Evaluation of changes during storage of probiotic dahi at 7°C

Low-fat probiotic dahi (an Indian traditional fermented milk product like yogurt) prepared with lactococci starter and two adjunct probiotic cultures of Lactobacillus acidophilus and Lactobacillus casei was stored at 7°C. The survival of bacterial species was affected during storage of dahi, in which viable counts increased up to 2 days and gradually decreased from 2 days, up to 8 days. The quality of refrigerated dahi was assessed by a panel of trained judges. On storage, pH significantly decreased over storage time, indicating that the dahi samples did not develop much acidity under the storage conditions of the study. However, after 8 days of storage, the samples were disliked by the panel, which reported slight bitterness, which may have been due to proteolysis. Proteolysis increased during storage. More α_s1-casein was degraded than β-casein. On the basis of the results of this study we can conclude that dahi stored up to 8 days may be acceptable to consumers.     

Oral administration of dahi containing probiotic Lactobacillus acidophilus and Lactobacillus casei delayed the progression of streptozotocin-induced diabetes in rats

In this study, the effect of dahi containing probiotic Lactobacillus acidophilus NCDC14 and Lactobacillus casei NCDC19 (73 x 10(8) cfu/g) on progression of streptozotocin (STZ)-induced diabetes in rats (15 g/day/rat) for 28 days was investigated. Feeding of probiotic dahi significantly suppressed the incremental peaks and area under the curve and delayed reduction of insulin secretion during oral glucose tolerance test more than skim milk or control dahi. The feeding of milk products reduced the total cholesterol, triglycerides, LDL and VLDL-cholesterol and increased HDL-cholesterol levels (P<0.05). Moreover, probiotic dahi significantly suppressed STZ-induced oxidative damage in pancreatic tissues by inhibiting the lipid peroxidation and formation of nitric oxide, and preserving antioxidant pool such as glutathione content and activities of superoxide dismutase, catalase and glutathione peroxidase. The results suggest that the supplementation of probiotic Lb. acidophilus and Lb. casei with dahi cultures increased the efficacy of dahi to suppress STZ-induced diabetes in rats by inhibiting depletion of insulin as well as preserving diabetic dyslipidemia, and inhibiting lipid peroxidation and nitrite formation. This may empower antioxidant system of beta-cells and may slow down the reduction of insulin and elevation of blood glucose levels.     

Starch–fenugreek (Trigonella foenum-graecum L.) polysaccharide interactions in pure and soup systems

The effect of replacement of varying levels of a fenugreek polysaccharide (FP) product (0.1–0.9%) on 5% wt/wt corn starch cream soups and pure starch systems was investigated. Pasting, textural and viscoelastic characteristics along with granule size and sensory properties were determined. Significant changes were revealed with increasing FP replacement, with the effects being more pronounced on the soup formulations compared to the effects on pure starch/fenugreek systems.     

Qualitative effects of fresh and dried plum ingredients on vacuum-packaged,sliced hams

Boneless ham muscles (Semimembranosus + Adductor) were injected (20% w/w) with a curing brine containing no plum ingredient (control), fresh plum juice concentrate (FP), dried plum juice concentrate (DP), or spray dried plum powder (PP) at 2.5% or 5%. Hams were cooked, vacuum-packaged, stored at <4 °C and evaluated at 2-week intervals over 10 week. Evaluations were performed on sliced product to determine cook loss, vacuum-package purge, Allo–Kramer shear force, 2-thiobarbituric acid-reactive substances (TBARS), proximate analysis, objective color, sensory panel color and sensory attributes. FP, DP and 2.5% PP increased (P < 0.05) cook loss by 2% to 7% depending on treatment and level, but the highest cook loss (17.7%) was observed in hams with 5% PP. Shear force values increased as the level of plum ingredient increased (P < 0.05) from 2.5% to 5%, and the highest shear values were observed in hams containing 5% FP. There were no differences (P > 0.05) in lipid oxidation among treatments as determined by TBARS and sensory evaluation. FP and PP ham color was similar to the control, but DP had a more intense atypical color of cured ham. Minimal changes in physical, chemical and sensory properties were observed during storage of all treatments.     

Yoghurt added with Lactobacillus casei and sweetened with natural sweeteners and/or prebiotics: Implications on quality parameters and probiotic survival

The effect of addition of natural sugar substitutes (stevia, erythritol or xylitol) and prebiotics (oligofructose or polydextrose) on physicochemical characteristics, probiotic survival (Lactobacillus casei) and sensory acceptance of yoghurts during storage (7 °C, 28 days) was evaluated. Yoghurts with sucrose or sucralose were also prepared. Xylitol and sucralose added yoghurts had physicochemical characteristics and sensory acceptance similar to those of the product with sucrose. Xylitol was more efficient in maintenance of textural characteristics and probiotic survival in simulated gastrointestinal conditions (SGIC) than sucralose. Addition of erythritol and stevia changed the textural parameters, reduced acceptance and decreased probiotic survival in SGIC. Addition of oligofructose or polydextrose improved texture and increased probiotic survival but decreased flavour acceptance. All formulations could be considered probiotic products during shelf life (7 °C, 28 days) with counts higher than 10⁷ cfu mL⁻¹ in the product and 10⁴ cfu mL⁻¹ after SGIC.     

Anti‐obesity effect of feeding probiotic dahi containing Lactobacillus casei NCDC 19 in high fat diet‐induced obese mice

Nowadays, studies about the anti‐obesity potential of probiotics are of growing interest. Lactobacilli are one of the well‐studied probiotics owing to their preventing effect on metabolic disorders. This study was undertaken to access the anti‐obesity effect of probiotic dahi containing Lactobacillus casei NCDC 19 on C57BL/6 mice. Feeding of probiotic dahi showed reduce body weight gain and epididymal fat weights. Moreover, blood glucose, plasma lipids and expression level of leptin were reduced and caecal bifidobacteria counts and adiponectin expression levels were significantly increased. It can be concluded that feeding of probiotic dahi containing L. casei NCDC 19 showed potential anti‐obesity effects.     

Effect of calcium and vitamin D2 fortification on quality characteristics of dahi

Two levels (500 and 600 ppm) of calcium (calcium phosphate and calcium citrate) along with vitamin D₂ (600 IU/L) were fortified in milk for dahi preparation. pH, water‐holding capacity and syneresis of fortified dahi were not affected significantly (P > 0.05). However, acetaldehyde content decreased and setting time increased upon fortification. Microbial count significantly (P < 0.05) decreased in calcium phosphate‐fortified dahi, whereas no difference was observed in calcium citrate‐fortified dahi. Firmness and viscosity decreased in calcium phosphate‐fortified dahi, whereas it increased in calcium citrate‐fortified dahi as compared to control. All dahi samples showed good sensory acceptability.     

茯砖茶添加对益生菌豆腐凝胶特性及抗氧化功能的影响

添加不同体积分数的茯砖茶汁到豆浆中,以植物乳杆菌B1-6为生物凝固剂制备新型益生菌茶豆腐,考察益生菌的生长情况。结合质构分析、持水力以及感官评定的结果,确定茯砖茶汁添加量为2.5%为宜。同时通过测定益生菌茶豆腐的亚铁离子还原力和1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2 picrylhydrazyl,DPPH）自由基清除能力来评价其抗氧化能力。结果表明：添加茯砖茶对益生菌的生长、益生菌豆腐的质构、持水力以及感官有显著提高作用,且添加茯砖茶可以显著增强益生菌豆腐的抗氧化能力。     

Type of starter culture influences on structural and sensorial properties of low protein fermented gels

Organoleptic properties of skimmed milk fermented gels are progressively demanding to produce optimal quality yogurts. Chr‐Hansen trademark registered cultures were used to produce low‐protein (3.4%) gels to assess the ability to redesign the sensorial and textural properties with the choice of starter culture. Resulting gels were assessed for sensorial, textural, rheological, and microstructural properties and compared with a commercial control (4.5% protein). Mouth thickness, syneresis, firmness, elasticity, and consistency values were lower for polysaccharides‐producing cultures. Such cultures contributed to the higher creaminess and tended to give higher ropiness. Observed differences among microstructures of the gel were minute. Microstructural and rheological data corresponded and reflected the instrumental and sensory interpretations. Strong correlations were observed between sensory and instrumental data. Nonprobiotics cultures resulted in promising overall gel properties compared with probiotic cultures according to the principal component analysis. Yet probiotic cultures resulted in lower syneresis than nonprobiotic cultures. Thus, the choice of bacterial culture modifies the sensorial and textural properties of fermented gel with strong correlations, as a result of altered gel network formation with the production of polysaccharides. Inferior textural and sensorial quality aspects, particularly at low protein levels, have negative impact on consumer demand of low protein yogurts. Thus, we attempted to gain required gel textural and sensorial properties with a choice of starter culture with a low protein level. Resulting gel properties at lowered protein content with different starter cultures are not fully known. The present study compares the effect of probiotic and nonprobiotic starter cultures on gel properties, as gel texture and sensory properties are of great interest and thus not willing to be compromised. In addition, we examined the overall texture profile of studied cultures and correlate with sensory properties. Therefore, reducing protein level in milk and achieving required gel properties with the choice of appropriate starter culture is of great commercial interest as a cost‐cutting strategy to produce low‐cost optimum quality yogurt.     

抹茶益生菌有机酸奶的研发及贮存期品质分析

以有机生牛乳和有机白砂糖为主要原料,添加抹茶粉和益生元等配料共同进行发酵,研发抹茶益生菌有机酸奶产品,并对其贮存期品质进行分析。通过单因素试验和正交试验分别考察抹茶粉添加量、菊粉添加量、发酵剂接种量和发酵时间对抹茶益生菌有机酸奶感官品质的影响。结果表明,抹茶益生菌有机酸奶的最优发酵工艺为白砂糖添加量8%、发酵温度42 ℃、发酵时间6 h、抹茶粉添加量0.09%、菊粉添加量1.5%、发酵剂接种量0.01%。在此优化条件下,抹茶益生菌有机酸奶感官评分为97分,酸度为78 °T,产品色泽明亮呈淡绿色、口感细滑、风味浓郁。     

Microstructural, textural, and sensory characteristics of probiotic yogurts fortified with sodium calcium caseinate or whey protein concentrate

The influence of milk protein-based ingredients on the textural characteristics, sensory properties, and microstructure of probiotic yogurt during a refrigerated storage period of 28 d was studied. Milk was fortified with 2% (wt/vol) skim milk powder as control, 2% (wt/vol) sodium calcium caseinate (SCaCN), 2% (wt/vol) whey protein concentrate (WPC) or a blend of 1% (wt/vol) SCaCN and 1% (wt/vol) WPC. A commercial yogurt starter culture and Bifidobacterium lactis Bb12 as probiotic bacteria were used for the production. The fortification with SCaCN improved the firmness and adhesiveness. Higher values of viscosity were also obtained in probiotic yogurts with SCaCN during storage. However, WPC enhanced water-holding capacity more than the caseinate. Addition of SCaCN resulted in a coarse, smooth, and more compact protein network; however, WPC gave finer and bunched structures in the scanning electron microscopy micrographs. The use of SCaCN decreased texture scores in probiotic yogurt; probably due to the lower water-holding capacity and higher syneresis values in the caseinate-added yogurt sample. Therefore, the textural characteristics of probiotic yogurts improved depending on the ingredient variety.     

Antioxidant properties of plum concentrates and powder in precooked roast beef to reduce lipid oxidation

Boneless beef roasts (Semimembranosus + Adductor) were injected (20%) with a brine containing (1) no plum ingredient (control), (2) 2.5 or 5% fresh plum juice concentrate (FP), (3) 2.5 or 5% dried plum juice concentrate (DP), or (4) 2.5 or 5% spray dried plum powder (PP). Whole roasts were cooked, vacuum-packaged and stored at <4.0 °C for 10 wk. At 2 wk intervals, evaluations were performed on sliced product to determine vacuum-packaged purge, Allo-Kramer shear force, lipid oxidation (TBARS), color space values, and sensory attributes. All plum ingredients reduced TBARS values and had minimal effects on tenderness, sensory characteristics, color and appearance. Small changes in purge, color values, TBARS and some sensory properties were found during storage. These results indicate that 2.5% FP or DP could be incorporated into precooked beef roasts to reduce lipid oxidation and potentially, warmed-over flavor (WOF).     

RHEOLOGICAL AND SENSORY PROPERTIES OF POPULAR GREEK FOODSTUFFS: A REVIEW

The rheological and sensory properties that constitute the quality benchmark of Greek foodstuffs are identified in a critical fashion and prevailing practices are discussed in relation to home-made and industrial production. Formulation modifications aimed at enhancing the appeal of products in terms of organoleptic characteristics and nutritional impact are also presented. Olive oil occupies an important position in the Greek diet and it is characterised by a unique flavour. Accurate determination of flavour is carried out using the sensory wheel, which unveils the grade of the product. Among foods with soft-solid characteristics, traditional Feta cheese has a prominent place and it is well known for a salty, slightly acidic taste. Ageing within a year results in textural changes from a soft and elastic consistency to a hard and brittle body. Full and low fat Greek yoghurts are consumed widely locally and abroad. The mouthfeel of the product changes from that of a week gel to a viscous fluid at a fat content of 10% and 2%, respectively. Finally, emulsion-type products range from commercial salamis to traditional sausages, which satisfy culinary requirements for a ‘rubbery' or ‘spreadable' texture depending on the favourite pastime dinner. It is hoped that the treatise will unveil the appetising features of Greek foodstuffs, which are increasingly recognised by the international consumer.     

Characterization of probiotic bacteria involved in fermented milk processing enriched with folic acid

Yogurt products fermented with probiotic bacteria are a consumer trend and a challenge for functional food development. So far, limited research has focused on the behavior of the various probiotic strains used in milk fermentation. In the present study, we characterized folic acid production and the sensory and textural characteristics of yogurt products fermented with probiotic bacteria. Yogurt fermented with Lactobacillus plantarum had improved nutrient content and sensory and textural characteristics, but the presence of L. plantarum significantly impaired the growth and survival of Lactobacillus delbrueckii ssp. bulgaricus during refrigerated storage. Overall, L. plantarum was a good candidate for probiotic yogurt fermentation; further studies are needed to understand the major metabolite path of lactic acid bacteria in complex fermentation.     

Technological optimization of manufacture of probiotic whey cheese matrices

In attempts to optimize their manufacture, whey cheese matrices obtained via thermal processing of whey (leading to protein precipitation) and inoculated with probiotic cultures were tested. A central composite, face-centered design was followed, so a total of 16 experiments were run using fractional addition of bovine milk to feedstock whey, homogenization time, and storage time of whey cheese as processing parameters. Probiotic whey cheese matrices were inoculated with Lactobacillus casei LAFTIL26 at 10% (v/v), whereas control whey cheese matrices were added with skim milk previously acidified with lactic acid to the same level. All whey cheeses were stored at 7 °C up to 14 d. Chemical and sensory analyses were carried out for all samples, as well as rheological characterization by oscillatory viscometry and textural profiling. As expected, differences were found between control and probiotic matrices: fractional addition of milk and storage time were the factors accounting for the most important effects. Estimation of the best operating parameters was via response surface analysis: milk addition at a rate of 10% to 15% (v/v), and homogenization for 5 min led to the best probiotic whey cheeses in terms of texture and organoleptic properties, whereas the best time for consumption was found to be by 9 d of storage following manufacture.     

Antioxidant properties of plum concentrates and powder in precooked roast beef to reduce lipid oxidation

Boneless beef roasts (Semimembranosus + Adductor) were injected (20%) with a brine containing (1) no plum ingredient (control), (2) 2.5 or 5% fresh plum juice concentrate (FP), (3) 2.5 or 5% dried plum juice concentrate (DP), or (4) 2.5 or 5% spray dried plum powder (PP). Whole roasts were cooked, vacuum-packaged and stored at <4.0 °C for 10 wk. At 2 wk intervals, evaluations were performed on sliced product to determine vacuum-packaged purge, Allo-Kramer shear force, lipid oxidation (TBARS), color space values, and sensory attributes. All plum ingredients reduced TBARS values and had minimal effects on tenderness, sensory characteristics, color and appearance. Small changes in purge, color values, TBARS and some sensory properties were found during storage. These results indicate that 2.5% FP or DP could be incorporated into precooked beef roasts to reduce lipid oxidation and potentially, warmed-over flavor (WOF).     

希腊式酸羊奶的研制

以新鲜羊奶为主要原料,添加羊乳清粉,研究了希腊式酸羊奶的工艺条件。 通过单因素试验和正交试验,以感官评分及酸度 为评价指标,确定希腊式酸羊奶的最佳发酵工艺条件。 结果表明,希腊式酸羊奶的最佳发酵工艺条件为羊乳清粉添加量1.0%,接种 量6%,发酵温度42 ℃,发酵时间8 h。 在此最佳条件下,感官评分达到87分,酸度为97 °T。 希腊式酸羊奶质地均匀,口感细腻浓郁,酸甜 适中,发酵乳香味明显,羊膻味不明显,其理化及微生物指标均符合相关国家标准。     

Review Article: Technological Aspects of Prebiotics in Probiotic Fermented Milks

Prebiotics are food components that exert beneficial effects on health of the host, associated with modulation of the intestinal flora via stimulating the growth and/or activity of the probiotics. One of the recommended ways to maintain high viable numbers of probiotic bacteria in the intestine as well as in the probiotic fermented milk products until the time of consumption is via the use of prebiotics. These compounds can also affect sensory profile, physicochemical and rheological characteristics, and economic properties of probiotic fermented milk products. In this article, technological aspects of prebiotics (viability of probiotics in the product as well as the physicochemical, rheological, sensory, and economic characteristics of product) in probiotic fermented milks are reviewed.     

Effect of inulin on the textural and sensory properties of mortadella, a Spanish cooked meat product

Inulin is a fructooligosaccharide with demonstrable beneficial effects on health. Its effect on the textural and sensory properties of mortadella, a Spanish cooked meat product, was studied. Conventional (23% fat) and reduced‐fat sausages (10% fat) were prepared. Fat reduction yields an energy value reduction close to 33%. In both cases, inulin was incorporated, in powder and as gel form, in sufficient amounts to constitute the 2.5%, 5% and 7.5% of the final product. To evaluate the effect of inulin, instrumental measures of texture and sensory analysis (hedonic test) were performed. Textural analysis indicated that powdered inulin increases hardness and this fact was more evident in reduced‐fat sausages which showed that this changes even at concentrations of 2.5%. However, when inulin was incorporated as a gel, textural parameter changed only when the high levels were assayed (7.5%) showing softer sausages independent of the fat content. Sensory analysis was highly favourable and the overall acceptability was good in all batches in spite of the changes observed in texture. It can be established that this product can be enriched with inulin to a maximum level of 7.5% and preferably as gel with a good sensory quality.     

Viability of Lactobacillus acidophilus in rice bran‐enriched stirred yoghurt and the physicochemical and sensory characteristics of product during refrigerated storage

This study was aimed at investigating the fortification of probiotic yoghurt with rice bran to increase nutritional properties of the product. The different levels of rice bran (0.3%, 0.6%, 0.9% and 1.2%) were incorporated into milk. The yoghurt samples were produced after pasteurisation, addition of starter culture and 1% Lactobacillus acidophilus suspension (6 × 10⁸ CFU mL^?1) and incubation. During sample storage in refrigerator, the viability of L. acidophilus, viscosity and physicochemical and sensory properties of product were investigated. Rice bran significantly increased the viability of L. acidophilus (P < 0.05). In addition, all probiotic yoghurts incorporating rice bran indicated higher viscosity and acidity and lower pH and syneresis compared to plain yoghurts. Furthermore, increments in rice bran incorporation levels resulted in a reduction in consumers' sample preferences. In general, the addition of rice bran at a suitable level could increase L. acidophilus viability and improve quality attributes of yoghurt.