Low-fat Yogurt Research Articles

Optimizing Probiotic Low‐Fat Yogurt: The Benefits of Incorporating Defatted Rice Bran for Enhanced Quality and Functionality

ABSTRACTThis study investigated the effects of incorporating defatted rice bran (DRB) at different concentrations (0.5%, 1%, 1.5%, and 2%) on the quality, microbiological, and sensory characteristics of probiotic low‐fat yogurt (LFY) during a 21‐day storage period at 4°C. DRB is rich in dietary fiber, essential amino acids, vitamins, and bioactive compounds, and its addition aimed to enhance the nutritional and functional properties of LFY. LFY samples were evaluated for proximate composition, hardness, viscosity, syneresis, color characteristics, rheology, and sensory evaluation. Also, microbiological analysis includes total bacterial counts (TBC), Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus thermophilus, Bifidobacterium bifidum counts. Results indicated that DRB addition significantly (p < 0.05) increased probiotic counts, especially at 1% and 1.5% concentrations, with these samples maintaining higher bacterial stability over the storage period. DRB‐added LFY also showed improved nutritional profiles, with increased TS, protein, ash, fiber, and antioxidant activity. Additionally, hardness, viscosity, and rheology (G′ and G″) values significantly (p < 0.05) increased with the addition of DRB, while syneresis significantly (p < 0.05) decreased. However, higher DRB concentrations negatively affected the color, with lightness decreasing and the browning index increasing. This also impacted sensory characteristics, resulting in lower scores for color, flavor, and overall acceptability, particularly in LFY with 2% DRB. To conclude, moderate DRB addition (up to 1.5%) optimally balances the enhancement of probiotic and nutritional properties with acceptable sensory quality offering a viable strategy for producing functional low‐fat yogurt.

Grape pomace high-methoxyl pectin: A new prebiotic stabilizer for low-fat synbiotic yogurt gels - Optimization and characterization.

High-methoxyl pectin (HMP, 72.5 % esterification degree and galacturonic acid content of 67.9 %) was extracted from grape pomace using a sequential ultrasound-microwave extraction. The extracted HMP was used to develop low-fat synbiotic set yogurts containing probiotic cells. Higher grape pomace pectin (GPP) concentrations (0.5-2 %) increased the probiotic bacterial population of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-12. Higher cell viability was observed for L. acidophilus LA-5 compared to B. bifidum BB-12. A response surface optimization showed that the presence of 8.08 Log CFU mL-1L. acidophilus LA-5 and 1.88 % HMP experimentally resulted in the best probiotic viability (10.83 ± 0.11 Log CFU mL-1), overall acceptability (8.03 ± 0.06), and pH (4.25 ± 0.05) values. Compared to pectin-free probiotic yogurts, the optimal yogurt gels presented higher probiotic survivability, lower syneresis, and superior storage-dependent sensory attributes during 21 days of storage. However, a 14-day storage period was generally deemed suitable. The GPP-containing yogurt compared to the pectin-free sample exhibited higher colloidal stability with a larger particle size (433.8 nm vs. 272.5 nm) and lower zeta potential (-20.4 mV vs. -10.6 mV). Field emission-scanning electron (FE-SEM) and fluorescent (FLM) microscopy images confirmed a denser microstructure for GPP-enriched yogurts. The chemical interactions in the yogurt were not affected by enriching with GPP as investigated by FTIR, whereas the steady and dynamic rheological properties were significantly improved. GPP-enriched yogurt had a firmer gel structure with a larger linear region and lower G' compared to the control, indicating a semi-solid state. The GPP as a multi-functional prebiotic ingredient would be promising in designing healthier food products.

A comparative study on utilization of different plant-derived nanomucilage as a fat replacer in yogurt: Product optimization, physicochemical attributes, shelf-life evaluation, and consumer perception with market orientation

This study investigated the utilization of various plant-derived sources for the extraction of nanomucilage as a fat substitute in yogurt production. Colocasia esculenta rhizome mucilage (CEM), Cordia dichotoma fruit mucilage (CDM), and Psyllium husk mucilage (PHM) were extracted using different extraction process and spray drier was utilized to acquire nanomucilage with nano-scaled particles (100–300 nm). Seven different types of yogurts were prepared with the addition of varied mucilage concentrations (1–10 % w/v). Results showed that yogurt with 4.5 % PHM exhibited suitable viscosity, higher water holding capacity, and reduced syneresis over the 16 days of storage. Furthermore, selected sample revealed similar physicochemical, textural, and color attributes as compared to control full fat and skimmed milk yogurt. Moreover, this study revealed that consumers highly accepted mucilage formulated yogurt, with a mean score of 97.16 ± 1.58 %. Overall, nanomucilage can potentially utilized as a sustainable biomaterial for the production of low-fat yogurt.

Effect of dairy products fortified with vitamin d3 on restless legs syndrome in women with premenstrual syndrome, abdominal obesity and vitamin d deficiency: a pilot study

BackgroundsRestless legs syndrome (RLS) is an unpleasant condition that affects the quality of life of patients. Its prevalence in increased in women with premenstrual syndrome (PMS). Vitamin D plays a key role in female reproduction through its impact on calcium homeostasis and neurotransmitters. We aimed to evaluate the effect of dairy products fortified with Vitamin D3 on RLS in women with PMS.Materials and methodsWe conducted a 2.5-month, randomized, total-blinded clinical trial to evaluate the effectiveness of low-fat milk and yogurt fortified with vitamin D on RLS in women with PMS. Among 141 middle-aged women with abdominal obesity, 71 and 70 cases received fortified and non-fortified low-fat dairy products, respectively. All subjects completed a Symptoms Screening Tool (PSST) and RLS questionnaires.ResultsThe results showed that in the women with severe PMS (PSST > 28), serum levels of vitamin D increased significantly following vitamin D fortification. The mean restless legs score in the severe PMS subgroup (PSST > 28) was significantly lower after the intervention (p < 0.05. Serum Vitamin D levels significantly differed between intervention and control groups in all individuals (PSST < 19, PSST 19–28, and PSST > 28) (p < 0.05), but no significant differences were found between RLS scores of the intervention and control groups in the three PMS subgroups (p > 0.05).ConclusionFortifying dairy products with vitamin D3 can increase the serum levels of vitamin D and reduce the RLS severity in women with severe PMS, but not in other groups.

Low-fat yogurt consumption maintains biomarkers of immune function relative to nondairy control food in women with elevated BMI: A randomized controlled crossover trial

Yogurt consumption may help reduce chronic inflammation associated with obesity. However, the underlying mechanism(s) by which yogurt consumption modulates the immune system have not been validated in human intervention studies. We hypothesized that 4-week yogurt consumption (12 oz/day) attenuates systemic inflammation by modulating the proportion of circulating T helper (Th) 17 and regulatory T (Treg) cells in adult women with elevated body mass index (BMI). To test the hypothesis, we conducted a randomized crossover dietary intervention study consisted of a 4-week dietary intervention in which participants consumed 12 oz of either low-fat dairy yogurt or a soy pudding control snack per day, with a 4-week washout between treatments. Thirty-nine healthy adult women with a BMI between 25 and 40 kg/m2 were enrolled and 20 completed the study. Changes in the biometrics, circulating T cells, and markers of systemic and colonic inflammation were assessed between the 2 treatment groups, as well as 24-hour diet recalls were conducted at baseline and following each treatment. The primary study outcome, the change in the proportion of circulating Th17 cells, was unaffected by the treatments. Secondary outcome measures, circulating Treg, Th17, and markers of chronic inflammation, were maintained by yogurt treatment, whereas circulating Treg was increased and interleukin-10 was reduced by control snack treatment. However, circulating Treg changes were not associated with changes to other biomarkers of inflammation, implying other immune cells and/or tissues may mediate circulating biomarkers of chronic inflammation. This study was approved by the University of Wisconsin-Madison institutional review board and registered at ClinicalTrials.gov NCT04149418.

Effect of different types of pectin on the physicochemical, rheology, and sensory properties of low-fat yogurt

Abstract Low-fat yogurt has been defined to contain fat content of not more than 2.0 percent as per The Code of Federal Regulations, FDA, U.S. Nevertheless, the reduced fat content affects the physicochemical properties of yogurt by weakened texture, poor body, syneresis, and sensory quality. This is due to fat globules that govern the protein linkages that are responsible for the yogurt’s texture and firmness. The objectives of this study are to evaluate the physicochemical, rheology properties, and to determine the sensory properties and overall acceptability of low-fat yogurt enriched with different types of pectin. Pectin helps improve the gel characteristics, rheology, and microstructure of set yogurt through interactions with the casein network. Two different types of pectins are used which are low-methoxyl pectin (LMP) and high-methoxyl pectin (HMP). For each type, two different concentrations were used which are 0.5% and 1.0% for both types of pectin. Analysis such as pH measurement, titrable acidity, color measurement, water holding capacity measurement, syneresis measurement, viscosity measurement, microbial analysis, and scanning electron microscopy were conducted. The results from the analysis above were subjected to two-way ANOVA and post hoc Tukey’s test. The addition of LMP (0.5% and 1.0%) showed a positive effect on the quality of yogurt with primary attributes compared to the pectin added with HMP and control sample. In conclusion, the low-fat yogurt had a positive effect due to the enrichment of the pectin. Sample 4 which is the low-fat yogurt with 1.0% of LMP showed better properties compared to other samples.

Enhancing Low-Fat Probiotic Yogurt: The Role of Xanthan Gum in Functionality and Microbiological Quality

The objective of this study was to determine the effect of XG addition on low-fat yogurt (LFY) properties. Pasteurized skimmed buffalo milk (SBM) was heated to 95 ± 2 °C for 16 s, cooled to 40 ± 1 °C, and then divided into six treatment lots. The treatments included the following: T1 (control), T2 (0.2% XG), T3 (0.4% XG), T4 (0.6% XG), T5 (0.8% XG), and T6 (1% XG). A proportion of 2% of a mixed starter culture from Streptococcus thermophilus (ST), Lactobacillus bulgaricus (LB), and Bifidobacterium bifidum (BB) in the ratio 1:1:1 was added. Yogurt was manufactured following the standard manufacturing protocol. Chemical composition and texture were determined at fresh time, while water-holding capacity (WHC), viscosity, and syneresis % were determined at 0, 7, 14, and 21 days of storage. Total bacterial counts (TBC), lactobacilli, streptococci, and bifidobacteria counts were determined at 0, 7, 14, and 21 days of storage. Sensory analysis was performed immediately upon the cooling stage (time zero) and then after 14 and 21 days of storage. The experiment was performed in trice. The results obtained showed that the addition of XG in LFY significantly (p &lt; 0.05) decreases the pH, total protein (TP), and ash, and significantly (p &lt; 0.05) increased the total solids (TS). Additionally, the addition of XG led to a significant (p &lt; 0.05) increase in hardness, WHC, and viscosity; however, syneresis significantly (p &lt; 0.05) decreased. The addition of higher amounts of XG led to a significant (p &lt; 0.05) decrease in the TBC and led to a significant (p &lt; 0.05) increase in counts of ST, LB, and BB during the first two weeks of the storage period. Sensory evaluation revealed that increasing the XG concentration up to 0.8% increased the product’s acceptability among panelists; however, further increasing the concentration to 1% had a detrimental impact on its acceptability. To conclude, this study showed that XG can be used as a stabilizer in the manufacturing of LFY as well as a prebiotic for starter culture and improve the quality of LFY.

Does Yogurt Enriched with Platelet-Activating Factor Inhibitors from Olive Oil By-Products Affect Gut Microbiota and Faecal Metabolites in Healthy Overweight Subjects? (A randomized, parallel, three arm trial.).

The effect of the daily consumption of a low-fat yogurt (150 g) enriched with Platelet-Activating Factor receptor (PAF-R) antagonists, or the plain one, on gut microbiota and faecal metabolites was investigated in healthy overweight subjects. A randomized, three-arm, double-blind, placebo-controlled, parallel-group study was performed that lasted 8 weeks. Blood and stools were collected and analyzed before and after the intervention. Our findings revealed that the intake of the enriched yogurt resulted in a significant increase in the levels of Bifidobacterium spp., Clostridium perfringens group and Firmicutes-to-Bacteroidetes (F/B) ratio. On the other hand, a significant increase in the levels of Lactobacillus and C. perfringens group was detected after the intake of the plain yogurt. The increase in the levels of C. perfringens group was inversely associated with the plasma catabolic enzyme of PAF, namely LpPLA2 (lipoprotein-associated phospholipase A2), a cardiovascular risk marker that has been linked with inflammation and atherosclerosis. Moreover, in the enriched with PAF-R antagonists yogurt group, the increased levels of C. perfringens group were also associated with lower PAF action assessed as ex vivo human platelet-rich plasma (PRP) aggregation. Additionally, a higher % increase in molar ratio of Branched Short Chain Fatty Acids (BSCFAs) was detected for both yogurt groups after the 8 week-intervention compared to control. The consumption of the enriched yogurt also resulted in a significant drop in faecal caproic levels and a trend for lower ratio of butyrate to total volatile fatty acids (VFAs) compared to baseline levels. Yogurt consumption seems to favorably affect gut microbiota while its enrichment with PAF-R antagonists from olive oil by-products, may provide further benefits in healthy overweight subjects. ClinicalTrials.gov (NCT02259205).

Bifidobacterium animalis subsp. lactis BB12-Derived Postbiotic Powders Enhance Antioxidant and Physicochemical Properties of Low-Fat Yoghurt

AbstractFortifying conventional foods with postbiotic powders (PP) is an effective approach for the production of functional products. Preserving both functional properties of PP and the physical characteristics of fortified products is essential during this process. This study aimed to investigate the antioxidant activity and consumer testing of low-fat yoghurt fortified with PP and changes in their physical properties, including rheology, water holding capacity, and microstructure over a 21-day storage period. PP, derived from Bifidobacterium animalis subsp. lactis BB12 grown in cheese whey (CW) and skim milk (SM), was added to the product at 1% individually (B12-CW and B12-SM) and in a mixture (BB12-CW-SM). The results indicated that the antioxidant activity of the samples fortified with PP was 4.6 − 6.3%, almost double the values in samples without PP, despite their similar viability of starters (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) (&gt; 8.5 log cfu/g). Adding BB12-CW significantly reduced mouthfeel, flavor, and overall acceptability of the product, while adding BB12-SM and BB12-CW-SM did not alter any consumer acceptability. Similarly, regardless of PP types, their fortification had negligible effects on viscosity, viscoelastic properties, shear-thinning behaviors, water-holding capacity, and microstructure formation, which remained nearly unchanged during storage. Overall, the addition of PP, particularly BB12-SM and BB12-CW-SM, significantly increased antioxidant activity while preserving important physical and consumer acceptance of yoghurt. These findings underscore the potential of postbiotics as functional ingredients, enhancing both the nutritional values and consumer appeal of yoghurt, thereby promoting its health benefits.

Development of functional low-fat yoghurt fortified with psyllium husk mucilage: quality attributes, microstructure, and antioxidant characteristics [pdf

Development of functional low-fat yoghurt fortified with psyllium husk mucilage: quality attributes, microstructure, and antioxidant characteristics [pdf

Effect of the addition of chickpea protein on the physicochemical properties of low-fat yogurt

In this work, the effect of concentration of chickpea protein and time fermentation on the properties of low-fat yogurt was evaluated. The results show that the concentration of chickpea protein affected the water-holding capacity of the yogurt but had no significant effect on acidity values; however, the time of fermentation affected de acidity. In the other hand, both parameters, concentration of protein and time of fermentation, showed significant effects on viscosity of the yogurt, but the factor that had a greater effect on the viscosity was the protein concentration. The results of the sensory properties demonstrated that there was no significant difference in overall acceptability of the different yogurt treatments. These results demonstrated that chickpea protein has a good potency as a source to produce functional dairy foods.

Development of a probiotic low-fat set yogurt containing concentrated sweet pepper extract.

Yogurt contains various health-promoting components such as beneficial bacteria and bioactive peptides. However, plain yogurt is regarded as a poor source of phenolic compounds, vitamin C, and other substances that give a high antioxidant property to the product. Since the objective of this study was to evaluate the impact of the addition of different concentrated sweet pepper extracts (CSPE) to the yogurt milk formulation on some quality parameters of the probiotic set yogurt during 21 days of cold storage. For the production of probiotic yogurt samples, Lactobacillus acidophilus LA-5 was used as probiotic bacteria. The functional set yogurts containing 5% of yellow, orange, or red CSPE were prepared and compared with probiotic control yogurt (without CSPE). With incorporation of CSPE, a functional yogurt with high viable cell counts of probiotics (>108 cfu/g), appropriate acceptability (acceptance scores more than 7, i.e., good acceptability), and textural quality produced. Fortified CSPE yogurt displayed large flakes with irregular surface and more compact texture as compared to the control sample. Based on the results of the study, the yogurt sample having orange CSPE was selected as the best functional product. After 21 days of storage, orange CSPE had the highest hardness (173.33 mg), consistency (1183.33 mg/s), and probiotic counts (8.3 log cfu/g) than other yogurt samples.

THE INFLUENCE OF STARCH PRODUCTS ON THE RHEOLOGI-CAL, PHYSICAL AND CHEMICAL PROPERTIES OF YOGURT

Expanding the assortment of low-fat yogurt with natural structuring sweeteners and regulated quality indicators is an actual direction of scientific research. The purpose of the study is to study the patterns of influence of the products of enzymatic hydrolysis of corn starch with different dextrose equivalents on the rheological, physical and chemical characteristics of yogurt. Тhe functional and technological properties of starch products of different chemical composition were studied – maltodextrin MD-10, glucose syrup IG-42 and glucose-fructose syrup GFS-42. The possibility of completely replacing dry skimmed milk and sugar in the composition of yogurt with a fat content of 1% drinkable with an equivalent content of dry substances of maltodextrin MD-10 and glucose syrup IG-42, which ensure the formation of rheological characteristics inherent high-quality yogurt. Yogurt with sucrose, which inhibits the organization of macromolecular chains of milk proteins, has the lowest thixotropic ability, and yogurt with maltodextrin MD-10 and glucose syrup IG-42 has the highest. The predominance of higher sugars in the composition of MD-10 maltodextrin lengthens, and the increased content of monosaccharides in GFS-42 accelerates the duration of fermentation of milk mixtures in the technological process of production of yogurt with a fat content of 1.0%. Monosaccharides in the composition of GFS-42 significantly affect the activity of water and at the same time reduce the moisture-retaining capacity of the sour-milk yogurt curd. The degree of influence on the rheological characteristics and moisture-binding capacity of yogurt increases with a decrease in the dextrose equivalent of starch products in the following sequence: GFS-42 → IG-42 → MD-10. So, it is the dextrose equivalent of starch products that is an objective criterion of their technological activity as part of yogurt. The results of the study will allow purposeful management of the process of forming low-fat yogurt quality indicators.

Effects of oxidized konjac glucomannan on physicochemical and sensory properties of set-style yoghurt

This study explored effects of adding oxidized konjac glucomannan (OKGM) at various concentrations (0.5, 1.0, 1.5, 2.0%) to low-fat set-style yoghurt on its physicochemical and sensory properties. The findings indicated that effects of OKGM on yoghurt were contingent on the quantity added. Lower concentrations (0.5 and 1.0%) of OKGM enhanced the yoghurt's texture, including hardness, elasticity, gumminess, and chewiness. Results showed an increase in the yoghurt's apparent viscosity, viscoelasticity, and thixotropy. Microstructural analysis showed that low concentrations of OKGM decreased yoghurt particle size and gel pore space. However, at OKGM concentrations of 1.5% or higher, the yoghurt's gel structure was disrupted. Throughout storage, OKGM slowed environmental acidification, as indicated by a steady pH drop and slight increase in acidity. Additionally, OKGM improved the yoghurt's water-holding capacity and reduced its L∗ value. Consumer acceptance was higher for yoghurt with OKGM compared to the control, offering a reference for creating healthy set-style yoghurt.

Evaluation of lupine seeds (Lupinus albus L.) neutral extract as a texture improver in low-fat yogurt production

Aqueous lupine seeds (Lupinus albus L.) extracts were evaluated as a natural fat substitute in low-fat yogurt production. Thus, the chemical composition, particle size, molecular weight, total phenolic (TPC), and total flavonoids (TFC) of the selected extract were estimated. Also, the antimicrobial activity and antioxidant capacity of selected extract were investigated. Yogurt with neutral lupine extract (NeLP) had the highest all sensorial attributes compared to other extracts. Also, the incorporation of NeLP during low-fat yogurt processing increased the solid content, and viscosity, as well as improved the textural profile and sensorial attributes without any negative effect on the yogurt's color. SEM micrographs of NeLP-yogurt microstructure showed a matrix characterized by large fused casein micelles clusters with comparatively lower porosity compared to control yogurt (without NeLP). The chemical composition of NeLP indicated that the major sugar constituents are glucose and galactose with different molar fractions. The molecular weight of NeLP is 460.5 kDa with a particle size of 1519.9 nm. Also, IC50 of NeLP is 0.589 mg/ml, while TPC and TFC are 7.17, and 0.0137 g/100 g sample, respectively. Hence, lupine neutral extract (0.25%) could be used as a fat replacer or texture improver ingredient in such low-fat yogurt which led to improved its characteristics without any negative defect during 7 days at 5 °C.

Comparison of the impact of saturated fat from full-fat yogurt or low-fat yogurt and butter on cardiometabolic factors: a randomized cross-over trial.

Dairy foods are often a major contributor to dietary saturated fatty acids (SFA) intake. However, different SFA-rich foods may not have the same effects on cardiovascular risk factors. We compared full-fat yogurt with low-fat yogurt and butter for their effects on cardiometabolic risk factors in healthy individuals. Randomized, two-period crossover trial conducted from October 2022 to April 2023 among 30 healthy men and women (15 to receive full-fat yogurt first, and 15 to receive low-fat yogurt and butter first). Participants consumed a diet with 1.5-2 servings of full-fat (4%) yogurt or low-fat (< 1.5) yogurt and 10-15g of butter per day for 4 weeks, with 4 weeks wash-out when they consumed 1.5-2 servings of low-fat milk. At baseline, and the end of each 4 weeks, fasting blood samples were drawn and plasma lipids, glycemic and inflammatory markers as well as expression of some genes in the blood buffy coats fraction were determined. All 30 participants completed the two periods of the study. Apolipoprotein B was higher for the low-fat yogurt and butter [changes from baseline, + 10.06 (95%CI 4.64 to 15.47)] compared with the full-fat yogurt [-4.27 (95%CI, -11.78 to 3.23)] and the difference between two treatment periods was statistically significant (p = 0.004). Non-high-density lipoprotein increased for the low-fat yogurt and butter [change, + 5.06 (95%CI (-1.56 to 11.69) compared with the full-fat yogurt [change, - 4.90 (95%CI, -11.61 to 1.81), with no significant difference between two periods (p = 0.056). There were no between-period differences in other plasma lipid, insulin, and inflammatory biomarkers or leukocyte gene expression of ATP-binding cassette transporter 1 and CD36. This study suggests that short-term intake of SFAs from full-fat yogurt compared to intake from butter and low-fat yogurt has fewer adverse effects on plasma lipid profile. GOV: NCT05589350, 10/15/2022.

Effect of Low-Fat Dairy Products Fortified with Encapsulated Vitamin D3 on Anxiety, Depression and Stress in People with Cardiovascular Risk Factors

Background: Vitamin D deficiency is a worldwide condition, which has been linked to a variety of health-related issues. Vitamin D can be beneficial to cardiovascular patients and those suffering from depression and anxiety, based on Survey of Ultraviolet Intake by Nutritional Approach (SUVINA study), ,showing the potential effects of vitamin D-fortified dairy products on anxiety, depression, and stress in subjects with cardiovascular disease (CVD) risk factors. Methods: It was a quadruple-blind randomized controlled trial. Individuals were randomly allocated to one of four groups: fortified low-fat milk (FM), non-fortified low-fat milk (NFM), fortified low-fat yogurt (FY), and non-fortified low-fat yogurt (NFY). FM and FY groups were fortified with 1500 IU nano-encapsulated vitamin D3. Anthropometric parameters as well as depression, anxiety, and stress scores were measured at baseline and after a ten-week trial in Mashhad, Iran. Results: Totally, 289 participants (143 men, 146 women) with a mean age of 41.86±7.81years were enrolled in the study. There was no statistical difference between the scores of depression, anxiety, and stress in participants with and without CVD risk factors (P&gt;0.05). No statistical difference was found in the subgroup analysis based on milk and yogurt consumption. Conclusions: Fortified low-fat milk containing 1,500 IU of vitamin D has no impact on improving depression, anxiety, and stress during ten weeks. However, further studies with higher vitamin D doses for a longer duration are recommended.

Green efficient preparation and on-line monitoring: Hybrid effect of okra pectin and controlled-temperature ultrasound on physicochemical properties of low-fat yogurt

Pectin replaces fat as a stabilizer in making green low-fat yogurt. Controlled-temperature ultrasonic-assisted fermentation (CTUAF) was used, and its acoustic field was monitored in time-frequency domains during the fermentation. Meanwhile, the effect of the addition of okra pectin (OP) on the acoustic field intensity in the yogurt was discussed. Furthermore, the synergistic effect of ultrasound and OP on the physicochemical and structural properties of yogurt was studied, including post processing operations and storage of yogurt. Results showed that adding OP increased the intensity of acoustic field and improved the efficiency of yogurt fermentation. 0.1% OP, ultrasound and hybrid of both shortened the fermentation time of yogurt by 0.75 h, 0.5 h and 1.0 h, respectively. Ultrasound and OP reduced syneresis and optimized hardness, rheological properties and processing quality of yogurt. The cross-linking of OP with casein increased and filled casein cavities, and ultrasound enhanced this interaction. The hybrid of OP and CTUAF also improved the survival rate of probiotics.

Low Fat Yoghurts Produced with Different Protein Levels and Alternative Natural Sweeteners.

The food industry is looking for substitutes for sucrose in food items due to the excessive consumption of products with added sugar and the demand for healthier products. Alternative natural sweeteners can help achieve this goal. Different types of low-fat yoghurts (1% fat), with low-protein and high-protein levels (3% and 4.5-6.5% protein, respectively), were produced using alternative natural sweeteners. The low-protein yoghurts were made with stevia (0.03% w/w) or agave syrup (4.5% w/w). The high-protein yoghurts were made with stevia (0.04% w/w), xylitol (6% w/w) or honey (6% w/w). Sucrose (6% w/w) was used as a control in both trials. pH and titratable acidity, CIEL*a*b* color parameters, syneresis index, rheology and the texture profile of the low-fat yoghurts were evaluated over refrigerated storage. All products underwent sensory evaluation by an untrained panel. The high-protein yoghurts were found to be more acidic (>1% as lactic acid), had a lower syneresis index (between 2.1 and 16.2%) and a better consistency (stronger gel structure) than the low-protein yoghurts. In terms of rheological parameters, stevia-sweetened yoghurts scored higher than the other sweetened yoghurts, showing a better gel structure. The different sweeteners tested did not significantly affect the sensory properties of the yoghurts, although the high-protein yoghurts scored higher for most of the attributes evaluated. Overall, consumers preferred stevia-sweetened yoghurts to yoghurts sweetened with sucrose or agave for the low-protein yoghurts. Of the tested formulations, those containing high protein with the alternative natural sweetener xylitol received higher scores in all attributes. These results reveal the potential of the tested natural sweeteners as sucrose substitutes, while contributing to improving the nutritional value of yoghurts.

Nano casein-pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt.

Protein complexes with a nutritional value, heat stability, and gelling properties with no negative impact on culture viability have promising application prospects in the fermentation industry. The aim of the study was to investigate the possibility of applying physical modification seeking high-protein-fortified yoghurt production using the nano casein-pectin NCP complex as an active colloidal system with enhanced structural and thermal properties and monitor the quality properties of the physicochemical, heat stability, rheological, starter culture viability and sensory evaluation of fortified products comparing with the plain control throughout the cold storage. High-energy ball milling (HEBM) technique was used to produce nanoparticles of casein powder and smaller particles of pectin individually, and particle size and zeta potential was assessed. Deferent Nano casein-pectin (NCP) complex formulations were prepared, their physicochemical properties were assessed including protein quality via Amino Acid Analyzer (AAA), viscosity, thermogravimetric analysis (TGA), and then used in fortification of skimmed milk and low-fat yoghurt to monitor the fortification effects. The particle sizes showed to be ≈166 nm and 602.6 nm for nano-casein and pectin, respectively. Milk fortification with the NCP complex has significantly increased the nutritional value represented in increased protein content (7.19 g/100 g in NCP5); Ca, P, and S content (2,193.11, 481.21, and 313.77 ppm); and amino acid content with first limiting amino acids; histidine (0.89 mg/g), methionine (0.89 mg/g), and low content of hydrophobic amino acids (HAAs) may cause aggregation. NPC fortification enhanced physicochemical properties announced in enhanced viscosity (62. mP.s in NCP5) and heat stability (up to 200°C) compared with control skimmed milk (SM). NCP yoghurt fortification significantly increased protein content to 11 mg/100 g in T5, enhanced viscosity to 48.44 mP.s in T3, decreased syneresis to 16% in T5, and enhanced LAB viability which was translated in preferable sensorial properties. Applying fortification with nanoparticles of the casein-pectin (NCP) complex balanced the amino acid content and improved physicochemical, rheological, nutritional, and sensorial properties and LAB viability, which can be recommended further in functional food applications.