Processing of high-protein yoghurt – A review

Functional yogurt: a comprehensive review of its nutritional composition and health benefits

Functional yogurt, renowned for its enhanced nutritional profile and potential health benefits, has emerged as a promising functional food. This review meticulously examines the nutritional composition of functional yogurt, highlighting its enriched content of probiotics, prebiotics, synbiotics, antioxidants, vitamins, minerals, proteins, and other bioactive compounds, which contribute to its health-promoting properties. Functional yogurt has positively affected digestive health, immune function, metabolic health, and mental well-being. It benefits digestive health by alleviating diarrhoeal symptoms, constipation, colon cancer, irritable bowel syndrome (IBS), Helicobacter pylori infection, and digestive-related allergies. Moreover, the immune-boosting properties of functional yogurt play a pivotal role in reducing the risk of infections and inflammation. In addition, functional yogurt has the potential to improve metabolic health, leading to decreased cholesterol levels and enhanced blood sugar regulation. Emerging research also suggests functional yogurt may positively influence mood, behavior, and cognitive function. Functional yogurt is a valuable addition to the human diet, holding significant implications for public health. In addition to its numerous health benefits, functional yogurt also faces limitations, such as the stability of functional compounds, sensory alterations, potential digestive discomfort, and inconsistent efficacy across populations, highlighting the need for further research and optimization.

INVITED REVIEW: Advances in Yogurt Development: Microbiological Safety, Quality, Functionality, Sensory Evaluation, and Consumer Perceptions across Different Dairy and Plant-based Alternative Sources

Yogurt, as a globally prevalent fermented dairy product, is renowned for its substantial nutritional value and a myriad of health benefits, particularly pertaining to the digestive system. This narrative review elucidates the latest advancements in yogurt development from 2019 to 2024, addressing aspects of microbiological safety, quality, functionality, sensory evaluation, and consumer perceptions across diverse protein sources. The intrinsic quality of yogurt is significantly influenced by its primary ingredient, milk, traditionally derived from animals such as cows, goats, and sheep. In recent years, plant-based yogurts (PBYs) have emerged as a popular alternative to traditional dairy yogurts, that are made from plant sources and offer similar textures and flavors, catering to those seeking non-dairy options. This discussion encompasses the advantages and limitations of various sources and explores methodologies to enhance yogurt quality using these diverse sources. Ensuring the microbiological safety of yogurt is thus paramount to its quality, as it involves both preventing the presence of harmful pathogens and managing spoilage to maintain freshness. This article encapsulates the potential hazards and corresponding antibacterial strategies that safeguard yogurt consumption. These strategies include the use of natural preservatives, advancements in packaging technologies, and the implementation of stringent hygiene practices throughout the production process. Morever, the quality of yogurt is not only dependent on the source but also on the fermentation process and additional ingredients used. By addressing both the prevention of pathogen contamination and the control of spoilage organisms, this article explores not only explores comprehensive approaches but also examines the use of high-quality starter cultures, the role of prebiotics in enhancing probiotic efficacy, and genetic advancements, as well as improvements in the overall nutritional profile and shelf life of yogurt. Techniques to improve texture, flavor, and nutrient content are also discussed, providing a comprehensive overview of current quality enhancement methods.This analysis delves into the intricate mechanisms underpinning probiotic development, including the roles of prebiotics, supplementary starter cultures, and genetic factors that facilitate probiotic proliferation. These benefits include improved digestive health, enhanced immune function, and potential reductions in the risk of certain chronic diseases. Beyond quality and functionality, the sensory evaluation of yogurt remains crucial for consumer acceptance. In recent years, the incorporation of diverse additional ingredients into yogurt has been observed, aimed at augmenting its sensory attributes. This examination reveals these ingredients and their respective functions, such as natural flavorings, sweeteners, and texturizing agents, with the ultimate goal of enhancing overall consumer satisfaction. Consumer preferences exert a profound influence on yogurt production, rendering the understanding of customer opinions essential for devising competitive industry strategies. This article consolidates consumer feedback and preferences, striving to elevate yogurt quality and promote dietary diversity. The analysis includes trends such as the growing demand for organic and non-dairy yogurts, the importance of sustainable practices, and the impact of marketing and packaging on consumer choices. This comprehensive overview serves as a valuable reference for the dairy industry and researchers dedicated to the advancement of yogurt development.

Water-soluble oat extract enriched with mango peel flour: preparation, characterization and application in Greek yogurt

This study aimed to produce water-soluble oat extract enriched with mango peel flour (MPF) as a source of active compounds and to use this ingredient as a partial substitute for whole milk in Greek yogurt (GY) for its nutritional enrichment. Enriched water-soluble oat extracts (EWSOE) were produced with different concentrations of MPF (0%, 1%, 1.5% and 2%) and characterized in relation to pH, titratable acidity, soluble proteins and total phenolics. Three GY formulations were prepared by partially replacing whole milk with EWSOE and the best formulation (in relation to sensory analyzes and phenolics compounds) was selected for storage study, chemical characterization, and sensory acceptance testing. MPF addition increased soluble proteins and total phenolics in EWSOE. GY formulations prepared with EWSOE had similar sensory scores. During storage, GY prepared with EWSOE containing 2% MPF exhibited changes in pH and titratable acidity and a reduction in total phenolics. Color parameters, cholesterol, and fatty acid composition did not change over 21 days of storage. The major fatty acids in GY were oleic and palmitic acids. The selected product had low lactose content (1.2%), achieved satisfactory sensory acceptance in relation to the evaluated attributes, and had lipid (~6.19%) and protein (~3.96%) contents within regulatory requirements. Additionally, EWSOE is a valuable ingredient in GY preparation, offering beneficial nutritional and functional properties.

Advances in the formation mechanism of set-type plant-based yogurt gel: a review

Plant-based yogurt has several advantages over traditional yogurt, such as being lactose and cholesterol-free, making it more suitable for individuals with cardiovascular and gastrointestinal diseases. The formation mechanism of the gel in plant-based yogurt needs more attention because it is associated with the gel properties of yogurt. Most plant proteins, except for soybean protein, have poor functional abilities, such as solubility and gelling properties, which limits their application in most food items. This often results in undesirable mechanical quality of plant-based products, particularly plant-based yogurt gels, including grainy texture, high syneresis, and poor consistency. In this review, we summarize the common formation mechanism of plant-based yogurt gel. The main ingredients, including protein and non-protein components, as well as their interactions involved in the gel are discussed to understand their effects on gel formation and properties. The main interventions and their effects on gel properties are highlighted, which have been shown to improve the properties of plant-based yogurt gels effectively. Each type of intervention method may exhibit desirable advantages in different processes. This review provides new opportunities and theoretical guidance for efficiently improving the gel properties of plant-based yogurt for future consumption.

A comparison of the quality of plain yogurt and its analog made from coconut flesh extract

The aim of this study was to compare the quality of plain yogurt made from cow milk (n = 10) and its plant-based analog made from coconut flesh extract (n = 14). Coconut yogurt alternatives were divided into 2 experimental groups based on differences in their color, which were noted after the packages had been opened. The first group included products with a typical white color (n = 8), and the second group comprised products with a grayish pink color (n = 6) that developed as a result of oxidative processes. In comparison with its plant-based analog, plain yogurt was characterized by higher values of lightness (L*), yellowness (b*) and chroma (C*), higher titratable acidity, a higher content of retinol and α-tocopherol, higher nutritional value of fat, and lower values of water-holding capacity (WHC) and redness (a*). Plain yogurt had lower volatile acidity than its plant-based analog with a grayish pink color. A comparison of yogurt analogs with different colors revealed that the product with a grayish pink color was characterized by a lower value of L*, and higher values of a*, b*, C*, and pH. An analysis of its fatty acid profile demonstrated that it also had a higher proportion of C14:0 and C18:1 cis-9; higher total monounsaturated fatty acids content; a lower proportion of C10:0, C12:0, and C18:2; a lower total content of polyunsaturated fatty acids (PUFA) and essential fatty acids; and a lower ratio of PUFA to saturated fatty acids. The yogurt analog with a grayish pink color had a lower total content of tocopherol isoforms than the remaining products. The yogurt analog with a white color had the highest WHC and γ-tocopherol content. Consumers should be aware of the fact that coconut yogurt alternatives may have nonstandard quality attributes. The differences between such products and yogurt made from cow milk should be explicitly communicated to consumers so that they could make informed purchasing decisions.

Legume milk-based yogurt mimetics structured using glucono-δ-lactone

The potential to produce protein-structured vegan yogurts with legumes was explored to offer an alternative to conventional polysaccharide-based varieties. Glucono-δ-lactone (GDL) was employed as a slow acidifying agent and was investigated for its ability to generate cold-set, yogurt-like gels using soy and lentil milks made using minimal processing steps. Soy (5.3 % protein) and lentil (6.1 % protein) milks were successfully gelled by GDL at concentrations of 0.5 % and 1 % w/w. Soy and lentil milks experienced similar acidification profiles and demonstrated good fits with double-exponential decay models. The physical properties of these legume gels were evaluated and compared to a commercial stirred dairy yogurt. Penetration tests were carried out on intact gels, then repeated after stirring. All intact soy samples demonstrated significantly stronger gel structures compared to the commercial yogurt, and most experienced greater amounts of brittleness. Results showed that the stirring of gels caused a notable decrease in firmness and brittleness in the soy gels, making them more similar to the control. Power-law modelling of viscosity curves demonstrated that all samples experienced non-Newtonian flow behavior (n < 0.29). Susceptibility to syneresis was measured by the degree of liquid loss following centrifugation. The optimization of protein type and GDL concentration to replicate the physical properties of dairy-based yogurts can enhance their consumer acceptance and provide a more customizable and controlled approach alternative to traditional fermentation methods.

Emerging Technologies for Improving Properties, Shelf Life, and Analysis of Dairy Products

Processing results in several kinds of dairy products with variable properties and shelf lives that preserve and often enhance the unique nutritional and biological value of milk [...].

Antioxidant, enzymes inhibitory, physicochemical and sensory properties of instant bio-yoghurts containing multi-purpose natural additives

This study aimed to assess the antioxidant, enzyme inhibitory, physicochemical and sensory properties of instant bio-yoghurts containing multi-purpose natural additives. Multi-purpose natural additives were formulated with three natural additives (sweet detar seed, ginger rhizome, and hibiscus calyx flours, as a thickener, flavourant and colourant, respectively) blends at proportions derived from the Design Expert. The additives' synthetic counterparts were formulated with sodium carboxymethylcellulose, vanilla flavor, and red colourant at the same proportions. After that, yoghurt was produced and the additives blends were incorporated into it either in aqueous extract or flour form, yielding bio-yoghurts designated multi-purpose natural additive extract-containing yoghurt (MNAE-yoghurt), multi-purpose natural additive flour-added yoghurt (MNAF-yoghurt), and their multi-purpose synthetic additives-containing counterparts (MSAE-yoghurt and MSAF-yoghurt). A commercially-available bio-yoghurt served as a control. All the yoghurts were lyophilized to obtain instant bio-yoghurts. Subsequently, bioactive components (total phenolics, tannins, total flavonoids and saponins), antioxidants and enzymes [alpha-amylase, alpha-glucosidase, pancreatic lipase, and angiotensin 1-converting enzyme (ACE)] inhibitory activities, as well as proximate, physicochemical and sensory qualities of the bio-yoghurts were determined. The MNAE-yoghurt and MNAF-yoghurt had higher bioactive constituents, total titratable acid levels, and more potent antioxidant and enzyme inhibitory properties, but a lower pH than their synthetic counterparts and the control. The total phenolics, tannins, total flavonoids and saponins levels of MNAE-yoghurt and MNAF-yoghurt were 14.40 ± 0.24 and 16.54 ± 0.62 mg/g, 1.65 ± 0.04 and 1.74 ± 0.08 mg/g, 4.25 ± 0.03 and 4.40 ± 0.02 mg/g, 0.64 ± 0.01 and 0.66 ± 0.02 mg/g, respectively. Among the natural multi-purpose additives-containing bio-yoghurts, MNAF-yoghurt had higher bioactive constituents and stronger antioxidant and enzymes inhibitory properties. Its α-amylase, α-glucosidase, ACE, and pancreatic lipase IC50 values were 72.47 ± 0.47, 74.07 ± 0.02, 25.58 ± 2.58, and 33.56 ± 29.66 μg/mL, respectively. In contrast, MNAE-yoghurt had the highest protein (13.70 ± 0.85%) and the lowest fat (2.63 ± 0.71%) contents. The sensory attributes of all the bio-yoghurts fell within an acceptable likeness range. Overall, the inclusion of multi-purpose natural additives blends enhanced the instant bio-yoghurts' nutritional, health-promoting, and sensory qualities.

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.

A Thorough Investigation of the Microbiological, Physicochemical, and Sensory Properties of Ewe's Yoghurt Fermented by a Selected Multi-Strain Starter Culture

This work was carried out with the aim to investigate the microbiological, physicochemical, and sensory properties of an innovative yoghurt produced from ewe's milk. Experimental yoghurt productions were performed with a commercial freeze-dried starter preparation and a natural milk starter culture (NMSC) of Streptococcus thermophilus and Lactobacillus delbrueckii. The two yoghurts did not differ for colour parameters, showing an average value of lightness, redness, and yellowness of 94.99, -3.74, and 9.37, respectively. The yoghurt produced using the NMSC as a fermenting agent was characterised by a significantly lower fat percentage and a higher antioxidant potential than commercial starters. Microbiological analysis confirmed the safety of the final product and a level of living lactic acid bacteria of 108 CFU/g. Sensory analysis revealed some differences among yoghurts regarding unpleasant odour, homogeneity, and persistence in the mouth, but the yoghurt processed with NMSC was more appreciated. Thus, the production of ewe's yoghurt fermented by a selected multi-strain starter culture represents an interesting strategy to enlarge the functional ovine dairy product portfolio.

The Effect of Aromatic Plant Extracts Encapsulated in Alginate on the Bioactivity, Textural Characteristics and Shelf Life of Yogurt

The article investigated the antioxidant and antimicrobial activity of extracts from two aromatic plants—Satureja hortensis L. (SE) and Rosmarinus officinalis L. (RE), encapsulated in alginate, on—yogurt properties. The encapsulation efficiency was controlled by FTIR and SEM analysis. In both extracts, the individual polyphenol content was determined by HPLC–DAD–ESI-MS. The total polyphenol content and the antioxidant activity were spectrophotometrically quantified. The antimicrobial properties of SE and RE against gram-positive bacteria (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Geobacillus stearothermophilus), gram-negative bacteria (Escherichia coli, Acinetobacter baumannii, Salmonella abony) and yeasts (Candida albicans) were analyzed in vitro. The encapsulated extracts were used to prepare the functional concentrated yogurt. It was established that the addition of 0.30–0.45% microencapsulated plant extracts caused the inhibition of the post-fermentation process, the improvement of the textural parameters of the yogurt during storage, thus the shelf life of the yogurt increased by seven days, compared to the yogurt simple. Mutual information analysis was applied to establish the correlation between the concentration of the encapsulated extracts on the sensory, physical-chemical, and textural characteristics of the yogurt.

Influence of commercial starter culture on fermentation dynamics and quality characteristics of yogurts obtained with different formulations

BACKGROUND

Four commercial starter cultures containing Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (S1, S2, S3 and S4; S3 also contained Limosilactobacillus fermentum) were compared for fermentation, volatile flavor compounds, physicochemical parameters and microbiology, in yogurt prepared from three milk base formulations with increased protein (B1, B2 and B3).

RESULTS

The fermentation patterns differed among starters, with Yoflex Mild 1.0 (S4) and SLB95 (S2) showing the longest fermentation time, depending on the formulation. At 21 days, S. thermophilus counts were similar among starters and higher than 8.52 log CFU mL^-1 , for all yogurts. The highest counts (6.86 log CFU mL^-1 ) for L. delbrueckii subsp. bulgaricus was found for S2 yogurts made from whey protein hydrolysate (B3). Minor water-holding capacity was detected for YF-L811 (S1) yogurts. Yoflex Harmony 1.0 (S3) starter containing Lim. fermentum produced a distinctive volatile profile characterized by aldehydes with respect to yogurts prepared with S1, S2 and S4, which were characterized by ketones.

CONCLUSION

Results indicate the usefulness of carrying out studies similar to the present one to select the most appropriate process conditions depending on the desired product. © 2022 Society of Chemical Industry.

Application of Lactose-Free Whey Protein to Greek Yogurts: Potential Health Benefits and Impact on Rheological Aspects and Sensory Attributes

The application of β-galactosidase in the fermentation of milk enables the acquirement of lower levels of lactose that are tolerated by lactose maldigesters and can reduce the nutritional consequences of avoiding dairy products. The present study evaluated the viability of the fortification of lactose-free prebiotic Greek yogurt formulas with whey protein concentrate (WPC). Two rotational central composite designs (RCCDs) were applied: one to perform the hydrolysis of the whey protein concentrate and another for the yogurt formulations (α = 2 with 2 central points and 4 axial points). Two β-galactosidase enzymes obtained from Kluyveromyces lactis were used. The content of lactose, glucose, galactose, and lactic acid were determined in the WPC, milk (pasteurized and powdered), and yogurts. The three best formulations regarding the attributes’ viscosity, syneresis, firmness, and elasticity were sensorially evaluated by using a nine-point hedonic scale. A microbiological analysis was performed after 48 h of yogurt production. The characterization of the products and the comparison of the results obtained were evaluated using the Student’s T test and the analysis of variance with Tukey’s test (p-values < 0.05). The application of a lactose-free WPC promoted viscosity, firmness, and elasticity. The syneresis was reduced, and whey increased the protein and calcium content. Lactose-free WPC can be used as a partial substitute for skimmed powdered milk in yogurts. The obtained results are encouraging with respect to the production of lactose-free Greek yogurts by the dairy industry.

Characterization and Evaluation of Proteolysis Products during the Fermentation of Acid Whey and Fish Waste and Potential Applications

Reduction of waste in the food industry is critical to sustainability. This work represents one strategy of valorizing waste streams from the dairy (acid whey) and fisheries industries (fish waste) using fermentation. The main approach was to characterize the peptides produced by this fermentation under three conditions: (1) fermentation without adding inoculum; (2) with the addition of a single lactic acid bacterial strain; and (3) the addition of a consortium of lactic acid bacteria. Previous results indicated that the rapid acidification of this fermentation was advantageous for its food safety and microbial activity. This work complements our previous results by defining the rate of peptide production due to protein digestion and using two-dimensional (2D) gel electrophoresis and proteomic analysis to give a more detailed identification of the peptides produced from different waste streams. These results provide important information on this process for eventual applications in industrial fermentation and, ultimately, the efficient valorization of these waste streams.

Targeted Bottom-Up Mass Spectrometry Approach for the Relative Quantification of Post-Translational Modification of Bovine κ-Casein during Milk Fermentation

κ-casein (κ-CN) is one of the key components in bovine milk, playing a unique role in the structuration of casein micelles. It contains in its chemical structure up to sixteen amino acid residues (mainly serine and threonine) susceptible to modifications, including glycosylation and phosphorylation, which may further be formed during milk processing. In this study, changes in post-translational modification (PTM) of κ-CN during bovine milk fermentation were investigated. One-to-five-day fermented milk samples were produced. A traditional bottom−up proteomics approach was used to establish a multiple-reaction monitoring (MRM) method for relative quantification of κ-CN PTM. Endoproteinase Glu-C was found to efficiently digest the κ-CN molecule. The developed LC-MS method was validated by performing assessments of linearity, precision, repeatability, reproducibility, limit of detection (LOD), and limit of quantification (LOQ). Among the yielded peptides, four of them containing serine and threonine residues were identified and the unmodified as well as the modified variants of each of them were relatively quantified. These peptides were (1) IPTINTIASGEPTSTTE [140, 158], (2) STVATLE [162, 168], (3) DSPE [169, 172], and (4) INTVQVTSTAV [180, 190]. Distribution analysis between unmodified and modified peptides revealed that over 50% of κ-CN was found in one of its modified forms in milk. The fermentation process further significantly altered the composition between unmodified/modified κ-CN, with glycoslaytion being predominant compared to phosphorylation (p < 0.01). Further method development towards α and β-CN fractions and their PTM behavior would be an asset to better understand the changes undergone by milk proteins and the micellar structure during fermentation.

Food proteins in the regulation of blood glucose control

Food proteins, depending on their origin, possess unique characteristics that regulate blood glucose via multiple physiological mechanisms, including the insulinotropic effects of amino acids, the activation of incretins, and slowing gastric emptying rate. The strategies aimed at curbing high blood glucose are important in preventing impaired blood glucose control, including insulin resistance, prediabetes and diabetes. The effect of proteins on blood glucose control can be achieved with high-protein foods short-term, and high-protein diets long-term using foods that are naturally high in protein, such as dairy, meat, soy and pulses, or by formulating high-protein functional food products using protein concentrates and isolates, or blended mixtures of proteins from different sources. Commercial sources of protein powders are represented by proteins and hydrolysates of caseins, whey proteins and their fractions, egg whites, soy, yellow pea and hemp which will be reviewed in this chapter. The effective doses of food protein that are capable of reducing postprandial glycemia start from 7 to 10g and higher per serving; however, the origin of protein, and macronutrient composition of a meal will determine the magnitude and duration of their effect on glycemia. The theoretical and methodological framework to evaluate the effect of foods, including food proteins, on postprandial glycemia for substantiation of health claims on food has been proposed in Canada and is discussed in the context of global efforts to harmonize the international food regulation and labeling.

New insights into perceptions of technology claims in greek-style yogurt: A view in the COVID-19 pandemic

The Covid-19 pandemic has strongly impacted people's lives and the food industry. In this sense, food products claiming nutritional and health-promoting benefits due to the presence of bioactive peptides and probiotics, such as Greek-style yogurt, have been in demand. The objective of this work was to investigate, through word association, the perception of the consumers regarding the seven concepts related to Greek-style yogurt (traditional, ultra-creamy, zero fat, high content proteins, zero lactose, light and with no added sugars), in the context of social isolation due to Covid-19. In this online survey, 346 participants completed a questionnaire. The participants were divided according to health concerns (increased, not changed, or decreased) and eating habits (improved, not changed, or worsened) during the Covid-19 pandemic. Chi-square and prototypical analysis were used as statistical tests. During the Covid-19 pandemic, based on self-report, around 66% of the participants had their eating habits and their concerns about health changed. The general associations were related to the categories pleasure, health, creamy, pleasant texture, food restriction, and loss of sensory quality. 'Health' and 'pleasure' were negatively associated with the conceptualization of Greek-style yogurt. For the zero-fat, light, and sugar-free Greek-style yogurts, the terms creamy and ultra-creamy are sensory appealing to the consumers. In general, the price and concerns about health are factors that strongly influence the purchase intention of Greek-style yogurts. The yogurts were associated with sensory and non-sensory characteristics, which can be useful for marketing strategies for of different product concepts.

E. tapos Yoghurt-A View from Nutritional Composition and Toxicological Evaluation

Elateriospermum tapos (E. tapos) is a natural tropical plant that possess a wide range of health benefits. Recent discovery proves that E. tapos extract is able to reduce weight, increase cognitive performance, and ameliorate anxiety and stress hormone. However, this extraction has not been incorporated into yoghurt, and no toxicity studies have been done previously to prove its safety. Thus, this study was aimed to formulate the ethanolic extracted E. tapos into yoghurt and access the toxicological effects on rodents. Forty female Sprague Dawley (SD) rats were used in this study and force fed with either one of the following doses of 250, 500, 1000, or 2000 mg/kg, while the control group received normal saline. The nutritional analysis result showed that the newly formulated yoghurt comprised 328 kJ of energy per 100 mL of servings, 3.6 g of fats, 8.2 g of carbohydrates, 2.7 g of total protein, and 1.2 g of fibre. The peak intensity of Lactobacillus species was observed at 1.6 × 105 CFU/g with a titratable acidity as lactic acid of 0.432 CFU/g, indicating the ability of the formulated yoghurt in stimulating the growth of Lactobacilli. In the experimental study, the E. tapos yoghurt in a single dose (2000 mg/kg) did not show any treatment related to toxicity in any of the rats observed in an additional 14 days. There were no changes in body weight, food and water intake, plasma biochemistry (ALT, AST, ALP, and creatinine), haematological products, and organ weights of the treated groups compared to the subacute control groups. Histological examination of all organs including liver, heart, and kidney were comparable to the control groups. In toto, oral consumptions of E. tapos yoghurt did not induce any adverse effects on rodents.

Recent application of protein hydrolysates in food texture modification

The demand for clean labels has increased the importance of natural texture modifying ingredients. Proteins are unique compounds that can impart unique textural and structural changes in food. However, lack of solubility and extensive aggregability of proteins have increased the demand for enzymatically hydrolyzed proteins, to impart functional and structural modifications to food products. The review elaborates the recent application of various proteins, protein hydrolysates, and their role in texture modification. The impact of protein hydrolysates interaction with other food macromolecules, the effect of pretreatments, and dependence of various protein functionalities on textural and structural modification of food products with controlled enzymatic hydrolysis are explained in detail. Many researchers have acknowledged the positive effect of enzymatically hydrolyzed proteins on texture modification over natural protein. With enzymatic hydrolysis, various textural properties including foaming, gelling, emulsifying, water holding capacity have been effectively improved. It is evident that each protein is unique and imparts exceptional structural changes to different food products. Thus, selection of protein requires a fundamental understanding of its structure-substrate property relation. For wider applicability in the industrial sector, more studies on interactions at the molecular level, dosage, functionality changes, and sensorial attributes of protein hydrolysates in food systems are required.

Effect of buttermilk and skimmed milk powder on the properties of low-fat yoghurt

Abstract

The aim of the study was to determine the potential of using buttermilk and skimmed milk powders as additives to standardize the dry matter content of milk in the production of low-fat yoghurt. A batch of yoghurt was produced using a starter culture of Lactobacillus delbruecki ssp. bulgaricus and Streptococcus thermophilus. The rates of milk acidification and pH levels were similar for both variants of yoghurt. After chilled storage (21 days), the yoghurt produced from milk supplemented with buttermilk powder was found to contain higher (P ≤ 0.05) levels of lactic acid (1.179%) than that supplemented with skimmed milk (1.154%). The use of buttermilk powder allowed reducing (not significantly, P > 0.05) syneresis in the stored yoghurt. The milk fat in the buttermilk–supplemented yoghurt showed lower (P ≤ 0.05) phospholipids content and exhibited slightly higher phospholipids loss during storage than the yoghurt produced from milk with addition of milk powder. No differences were found between the profile of fatty acids between the yoghurts enriched with skimmed milk powder and those enriched with buttermilk powder. Buttermilk can be used as an additive to produce a novel yoghurt type with modified functional features.

Research Highlights

The use of buttermilk powder did not affect fermentation process, however increased lactic acid content and water-holding capacity of yoghurt.

The yoghurts with added buttermilk contained less phospholipids when compared with yoghurts supplemented with milk powder.

Buttermilk powder can be incorporated as an ingredient in production of novel yoghurt type with improved functional features.

Milk proteins: Processing, gastric coagulation, amino acid availability and muscle protein synthesis

It is well-known that the postprandial muscle protein synthetic response to protein ingestion is regulated on various levels, including dietary protein digestion and amino acid (AA) absorption, splanchnic AA retention, the availability of dietary protein-derived AA in the circulation, delivery of AA to the muscle, uptake of AA by the muscle, and intramuscular signaling. AA availability after consumption of dairy products is primarily determined by the rate of gastric emptying of milk proteins, which is mainly linked to coagulation of milk proteins in the stomach. Caseins form gastric coagula, which make their gastric emptying and subsequent postprandial aminoacidemia notably slower than that of whey proteins. Only recently, the role of processing, food structure, preservation and matrix on coagulation herein has been getting attention. In this review we describe various processes, that affect gastric coagulation of caseins and therewith control gastric emptying, such as the conversion to caseinate, heat treatment in the presence of whey proteins, conversion to stirred yoghurt and enzymatic hydrolysis. Modulating product characteristics by processing can be very useful to steer the gastric behavior of protein, and the subsequent digestion and AA absorption and muscle anabolic response to maintain or increase muscle mass.

Research Status and Prospect for Vibration, Noise and Temperature Rise-Based Effect of Food Transport Pumps on the Characteristics of Liquid Foods

In the field of food processing, the processing of liquid foods has always played an important role. Liquid foods have high requirements for the processing environment and equipment. As the core equipment in liquid foods processing, food transport pumps are widely used in liquid foods production, processing and transportation. Most liquid foods are non-Newtonian and vulnerable to vibration, noise, and temperature rise produced by rotary motions of food transport pumps in operation, which can finally affect foods safety. Therefore, this review summarizes the impact of mechanical vibration, noise, and temperature rise on liquid food products, with the aim of ensuring food safety while designing a cleaner, safer and more reliable food transport pumps in the future.

Quinoa flour as a skim milk powder replacer in concentrated yogurts: Effect on their physicochemical, technological, and sensory properties

Milk standardization with solids (i.e., nonfat milk solids, MSNF) for yogurt manufacture is traditionally achieved by the addition of skim milk powder (SMP). However, the addition of SMP to milk‐based yogurt increases lactose content and decreases both protein content and gel firmness. Thus, in this work, quinoa flour (QF; 0%, 25%, 50%, 75%, and 100% w/w) was used to replace SMP in concentrated yogurt. The physicochemical, textural, and sensory properties and microstructure of the yogurt were evaluated during cold storage. Generally, protein content, water‐holding capacity, and L* value decreased, while syneresis, textural attributes, and viscosity increased with increasing QF content. The substitution of high levels of QF (>25%, w/w) for SMP led to significantly shorter fermentation times, as compared to the control sample. The scanning electron microscopy observations showed significant changes in the yogurt microstructure as a consequence of QF replacement. Samples with 25% (w/w) substitution of QF and control had the highest scores in overall acceptance. According to the results, QF could be applied as an interesting raw material for concentrating the milk‐based yogurt at substitution level of 25% (w/w).

Altering almond protein function through partial enzymatic hydrolysis for creating gel structures in acidic environment

Protein inadequacy is the major problem for most plant-based dairy yoghurt substitutes. This study investigated three limited degree of hydrolysis (DH: 1%, 5%, and 9%) of almond protein and the combined effect of DH and hydrolysed almond protein (HP) to non-hydrolysed almond protein (NP) ratios (HP/NP: 40:60, 20:80, 10:90 and 5:95) on the physicochemical properties of resulting fermentation induced almond-based gel (yoghurt). The gel microstructure, particle size, firmness, pH, water holding capacity (WHC), lubrication, flow, and gelation characteristics were measured and associated with the DH, composition, and SDS-PAGE results. The results show significant differences in gel samples with the same HP/NP (40:60) ratio of protein but different protein DH. A higher DH (9%) resulted in samples with lower hardness (6.03 g), viscosity (0.11 Pa s at 50 s-1), cohesiveness (0.63) and higher friction (0.203 at 10 mm/s) compared to sample with 1% DH with higher hardness - 7.34 g, viscosity at 50 s⁻¹ - 0.16 Pa s, cohesiveness - 0.86 and friction at 10 mm/s - 0.194. Comparing samples with the same DH (5%) but different HP/NP ratios showed smaller coarse microgel particles (21.36 μm) and lower hardness (7.17 g), viscosity (0.14 Pa s at 50 s⁻¹) and friction value (0.189 at 10 mm/s) in samples with high HP/NP (40:60) compared to sample with low HP/NP (5:95) that contained significantly large coarse microgel particles (34.61 μm) with the gel being very hard (9.38 g), highly viscous (0.32 Pa s at 50 s⁻¹), and less lubricating (0.220 at 10 mm/s).

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Enzymatic treatment changes the almond protein profile.

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Increased the degree of hydrolysis weakens the gel strength.

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The more hydrolysed protein used in formulation the softer the gel.

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Limited hydrolysis may contribute to bacterial metabolism.

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The microstructure verifies the improvement of gel's water holding capacity.

Sensory and Biological Potential of Encapsulated Common Bean Protein Hydrolysates Incorporated in a Greek-Style Yogurt Matrix

The work aimed to develop a gel as a protective barrier of common bean protein hydrolysates to be incorporated into a Greek-style yogurt and evaluate the sensory perception and biological potential. The gel was formed by complex coacervation and induced heat at a pH 3.5 and 3:1 biopolymer ratio (whey protein and gum arabic). The gel presented a 39.33% yield, low syneresis (0.37%), and a gel strength of 100 gf. The rheological properties showed an elastic behavior (G′ > G″). The gel with the most stable characteristics favored the incorporation of 2.3 g of hydrolysates to be added into the Greek-style yogurt. Nutritionally, the Greek-style yogurt with the encapsulated hydrolysates presented 9.96% protein, 2.27% fat, and 1.76% carbohydrate. Syneresis (4.64%), titratable acidity (1.39%), and viscoelastic behavior presented similar characteristics to the Greek-style control yogurt. The bitterness and astringency in yogurt with encapsulated hydrolysates decreased 44% and 52%, respectively, compared to the yogurt control with the unencapsulated hydrolysates. The Greek-style yogurt with the encapsulated hydrolysates showed the ability to inhibit enzymes related to carbohydrate metabolism (α-amylase (92.47%) and dipeptidyl peptidase-4 (75.24%) after simulated gastrointestinal digestion). The use of gels could be an alternative to transporting, delivering, and masking off-flavors of common bean protein hydrolysates in food matrices to decrease glucose absorption for type 2 diabetes patients.

High-Protein Concentrated Pro-Yogurt (Pro-WPI) Enriched With Whey Protein Isolate Improved Athletic Anemia and Performance in a Placebo-Controlled Study

Upcoming developments are attracting attention to both high-protein and probiotics supplementation for the sports community to promote good health and exercise performance. This study aimed at the production of high-protein concentrated pro-yogurt (Pro-WPI) enriched with 10 and 20% whey protein isolate (WPI) and investigation of the response of daily consumption on anthropometric, hematology parameters, and athletic performance in parallel with safety consideration assessment. Twenty-four athletes (19.6 ± 1.45 years; 175.96 ± 5.24 cm; 73.16 ± 8.65 kg) were participated in a randomized placebo-control study. They consumed Pro-WPI products with 10 (T1) and 20% (T2) WPI for treatments G1 (Pro-WPI30) and G2 (Pro-WPI60), respectively, 3 times per day/5 days per week/9 weeks. The taste of Pro-WPI products was sour and cheesy, while mouthfeel was described as soft and thick because of the increased protein content in T1 and T2 (14.15 and 22.58%). The hemoglobin of the athletes increased significantly from a baseline of 12.69 g/dl to 16 and 16.66 g/dl in G1 and G2, respectively. Furthermore, the athletic performance was enhanced in vertical jump, long jump, sprinting velocity, half squats, and pushups, which reached 58.75 cm, 255 cm, 3.5 m/s, 218.75 counts, and 85 counts, respectively in G2. The healthy gut microbiome (probiotics) in parallel with increased iron bioavailability by mineral binding (whey bioactive peptides), influenced iron status and can represent a healthy practice to improve athletic anemia and performance. On the other hand, urinary albumin exceeded the border of reference range (<30 mg/g) and reached 38.25 and 44.13 mg/g in G1 and G2, while urine pH was in the normal range (4.5–8). Increased urinary albumin might be due to high rates of protein metabolism that follow high protein intake. This study provided preliminary information on metabolic responses to high protein concentrated yogurt intake in athletes who engaged in daily exercise. Further studies are needed to determine the recommended intensity of 10 and 20% Pro-WPI product consumption to achieve its benefits and avoid implications on kidney function.

Advantages and disadvantages of non-starter lactic acid bacteria from traditional fermented foods: Potential use as starters or probiotics

Traditional fermented foods are a significant source of starter and/or non-starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health-promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.

Profile of Volatile Compounds in Dessert Yogurts Prepared from Cow and Goat Milk, Using Different Starter Cultures and Probiotics

The purpose of this study was to determine the profile of volatile compounds (aroma) and overall flavor in dessert yogurts prepared from cow and goat milk, using three different, commercially available starter cultures, in the presence or absence of probiotic bacteria and to correlate this to organoleptic evaluation results obtained using a consumer acceptability method. The extraction of volatile compounds was carried out by solid phase micro-extraction; separation and analysis by gas chromatography-mass spectrometry. Variations among the different classes of compounds (i.e., aldehydes, alcohols, ketones, volatile acids, hydrocarbons, and terpenes) were recorded for different treatments. The results showed that the main volatiles in the cow milk dessert yogurts without Bifidobacterium BB-12 were: acetaldehyde, 2,3-butanedione, 2,3-pentanedione, 3-OH-2-butanone, 2-propanone, hexanoic acid and limonene). Respective volatiles in cow milk dessert yogurts with Bifidobacterium BB-12 were: acetaldehyde, pentanal, hexanal, the same ketones, acetic acid and limonene). The volatiles in goat milk dessert yogurts without Lactobacillus acidophilus LA-5 were: acetaldehyde, the same ketones, no carboxylic acids, limonene, camphene, α- and β-pinene. Respective volatiles in goat milk dessert yogurts with Lactobacillus acidophilus LA-5 were: aldehydes acetaldehyde, the same ketones, butanoic acid, α-pinene and camphene varying in concentration in different samples. Based on the results of volatiles and organoleptic evaluation, it can be concluded that dessert yogurts from cow milk without probiotic bacterial strains using the mild and classic starter cultures, and dessert yogurts from goat milk with probiotic bacterial strains using the classic and acidic starter cultures are found to be more organoleptically acceptable by consumers. In most cases, a positive correlation was found between dessert yogurt organoleptically determined flavor and volatiles (aldehydes, ketones and carboxylic acids).

Impact of lactic acid bacteria and their metabolites on the techno-functional properties and health benefits of fermented dairy products

After conversion of lactose to lactic acid, several biochemical changes occur such as enhanced protein digestibility, fatty acids release, and production of bioactive compounds etc. during the fermentation process that brings nutritional and quality improvement in the fermented dairy products (FDP). A diverse range of lactic acid bacteria (LAB) is being utilized for the development of FDP with specific desirable techno-functional attributes. This review contributes to the knowledge of basic pathways and changes during fermentation process and the current research on techniques used for identification and quantification of metabolites. The focus of this article is mainly on the metabolites responsible for maintaining the desired attributes and health benefits of FDP as well as their characterization from raw milk. LAB genera including Lactobacillus, Streptococcus, Leuconostoc, Pediococcus and Lactococcus are involved in the fermentation of milk and milk products. LAB species accrue these benefits and desirable properties of FDP producing the bioactive compounds and metabolites using homo-fermentative and heterofermentative pathways. Generation of metabolites vary with incubation and other processing conditions and are analyzed and quantified using highly advanced and sophisticated instrumentation including nuclear magnetic resonance, mass-spectrometry based techniques. Health benefits of FDP are mainly possible due to the biological roles of such metabolites that also cause technological improvements desired by dairy manufacturers and consumers.

Heat-Induced Interaction of Milk Proteins: Impact on Yoghurt Structure

Heating milk for yoghurt preparation has a significant effect on the structural properties of yoghurt. Milk heated at elevated temperature causes denaturation of whey protein, aggregation, and some case gelation. It is important to understand the mechanism involved in each state of stabilization for tailoring the final product. We review the formation of these complexes and their consequence on the physical, rheological, and microstructural properties of acid milk gels. To investigate the interactions between denatured whey protein and casein, the formation of covalent and noncovalent bonds, localization of the complexes, and their impact on ultimate gelation and final yoghurt texture are reviewed. The information regarding this fundamental mechanism will be beneficial to develop uniform quality yoghurt texture and potential interest of future research.

Fat-free fermented concentrated milk products as milk protein-based microgel dispersions: Particle characteristics as key drivers of textural properties

The popularity of fat-free fermented concentrated milk products, such as fresh cheeses and high-protein yogurt, has increased over the recent years, attributed to greater availability and improvements in taste and texture. These improvements have been achieved through modifications and new developments in processing technologies, for example, higher heat treatment intensities and incorporating different membrane filtration technologies. Though numerous processing parameters are discussed in the literature, as well as reasons behind the developments, detailed examinations of how process modifications affect the final textural attributes of these products are lacking. To draw links between processing parameters and texture, we review the literature on fat-free fermented concentrated milk products from the perspective of fermented milk protein-based microgel particles as the basic structural unit. At each main processing step, relationships between process parameters, micro- and macrostructural and sensory (textural) properties are discussed.An overview of particle characteristics that drive structural changes at each processing step is developed in relation to textural characteristics. Using this approach of assessing relationships between structural characteristics of concentrated dispersions of fat-free fermented milk protein-based microgel particles and processing parameters provides a basic context for the selection of optimal parameters to achieve a desired texture.

Physicochemical and microstructural properties of fermentation-induced almond emulsion-filled gels with varying concentrations of protein, fat and sugar contents

The influence of the protein, fat and sugar in almond milk on the formation of the acidic gel was investigated by determining their physicochemical and microstructural properties. The protein, fat and sugar in the almond milk were varied from 2% to 6%, 0.8%-7% and 0.6%-7%, respectively and fermented using Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiles cultures to form a gel structure. Both protein and fat increased the gel strength, viscosity (stirred gel) and lightness of almond yoghurts as the concentration increased. The addition of protein content increased the cohesiveness (from 0.70 to 1.17), water holding capacity (from 28.75% to 52.22%) and D_4,3 value of particle size (from 32.76 μm to 44.41 μm) of almond yoghurt. Fat reduction decreased the firmness (from 6.56 g to 4.69 g), D_4,3 value (from 88.53 μm to 18.37 μm), and water holding capacity (from 48.96% to 27.66%) of almond yoghurt. With sugar addition, almond yoghurt showed increased adhesiveness, decreased lightness and a low pH, with no significant difference in firmness, particle size, and flow behaviour. The confocal images provided evidence that the fortified protein contents homogeneously entrapped fat globules resulting in a more stable gel network and increased fat content led to large fat globule formation resulting in a harder gel network, while the added sugar did not significantly affect the gel network. The results suggested that the protein fortification enhances the texture of almond yoghurt. The fat content of 7% with 3.5% protein showed poor consistency and gel strength of yoghurt. Sugar mainly contributed to bacterial metabolism during fermentation.

Metabolomics of acid whey derived from Greek yogurt

Acid whey, a byproduct of Greek yogurt production, has little commercial value due to its low protein content and is also environmentally harmful when disposed of as waste. However, as a product of microbial fermentation, acid whey could be a rich source of beneficial metabolites associated with fermented foods. This study increases understanding of acid whey composition by providing a complete metabolomic profile of acid whey. Commercial and laboratory-made Greek yogurts, prepared with 3 different bacterial culture combinations, were evaluated. Samples of uncultured milk and cultured whey from each batch were analyzed. Ultra-high-performance liquid chromatography-tandem mass spectrometry metabolomics were used to separate and identify 477 metabolites. Compared with uncultured controls, acid whey from fermented yogurt showed decreases in some metabolites and increases in others, presumably due to the effects of microbial metabolism. Additional metabolites appeared in yogurt whey but not in the uncultured control. Therefore, the effect of microbial fermentation is complex, leading to increases or decreases in potentially bioactive bovine metabolites while generating new microbial compounds that may be beneficial. Metabolite production was significantly affected by combinations of culturing organisms and production location. Differences between laboratory-made and commercial samples could be caused by different starting ingredients, environmental factors, or both.

Effects of microbial transglutaminase levels on donkey cheese production

Microbial transglutaminase (MTGase) is an enzyme widely used in the dairy sector to improve the functional properties of protein-based products via the formation of a network between protein molecules. The aim of this study involving cheese from the milk of donkeys was to evaluate the effects of treatment with MTGase at the concentrations of 0 (control), 5, 8 and 10 U/g milk protein on the cheese-making process parameters, as well as the physical and chemical characteristics of the resulting cheese. MTGase influenced the time of gel formation from rennet addition (P < 0.05), with a delay at the two highest concentrations, accompanied by a lower (P < 0.01) pH of cheese and the lowest (P < 0.01) loss in cheese weight at 24 h of storage. The highest gel viscosity (P < 0.01) was observed at the highest concentration of the enzyme, reaching the value of 70 mPa⋅sec after 60 min. The chemical composition and color of the cheeses were not significantly affected by the inclusion of MTGase, regardless of the enzyme concentration. These findings may be of relevance in adapting the cheese-making process and might help in the design of new dairy products from donkey's milk.