Quality Of Yogurt Research Articles

Soybean peptides promote yoghurt fermentation and quality.

This research paper was to investigate the influence of soybean peptides addition on viable count of lactic acid bacteria, physicochemical parameters, flavor, and sensory evaluation of yoghurt. The number of fermenting strains (Streptococcus thermophilus + Lactobacillus delbrueckii subsp. bulgaricus) cells in yoghurt (stored at 4 °C for 19 days) added with 0.2% (w/v) of soybean peptides (808.34 Da) reached 1.4 times higher bacterial number than in the control group. A total of 34 volatile substances were detected in this study, while there were 22 volatiles occurred in the control group yoghurt, 30 volatiles were detected in yoghurt added with 0.2% soybean peptides. There was no significant difference in sensory evaluation (p > 0.05) between the yoghurt with and without soybean peptides. In our study, the addition of soybean peptides (0.2%) can be effective both in maintaining the viable bacterial count and yoghurt quality.

Effect of the incorporation of graded levels of turmeric (Curcuma longa) on different qualities of stirred yoghurt

There is an increasing trend in yoghurt consumption due to the health benefits from the gut bacteria present in yoghurt. However, there is need to evaluate other inexpensive nutrient sources such as spices (turmeric) which contain a lot of phytochemicals to make yoghurt more nutritious. Fresh turmeric rhizome was sorted, washed, peeled and milled. Ethanol was added to obtain turmeric extract. The turmeric extract was added to the yoghurt before (YTBF) and after fermentation (YTAF) at different ratios of yoghurt: Turmeric (95:5, 90:10, 85:15, 80:20, 75:25 and 100:0). Proximate composition and sensory characteristics of the blends were determined using standard procedures. Results obtained show that the addition of turmeric extract to the yoghurt had significant (p < 0.05) effect on the parameters analyzed. The protein, fat, ash and carbohydrate content of YTBF samples ranged from 2.70 - 3.98, 1.56 - 1.74, 0.20 - 0.38 and 7.69 - 8.25%, respectively while that of sampled YTAF ranged from 2.64 - 3.85, 1.53 - 1.69, 0.24 - 0.54 and 7.87 - 8.26%, respectively. From the sensory scores, sample with the lowest level of turmeric extract (YTBF1) (95:5) was most preferred and compared favorably with the control sample based on colour, taste and overall acceptability. The incorporation of turmeric extract in yoghurt improved the nutrient content of the yoghurt samples. Increased levels above 10% (90:10) led to a more intense colour and spicy taste which did not appeal to the panelists. Key words: Yoghurt, turmeric, fermentation, proximate composition, sensory characteristics.

Influence of the structure of some types of fillers introduced to the yogurt recipe on changes in its rheological indicators

The data set is obtained regarding changes in viscosity, water-holding capacity, active and titrated acidity of yogurts using natural fillers. The possibility of using vegetable fillers with different types of structure (powder, solid and pasty) in the technology of yogurt is analyzed. The studies are relevant in view of improving the quality of yogurts and giving them the status of natural ones due to removing stabilizers, flavors and aromatic additives from their composition. In addition, the introduction fillers into the recipe of yogurts, as a rule, leads to a deterioration of their rheological parameters: a decrease in viscosity, separation of whey and deterioration of the taste properties of the product. This causes an increase in the amount of flavors and stabilizers introduced into their composition, which negatively affects the population of “living microflora” and the biological value of the product. It is found that all the fillers (strawberry powder, candied beets and strawberry jam) had no negative effect on the fermentation process. The influence of dietary fibers that are part of fillers (candied beets, strawberry powder and strawberry jam) on the rheological properties of the product is investigated. Changes in viscosity, water-holding capacity, active and titrated acidity of yogurts with different types of fillers were determined and analyzed immediately after production and during storage. The positive effect of pectin-containing fillers on the hydrophilic properties of yogurts, which increase the water-holding capacity of the product by 2–3 %, is experimentally shown. Based on the data obtained, the feasibility of using the proposed types of fillers, namely strawberry powder and candied beets, in yogurt production without the use of stabilizers, flavors and other food additives is proved. Storage capacity is found, yogurts are developed and shelf life specified in the regulatory documents is determined

Comparing the microbial quality of traditional and industrial yoghurts

The matrix of milk with high water activity (aw) and neutral pH characterized as a suitable culture for an extensive variety of microbial strains. In this regard, both pathogenic bacteria and fungi are recognized as a main microbial agent that significantly contaminated milk-based products especially yoghurt. Microbial contamination is the most common worry of yoghurt safety that they can effect on the host's healthiness status. The presence of fungi (molds and yeasts) especially Geotrichum candidum (milk mold) in industrial yoghurt and on the equipment of factory is the indicator of weak hygienic situation in producing and packing systems. Some studies have shown that the contamination in traditional yoghurts was greater than industrial ones. Aflatoxins are a cluster of metabolites of molds produced via some toxicogenic strains of Aspergillus such as A. flavus, A. nomius and A. parasiticus foodstuffs. Aflatoxin B1 is the most common mycotoxin in the yoghurt. There is a straight connection between the AFM1 existence in the product and the hazard of diseases in consumers. Accordingly, it is essential to inform fabricators and consumers about the contamination of product to decrease their possible healthiness hazards and commercial concerns. This paper provides an overview of the hygienic quality, presence of Aflatoxins, probiotics, and comparison of the microbial quality in both traditional and industrial yoghurts.

Modeling the effect of vibration on the quality of stirred yogurt during transportation.

When transporting yogurt, vibrations and sharp movements can damage its quality. This study developed a model to connect the changes in yogurt quality with the transportation distance as simulated by the total number of vibrations. Linear regression analysis showed that there was a significant negative correlation between the water holding capacity and hardness of the yogurt over the same transport distance (p < 0.05). The yogurt vibration model was established by combining principal component analysis with a Back-Propagation Artificial Neural Network model. The number of training iterations was 2669, with a correlation coefficient of 0.96611, indicating that the model was reliable. The optimal transportation distance was determined to be within the range from 20rpm for 8h to 100rpm for 4h.

Sugar Content and Nutritional Quality of Child Orientated Ready to Eat Cereals and Yoghurts in the UK and Latin America; Does Food Policy Matter?

Ready to eat breakfast cereals (REBCs) and yoghurts provide important nutrients to children’s diets, but concerns about their high sugar content exist. Food reformulation could contribute to sugar reduction, but policies across countries are not uniform. We aimed to compare the sugar content and nutritional quality of child-orientated REBCs and yoghurts in Latin American countries with the UK. In a cross-sectional study, nutritional information, marketing strategies, and claims were collected from the food labels and packaging of products available in Guatemala, Mexico, Ecuador and the UK. Nutritional quality was assessed using the UK Ofcom Nutrient Profiling System. In total, 262 products were analysed (59% REBCs/41% yoghurts). REBCs in the UK had a lower sugar content (mean ± SD) (24.6 ± 6.4) than products in Ecuador (34.6 ± 10.8; p < 0.001), Mexico (32.6 ± 7.6; p = 0.001) and Guatemala (31.5 ± 8.3; p = 0.001). Across countries, there were no differences in the sugar content of yoghurts. A large proportion (83%) of REBCs and 33% of yoghurts were classified as “less healthy”. In conclusion, the sugar content of REBCs in Latin America is higher than those of the UK, which could be attributed to the UK voluntary sugar reduction programme. Sugar reformulation policies are required in Guatemala, Mexico and Ecuador.

Pasteurization Effects on Drinking Yogurt Quality Containing Aloe Vera Gel Extract and Strawberry Pulp

ABSTRACT: Popularity of drinking yogurts is increasing due to significant health benefits, on the go lifestyle and unique valuable ingredients. For the production of drinking yogurt, the present study was being carried out. Effect of various times and temperatures of pasteurization was studied in respect of stability of the product as well as concentration of Aloe Vera gel extract and strawberry pulp was being optimized. A varying heating times and different temperatures of pasteurization (70oC, 80oC, 90oC and 100oC for 5 and 10 minutes) were used in this process. With the storage at refrigeration temperature, evaluation of product for various attributes was carried out including physicochemical (pH, total solids, acidity and viscosity), microbiological (total plate count) and sensory. Effect of storage, time and temperature was seen on yogurt pH that decreased during storage while DY100/10 showed minimum decrease (0.39). Whereas, significant increase was observed in acidity during storage, as DY100/10 showed minimum increase (0.17) while reduction in viscosity was observed and DY100/10 showed minimum reduction (46.33). DY70/5 showed the maximum reduction in viscosity (50) and highest increase in acidity (0.22). During storage, nonsignificant increase in total solids was seen while DY100/10 showed maximum increase (0.3). Increase in storage time led to the decrease in number of total plate count and the sensory attributes (appearance, flavor, sensory acidity, body and texture) were affected significantly. During 20 days of storage, maximum scores were awarded to DY100/10 while minimum scores were obtained by DY70/5. From the present investigation it can be concluded that the best drinking yogurt with respect to shelf life and its sensory acceptance is DY100/10 with a storage period of 20 days.

Utilization of inulin extracted from chicory (Cichorium intybus L.) roots to improve the properties of low-fat synbiotic yoghurt

The present study was aimed to extract and purify inulin from chicory roots and evaluate the physicochemical properties and functional groups of the purified inulin for comparison with those of standard chicory inulin. This study investigated the impact of various inulin concentrations on of low-fat yoghurt quality, including physicochemical, microstructural, textural and sensory properties, the impact of inulin as a prebiotic on the growth and viability of synbiotic yoghurt. The characteristics of the microstructure were investigated by scanning electron microscopy (SEM). For functional group detection, Fourier transform infrared (FTIR) spectroscopy was used. For separate and quantify of inulin content determination were performed on a high-pressure liquid chromatography combined with refractive index detector (HPLC-RID) method. The evaluation of inulin extracted from chicory roots revealed a white powder with a natural taste and no off flavours. Inulin was less sweet than sugar (sucrose) and was moderately soluble in water, colourless, and clear to hazy, with a pH of 5.84. Chicory inulin showed a high content of reducing sugars (4.9%). The addition of inulin at 1% enhanced the microstructural, textural and sensory properties of yoghurt compared to those of the control, and this yoghurt can be considered a functional synbiotic product because it contains both probiotics (>6 log cfu g−1) and prebiotics. The inulin addition to the probiotic yoghurt improved the viability of S. thermophilus, L. bulgaricus, L. acidophilus and B. bifidum during storage. Overall, low-fat synbiotic yoghurt containing 1% inulin was comparable in its performance features to the full-fat probiotic yoghurt control.

The shelf life of yogurt starter and its derivatives based on the microbiological, physical and sensory aspects

Yogurt quality is affected by the yogurt starter. The aim of this study was to determine the shelf life of yogurt starter and its derivatives based on microbiological and physical and sensory aspects. Yogurt starter is made from commercial dry culture, then lowered to 4th derivative, and stored in the refrigerator for up to 25 days. The result showed that there was stability in the viability of total microorganisms and mold in yogurt starter and its derivatives. The viability of lactic acid bacteria (LAB) decreased from F1 to F4. Decreasing pH and little whey formation occurred during the storage. The yogurt quality made from the starter and its derivatives was acceptable. The shelf life of F1, F2, and F3 starter is 25 days, while F4 is 20 days.

The Effect of Skim Milk Concentration on Sensory Quality and pH of Probiotic Yoghurt Added with Red Dragon Fruit (Hylocereus polyrhizus)

Probiotic yog h urt is one of dairy product s that has benefits to the human health . This research aim ed to understand the effect of skim milk concentration on the sensory quality traits and pH of probiotic yoghurt added with red dragon fruit ( Hylocereus polyrhizus ) dices prior to the fermentation. The research method was experimental method with 4 treatments and 3 replications in a completely randomized group design. The data were analyzed using one-way analysis of variance followed by D uncan ’s multiple range test at P<0.05 . The t reatment in this research was different addition levels of skim milk (3% , 5% , 7% , and 9%) to yoghurt . The pH , color, aroma, taste, texture, viscosity and overall acceptance were assessed . The addition of skim milk increased (P<0.05) the acceptability of flavor, texture, viscosity and overall acceptance, in which the addition of skim milk at 9% showed the highest acceptability of taste. However, different addition level of skim milk did not significantly affect pH and the acceptability of color and aroma of yoghurt. The pH of yogurt ranged from 4.06 to 4.26. In addition, the color and aroma of yogurt were in the scale of neither like or dislike , the texture was i n the scale of d islike to l ike, taste, viscosity and overall acceptance we re i n the scale of dis like to neither like nor dislike . In conclusion, skim milk should be used for producing yogurt with red dragon fruit at 9% of whole milk to obtain acceptable product .

Consumer rejection threshold, acceptability rates, physicochemical properties, and shelf-life of strawberry-flavored yogurts with reductions of sugar.

There is an increasing demand for reduced-sugar products due to the worldwide prevalence of obesity, diabetes, and cardiovascular diseases. The aim of this study was to evaluate the effects of sugar (sucrose) reductions on the acceptability, preference, and quality of strawberry-flavored yogurts. A consumer rejection threshold test and an acceptability test (N = 53) were conducted using six yogurt samples with decreasing concentrations of sugar (12-5/100 g). Additional physicochemical tests (pH, °Brix, water-holding-capacity, viscosity, and color) were conducted to examine the quality and shelf-life of strawberry-flavored yogurts with reductions of sucrose during 28 days of storage at 4 °C. Reduction of sucrose affected the acceptability and physicochemical characteristics of yogurts. The consumer rejection threshold showed that sucrose in strawberry-flavored yogurts could be reduced to 5.25/100 g from an initial concentration of 12/100 g without affecting the preferences of consumers. The 71%-sucrose (8.50/100 g of yogurt) was perceived as the most liked (6.27 using a nine-point hedonic scale) and the most preferred (rank sum = 127.50) yogurt sample. For the physicochemical properties of yogurts, the viscosity (3263-5473 cP) decreased, and the color lightness (80.98-85.44) increased during 28 days of storage at 4 °C. Physicochemical properties and preferences were affected by the reduction of sugar. The consumer rejection threshold analysis showed that sucrose can be reduced to less than half of the initial concentration. These findings are useful to understand consumers' acceptability and shelf-life of yogurts with reduced-sugar formulations in the developing of new products. © 2020 Society of Chemical Industry.

WPŁYW CZASU PRZECHOWYWANIA I TEMPERATURY NA JAKOŚĆ JOGURTU NATURALNEGO

WPŁYW CZASU PRZECHOWYWANIA I TEMPERATURY NA JAKOŚĆ JOGURTU NATURALNEGO

The influence of almond flour, inulin and whey protein on the sensory and microbiological quality of goat milk yogurt

A set of six formulations of goat yogurt added with mix of starter (Lactobacillus bulgaricus and Streptococcus thermophilus), inulin, almond flour and whey protein have been evaluated in Italy and Czech Republic by microbiological and sensory analyses. The yogurt were prepared in the two laboratories involved in testing using the same raw materials found on the Italian market and provided to Czech researchers. The panel of each country separately defined sensory profiles by applying the same methodology. The results had shown a different discrimination of samples: the Italian panel, habitual consumer of goat dairy products, discriminated samples for goat yogurt aroma and flavor; the Czech panel, used to consume fermented milk, discriminated samples for acid descriptor. For both the panels, the addition of inulin was assessed as irrelevant, while the addition of whey was assessed as relevant. The addition of prebiotics, almond flour and inulin, did not affect microbial counts.

ЕКСПРЕС - МЕТОД ВИЗНАЧЕННЯ ІНТЕГРАЛЬНОГО ПОКАЗНИКА ЯКОСТІ ЙОГУРТІВ

методу визначення інтегрального показника йогуртів. Експериментально підтверджено, що редокс-потенціал впливає на інтенсивність біохімічнихпроцесів визрівання молочнокислих продуктів, зокрема, йогуртів. Визначення величини редокс-потенціалу йогурту дає можливість здійснювати контроль за якістю цього молочного продукту та прогнозувати термін його зберігання. Все це дозволяє розглядати редокс-потенціал як інтегральний показник якості молочнокислих продуктів, зокрема, йогуртів.

Utilization of safira taro flour (Colocasia esculenta) as addition of natural stabilizers on yoghurt products

Yogurt is a processed food biotechnology made from milk that has been fermented by Lactobacillus and Streptococcus lactic acid bacteria that have antioxidant activity. The manufacturing process has decreased water holding capacity (whey off), this is caused by a decrease in pH in the range of casein isoelectric points that affect the quality of the final product. The purpose of this study is to maintain the final quality of yogurt with the addition of natural taro flour stabilizers. The research method used is to compare the concentrations of natural stabilizers of 2.5%, 1.25%, 0.165%, 0.1% and incubation time of 9 hours, 18 hours, 24 hours, 34 hours. Parameters observed: analysis of the physico-chemical properties of yogurt. The results showed the best yogurt with fat content (0.51%), potassium (2354.64 mg / kg), nutrient content (energy 612.8 kcal; protein 12.7; carbohydrate 9.85 g; calcium 120.29 g; phosphorus 223, 5g; Iron 20.3g; Vitamin A 484mg; vitamin B 0.387mg; vitamin C 1.81 mg)), and organoleptics showed that panelists preferred the yogurt variant (sweet taste). The best yogurt is that there is no decrease in water binding capacity by adding natural stabilizers with an incubation period of 24 hours with a 0.1% stabilizer.

Physicochemical and microbiological quality of yogurts sold in locality bazaar in Balikesir

Bu çalışmada, Balıkesir ilinde geleneksel yöntemlerle üretilen ve semt pazarlarında satışa sunulan yoğurt örneklerinin fizikokimyasal ve mikrobiyolojik kalitesinin Türk Gıda Kodeksi’ne uygunluğu araştırıldı. Semt pazarlarından toplanan 50 yoğurt örneğinin yağsız kurumadde, yağ, protein, titrasyon asitliği ve pH değerleri sırasıyla; %12,07, %3,06, %4,11, %1,31 ve %4,11 olarak tespit edildi. Örneklerde Koliform, E. coli ve küf/maya sayıları ise sırasıyla 140 EMS/g, 112 EMS/g ve 3,47 log kob/g olarak tespit edildi. Örneklerde laktokok sayısı 7,89 log kob/g ve laktobasil sayısı ise 7,64 log kob/g olarak saptandı. Diğer yandan örneklerin hiçbirinde önemli gıda patojenleri olan Salmonella spp., Listeria monocytogenes ve Staphylococcus aureus belirlenmemiştir. Çalışmamızda elde edilen bulgulara göre %14’ü yağsız kurumadde, %10’unu Koliform bakteri, %8’i E. coli ve % 52’si de maya/küf sayıları yönünden Türk Gıda Kodeks’i Fermente Süt Ürünleri Tebliği’ne (2001*; 2009) uygun olmadığı görülmüştür. Sonuç olarak yoğurt örneklerinde patojen mikroorganizma tespit edilmemiş olsa da hijyen indikatörü mikroorganizmaların yüksekliği nedeniyle üretimde hijyen problemlerinin olduğu ve potansiyel halk sağlığı riskleri taşıyabilecekleri belirlenmiştir.

Development of a microencapsulated synbiotic product and its application in yoghurt

The effect of ten commercial prebiotics on the growth ability of four Lactobacillus strains was studied to develop a synbiotic product. The prebiotic score was calculated to assess the capability of prebiotics that stimulated the growth of Lactobacillus compared to potential pathogens. Although both galacto-oligosaccharide (GOS) and lactitol (LAC) could enhance growth, LAC had a highest prebiotic score value for four Lactobacillus strains. Survival of encapsulated synbiotics forming by Lactobacillus casei 30–1 and LAC in simulated gastrointestinal condition was evaluated. 15 g l−1 LAC provided effective protection with 72.62% encapsulation efficiency and a 3.65 logs reduction. The microcapsules were then added into yoghurt and the result showed that there was an increased survival of probiotics due to the protection of cells by microencapsulation and the promoting effect of LAC on the probiotics growth. However, yoghurt with synbiotic microcapsules showed a reduced quality compared to controls over the storage period. This study had shown that microencapsulation and addition of LAC help to enhance the survival of probiotic stains in yoghurts during storage, but had a negative relationship between the improvement of yoghurt quality and the addition of synbiotic microcapsules.

Effect of Different Starches on the Rheological, Sensory and Storage Attributes of Non-fat Set Yogurt.

This study was conducted to investigate the effect of various native starches on the rheological and textural properties of non-fat set yogurt. The yogurt samples were prepared while using five types of starches (potato, sweet potato, corn, chickpea, and Turkish beans). The physical properties of the prepared yogurt were analyzed while using shear viscosity, viscoelasticity, and texture analysis. The tests were performed after 0, 7, and 15 days storage. The effect of these starches on the yogurt viscoelastic properties, texture, syneresis, and sensory evaluation were determined under optimum conditions. The results showed that adding 1% starch could significantly (p < 0.05) reduce syneresis and improve yogurt firmness. Starches exhibited different effect on the overall quality of the yogurt due to their origin and amylose content. Regardless of the number of storage period duration, all of the samples, including the control behaved as pseudoplastic materials (n < 1) with various levels of pseudoplasticity. Yogurts with corn and tuber starches had the highest consistency coefficient (k), which indicated higher viscosity. The yogurt sample with chickpea starch exhibited the highest G´, making the gel more solid like. Therefore, the influence of tuber starches (potato and sweet potato) on G´ was different when compared to corn or legume starches. The behavior of the starches changed with storage time, where some starches performed better only at the beginning of the storage period duration. Wheying-off was significantly reduced, regardless of starch type. The pH of the yogurt remained unchanged through storage. Sensory evaluation showed a preference for starch-containing samples as compared to the control, regardless of the starch type. The variation in yogurt quality as a function of starch type could be attributed to the starch granule structure, gelatinization mechanism, or amylose content.

Impact of Type and Enzymatic/High Pressure Treatment of Milk on the Quality and Bio-Functional Profile of Yoghurt.

The objective of the present study was to investigate the effect of the high pressure (HP) processing and transglutaminase (TGase) treatment of bovine (cow) or ovine (sheep) milk, when applied individually or sequentially, on the quality parameters and anti-hypertensive and immunomodulatory properties of yoghurt. Low-fat (2% w/w) bovine or ovine milk samples were used. Results showed that HP treatment of milk led to acid gels with equivalent quality attributes to thermal treatment, with the more representative attributes being whey separation and firmness, which ranged from 47.5% to 49.8% and 23.8% to 32.2% for bovine and ovine yoghurt, respectively, and 74.3–89.0 g and 219–220 g for bovine and ovine yoghurt, respectively. On the other hand, TGase treatment of milk, solely or more effectively following HP processing, resulted in the improvement of the textural attributes of yoghurt and reduced whey separation, regardless of milk type, exhibiting values of 32.9% and 8.7% for the whey separation of bovine and ovine yoghurt, respectively, and 333 g and 548 g for the firmness of bovine and ovine yoghurt, respectively. The HP processing and TGase treatment of milk led to the preservation or improvement of the anti-hypertensive activity of the samples, especially in the case in which ovine milk was used, with Inhibitory activity of Angiotensin Converting Enzyme (IACE) values of 76.9% and 88.5% for bovine and ovine yoghurt, respectively. The expression of pro-inflammatory genes decreased and that of anti-inflammatory genes increased in the case of samples from HP-processed and/or TGase-treated milk as compared to the corresponding expressions for samples from thermally treated milk. Thus, it can be stated that, apart from the quality improvement, HP processing and TGase treatment of milk may lead to the enhancement of the bio-functional properties of low-fat yoghurt made from either bovine or ovine milk.

Optimizing the quality and antimicrobial ability of yogurt through a combination of starter and dates puree at different levels

Research on the optimization of the quality and antimicrobial ability of yogurt using a combination of starters (Lactobacillus acidophilus and Streptococcus thermophilus) and dates puree with different levels has been carried out to determine the changes in the quality of yogurt in terms of lactic acid levels, protein content, syneresis and also looking for an antimicrobial ability which was measured based on of inhibition zone formed against the tested bacteria (E.coli and S aureus). A completely randomized design (CRD) factorial pattern was applied consisting of 2 factors, those are factor A which is the level of starter, a1 = 2.5 percent, a2 = 5 percent, and factor B which is the level of dates puree namely b0 = 0 percent, b1 = 10 percent, b2 = 20 percent and b3 = 30 percent. The results showed that the level of dates puree had a very significant effect on lactic acid levels but not so with the starter level. The combination of treatments (P <0.01) affects the protein content but there was no interaction between treatments. Furthermore, there is interaction between treatments and it decreases the syneresis value significantly. It can be concluded that the levels of lactic acid, protein and syneresis of yogurt still have the best quality obtained in the treatment of 5 percent starters and the addition of 20 percent of dates puree. On the other hand, it had a weaker antimicrobial ability