pH. Manufacturers should establish efficacy of LO against mold strains of interest and determine the effects of LO on organoleptic properties and LAB survival in set yogurt.     

Evaluation of physical properties during storage of set and stirred yogurts made from ultra-high pressure homogenization-treated milk

The effects of ultra-high pressure homogenization (UHPH) on cow's milk were investigated and its suitability for yogurt manufacturing was compared with the conventional process currently applied in the yogurt industry. Yogurts were prepared from UHPH-treated milks at 200 and 300 MPa at 40 °C, and yogurts prepared from heat-treated milk at 90 °C for 90 s, homogenized at 15 MPa and enriched with 3% of skim milk powder were used as control samples. This study included determination of titrable acidity, water-holding capacity (WHC), and textural and rheological evaluation of gels in both set-type and stirred yogurts. In order to follow the evolution of yogurts during storage at refrigeration temperature (4–6 °C), all analyses were carried out weekly (1, 7, 14, 21 and 28 days). Results showed that yogurts from UHPH-treated milk presented higher WHC and firmness values compared with the conventional yogurts. However, the disruption of the network from UHPH-treated milk into stirred gels resulted in yogurts with higher consistency, less syneresis but coarser structure than the conventional ones.     

Yogurt Manufactured from Whey-Caseinate Blends and Hydrolyzed Lactose

The replacement of NDM by economical whey-caseinate blends at 50 and 100% in the manufacture of yogurt was studied. Lactose in the yogurt mixes was hydrolyzed to 50% and 75% before fermentation to increase sweetness, which reduced added sucrose and simultaneously reduced lactose. Two taste panels detected flavor differences between yogurts from the 100% replacement formula and the control yogurts containing the full amount of NDM but could not detect flavor differences between the control yogurts and the 50% replacement formula. Although the experienced panelists preferred the unhydrolyzed yogurts over the lactose-hydrolyzed yogurts, the consumer taste panelists could not detect any flavor differences and preferred the unhydrolyzed and hydrolyzed yogurts equally. All yogurts had excellent body and texture. Yogurts made with whey-caseinate blends and less sucrose had lower calorie contents than the control yogurts. Whey-caseinate blends lowered the cost of manufacture, but the enzyme preparation used for lactose hydrolysis raised the cost of manufacture slightly.     

云芝发酵红薯浆水代谢产物对酸奶风味的影响

为明确云芝发酵红薯浆水(Coriolus versicolor fermentation of sweet potato pulp water,CV-SPPW))对酸奶风味的影响,为CV-SPPW改善酸奶品质提供理论依据。本研究通过测定红薯浆水(Sweet potato pulp water,SPPPW)发酵前后的理化指标、代谢产物及酸奶的风味物质。结果表明：CV-SPPW中多糖、黄酮、总酚、三萜的含量分别提高5.79、12.25、11.16、3.78倍,游离氨基酸提高了121.87%。此外,CV-SPPW中棉籽糖、赤藓酮糖、丝氨酸、灵芝酸F等代谢产物分别上升14.7、8.49、43.95、8.03倍,这些代谢产物通过糖类热解、美拉德反应等途径形成酸奶的风味物质。添加CV-SPPW的四组酸奶中主要风味物质：苯乙醛、糠醇、δ-十二内酯、4-壬酮、芳樟醇等的相对气味活度值(relative odor activity value, ROAV)值增加,赋予酸奶玫瑰花香味、甜味、奶油味、果香味。因此,CV-SPPW能够明显改善酸奶品质,提升酸奶的风味特性,具有很好的应用前景。