Yogurts enriched with milk proteins: Texture properties, aroma release and sensory perception

Compatibility of pulse protein in the formulation of plant based yogurt: a review of nutri-functional properties and processing impact

With the increased environmental concerns and health awareness among consumers, there has been a notable interest in plant-based dairy alternatives. The plant-based yogurt market has experienced rapid expansion in recent years. Due to challenges related to cultivation, higher cost of production and lower protein content researchers have explored the viability of pulse-based yogurt which has arisen as an economically and nutritionally abundant solution. This review aims to examine the feasibility of utilizing pulse protein for yogurt production. The nutritional, antinutritional, and functional characteristics of various pulses were discussed in detail, alongside the modifications in these properties during the various stages of yogurt manufacturing. The review also sheds light on pivotal findings from existing literature and outlines challenges associated with the production of pulse-based yogurt. Pulses have emerged as promising base materials for yogurt manufacturing due to their favorable nutritional and functional characteristics. Further, the fermentation process can effectively reduce antinutritional components and enhance digestibility. Nonetheless, variations in sensorial and rheological properties were noted when different types of pulses were employed. This issue can be addressed by employing suitable combinations to achieve the desired properties in pulse-based yogurt.

Application of Plant-Based Hydrocolloids on the Textural Profile of Vegan Gummies Supplemented with Turmeric and Black Pepper

Gummies belong to a confectionery category characterized by a hydrocolloid, acting as a stabilizer, forming a network to retain a high-moisture sugar syrup, and hydrocolloids play a key role in shaping the visual appeal, flavour release, and texture of the gel network. This study investigates the potential substitution of gelatin in gummies with plant-based hydrocolloids like agar-agar and guar gum. It is also aimed at optimizing the level of functional ingredients like curcumin and piperine in standardized gummies through incorporation of turmeric and black pepper, respectively. These plant-based gelling agents mimic gelatin's chewable, firm, and elastic texture, catering to broader consumption and suitability for versatile use. Consumer interest in healthier diets has spurred the transition towards plant-based functional foods, leading to the replacement of gelatin gummies with plant-based alternatives. Agar-agar significantly influences gummy texture by contributing to firmness, elasticity, and stable gel formation, imparting essential strength and consistency. Guar gum, recognized as a plant-based hydrocolloid, enhances gummy texture, consistency, and moisture retention through thickening and stabilization. While agar-agar and guar gum individually fell short in achieving the desired textural attributes in the gummies, their combined use (1% agar-agar and 5.5% guar gum) yielded optimal chewiness (1,455.12 ± 1.75 N), gumminess (2251.11 ± 2.14 N), and high overall acceptability (8.96), resembling gelatin-based gummies. The optimized formulation included 40% sugar, 2% citric acid, 2% turmeric, and 0.6% black pepper. The developed vegan gummies contained 56.9 ± 0.09 mg/100 g total phenols, 37.27 ± 1.4% antioxidant capacity, 0.054 ± 0.0012% curcumin, and 0.02 ± 0.008% piperine. Consequently, the combined use of agar-agar and guar gum emerged as stable and effective gelling agents, offering an alternative to gelatin for creating turmeric and black pepper-infused gummies with desirable texture and functional attributes.

Recent advances of silk fibroin materials: From molecular modification and matrix enhancement to possible encapsulation-related functional food applications

Silk fibroin materials are emergingly explored for food applications due to their inherent properties including safe oral consumption, biocompatibility, gelatinization, antioxidant performance, and mechanical properties. However, silk fibroin possesses drawbacks like brittleness owing to its inherent specific composition and structure, which limit their applications in this field. This review discusses current progress about molecular modification methods on silk fibroin such as extraction, blending, self-assembly, enzymatic catalysis, etc., to address these limitations and improve their physical/chemical properties. It also summarizes matrix enhancement strategies including freeze drying, spray drying, electrospinning/electrospraying, microfluidic spinning/wheel spinning, desolvation and supercritical fluid, to generate nano-, submicron-, micron-, or bulk-scale materials. It finally highlights the food applications of silk fibroin materials, including nutraceutical improvement, emulsions, enzyme immobilization and 3D/4D printing. This review also provides insights on potential opportunities (like safe modification, toxicity risk evaluation, and digestion conditions) and possibilities (like digital additive manufacturing) in functional food industry.

Perspectives on the yogurt rheology

The oral processing of yogurt is a dynamic process involving a series of deformation processes. Rheological knowledge is essential to understand the structure and flow properties of yogurt in the mouth and to explore its relationship with sensory perception. Yogurt is rheologically characterized as a non-Newtonian viscoelastic material. The rheological properties of yogurt are affected by many factors, from production to consumption. Therefore, rheological measurements are widely used to predict and control the final quality and structure of yogurts. Recent studies focus on the elucidation of the effects of cultures and processes used in production, as well as the design of different formulations to improve the rheological properties of yogurts. Moreover, the science of tribology, which dominates the surface properties of interacting substances in relative motion to evaluate the structural sensation in the later stages of eating in addition to the rheological properties that give the feeling of structure in the early stages of eating, has also become the focus of recent studies. For a detailed comprehension of the rheological properties of yogurt, this review deals with the factors affecting the rheology of yogurt, analytical methods used to determine rheological properties, microstructural and rheological characterization of yogurt, and tribological evaluations.

Effect of modified okara insoluble dietary fibre on the quality of yoghurt

The aim of this study was to investigate the potential of adding soya bean dregs insoluble dietary fibre (IDF) modified by jet cavitation combined with cellulase to yoghurt to improve its functional properties (Yoghurt was prepared by adding 10 μL of yoghurt fermenter to 100 mL of milk, fermented to pH 4.5 in a constant temperature incubator at 42 °C, and then stored in a refrigerator at 4 °C after adding IDF separately). The results showed that the modified IDF had a rough structure with high water-holding capacity and sodium cholate adsorption capacity. The addition of modified IDF improved the pH, hardness, and elasticity of the yoghurt. During the entire storage period, the titratable acidity and whey precipitation rate of the modified IDF yoghurt gradually increased, and antioxidant activity gradually decreased, and its titratable acidity, whey precipitation rate, and antioxidant activity had a significant advantage compared with those of the blank group yoghurt. In conclusion, the modified soya bean dregs IDF-added yoghurt prepared by jet cavitation combined with the cellulase method has the potential for sodium cholate adsorption capacity and antioxidant activity, which can confer unique functional properties and improve the pH, texture, and reduce whey precipitation of yoghurt. This study provides a scientific basis for the application of soya bean dregs IDF as a fibre fortifier in yoghurt production and suggests innovative ideas for the design of functional dairy products.

Replacement of milk fat by rapeseed oil stabilised emulsion in commercial yogurt

The incorporation of lipid droplets and further characterization of matrices within dairy products may be possible using such adjacent particles as protein complexes/lipids. Among the range of varied emulsions and their functionalities, great attention has recently focused on the fabrication of high internal phase types. Feasibly, stable alternatives structured with health-beneficial lipids like those derived from plants could replace saturated fatty acids. As a fat replacement strategy, the fate of incorporated HIPE would require some adjustments either with storage stability and/or structural feat for the food matrix. Therefore, the replacement of milk fat by rapeseed oil stabilised emulsion in commercial yogurt was investigated. This involved 25%, 50% and 75% rapeseed oil respectively assigned as low (LIPE), medium (MIPE), and high internal phase emulsion (HIPE). Specifically, emulsions were examined by droplet size, encapsulation, pH, zeta potential, phase separation, and rheology. The fat free yogurt supplemented by HIPE were examined by droplet size, zeta potential, pH, color, sensory, texture and microbiological aspects against positive (regular milk fat) and negative (fat free) yogurt controls. Results showed increasing rapeseed oil contents would form smaller droplet-like emulsions. Within the yogurt matrix however, incorporating HIPE would seemingly reduce oil droplet size without much compromise to bacterial viability, sensory, or texture. Overall, this simple method of lipid alternation shows promise in dairy products.

Effects of Pre-Emulsification with Thermal-Denatured Whey Protein on Texture and Microstructure of Reduced-Sodium Processed Cheese

Thermal-denatured whey protein-milk fat emulsion gels with different degrees of pre-emulsification were prepared by pre-emulsifying milk fat with thermal-denatured whey protein and used in the preparation of reduced-sodium processed cheeses. The effect of the thermal-denatured whey protein pre-emulsification process on the texture and microstructure of reduced-sodium processed cheeses was evaluated by studying the composition, color, texture, functional properties, microstructure and sensory analysis of the processed cheeses. The results showed that compared with cheese without pre-emulsified fat (1.5% ES control), the moisture content of cheese with pre-emulsified 100% fat (1.5% ES100) increased by 5.81%, the L* values increased by 7.61%, the hardness increased by 43.24%, and the free oil release decreased by 38%. The microstructure showed that the particle size of fat was significantly reduced, and the distribution was more uniform. In addition, compared with the cheese added with 3% emulsifying salt (3% ES control), the amount of emulsifying salt in the 1.5% ES100 decreased by 50%, but the fat distribution of the two kinds of cheese tended to be consistent, and there was no obvious change in texture characteristics and meltability. Sensory scores increased with the increase in pre-emulsification degree. Overall, the pre-emulsification of milk fat with thermal-denatured whey protein can reduce the sodium content of processed cheese and improve its quality.

Time-Series Sensory Analysis Provided Important TI Parameters for Masking the Beany Flavor of Soymilk

The aim of this study is to provide a new perspective on the development of masking agents by examining the application of their time-series sensory profiles. The analysis of the relationship between 14 time-intensity (TI) parameters and the beany flavor masking ability of 100 flavoring materials indicate that the values of AreaInc, DurDec, and AreaDec, TI parameters related to the flavor release in the increasing and decreasing phases, were significantly higher in the top 10 masking score materials than in the bottom 10 materials. In addition to individual analysis, machine learning analysis, which can derive complex rules from large amounts of data, was performed. Machine learning-based principal component analysis and cluster analysis of the flavoring materials presented AreaInc and AreaDec as TI parameters contributing to the classification of flavor materials and their masking ability. AreaDec was suggested to be particularly important for the beany flavor masking in the two different analyses: an effective masking can be achieved by focusing on the TI profiles of flavor materials. This study proposed that time-series profiles, which are mainly used for the understanding of the sensory characteristics of foods, can be applied to the development of masking agents.

A comprehensive review on yogurt syneresis: effect of processing conditions and added additives

Yogurt, produced by the lactic fermentation of milk base, is an important dairy product worldwide. One of the essential sensory properties of yogurt is the texture, and some textural defects such as weak gel firmness and syneresis likely occur in various types of yogurts, affecting consumer acceptance. In this regard, various strategies such as enrichment of milk-based with different additives and ingredients such as protein-based components (skimmed milk powder (SMP), whey protein-based powders (WP), casein-based powders (CP), and suitable stabilizers, as well as modification of processing conditions (homogenization, fermentation, and cooling), can be applied in order to reduce syneresis. The most effective proteins and stabilizers in syneresis reduction are CP and gelatin, respectively. Furthermore, yogurt's water holding capacity and syneresis can be affected by the type of starter cultures, the protolithic activity, production of extracellular polysaccharides, and inoculation rate. Moreover, optimizing the heat treatment process (85 °C/30 min and 95 °C/5 min), homogenization (single or dual-stage), incubation temperature (around 40 °C), and two-step cooling process can decrease yogurt syneresis. This review is aimed to investigate the effect of fortification of the milk base with various additives and optimization of process conditions on improving texture and preventing syneresis in yogurt.

Protein-Based Fat Replacers: A Focus on Fabrication Methods and Fat-Mimic Mechanisms

The increasing occurrence of obesity and other non-communicable diseases has shifted the human diet towards reduced calorie intake. This drives the market to develop low-fat/non-fat food products with limited deterioration of textural properties. Thus, developing high-quality fat replacers which can replicate the role of fat in the food matrix is essential. Among all the established types of fat replacers, protein-based ones have shown a higher compatibility with a wide range of foods with limited contribution to the total calories, including protein isolate/concentrate, microparticles, and microgels. The approach to fabricating fat replacers varies with their types, such as thermal-mechanical treatment, anti-solvent precipitation, enzymatic hydrolysis, complexation, and emulsification. Their detailed process is summarized in the present review with a focus on the latest findings. The fat-mimic mechanisms of fat replacers have received little attention compared to the fabricating methods; attempts are also made to explain the underlying principles of fat replacers from the physicochemical prospect. Finally, a future direction on the development of desirable fat replacers in a more sustainable way was also pointed out.

Effect of the Heat Exchanger Type on Stirred Yogurt Properties Formulated at Different Total Solids and Fat Contents

In this work stirred yogurts were produced using a technical scale pilot in which the cooling step was processed using either a tubular (THX; low shear) or a plate (PHX, high shear) heat exchanger. The aim was to determine how total solids (TS, adjusted using lactose) and fat contents (FC) impact stirred yogurt properties during storage, depending on the heat exchanger used. Using raw milk, cream, skim milk powder, and lactose, four yogurts were formulated at 16.5% TS and 4.2% proteins, with different FC (0.0, 1.3, 2.6, and 3.9%); one more control yogurt was formulated at 14% TS, 4.2% proteins, and 0.0% FC. Analyses of yogurts (firmness, viscosity, induced syneresis) were realized at days 1, 3, 7, 21, and 34 after production. The addition of lactose between the non-fat yogurt at 14 or 16.5% TS had little to no effect on stirred yogurt properties. Increasing FC reduced syneresis while increasing firmness and viscosity. The use of PHX reduced the syneresis compared to THX; however, it also tended to reduce the firmness of the yogurts with 3.9% FC.

E-nose, E-tongue Combined with GC-IMS to Analyze the Influence of Key Additives during Processing on the Flavor of Infant Formula

In order to analyze the influence of key additives during processing on the flavor of infant formula, the headspace-gas chromatography-ion mobility spectrometry, electronic tongue, and electronic nose techniques were used to evaluate flavor during the processing of stage 1 infant formula milk powder (0-6 months), including the analysis of seven critical additives. A total of 41 volatile compounds were identified, involving 12 aldehydes, 11 ketones, 9 esters, 4 olefins, 2 alcohols, 2 furans, and 1 acid. The electronic nose metal oxide sensor W5S had the highest response, followed by W1S and W2S, illustrating that these three sensors had great effects on distinguishing samples. The response results of the electronic tongue showed that the three sensory attributes of bitter, salty, and umami, as well as the richness of aftertaste, were more prominent, which contributed significantly to evaluating the taste profile and distinguishing among samples. Raw milk is an essential control point in the flavor formation process of stage 1 infant formula milk powder. Demineralized whey powder is the primary source of potential off-flavor components in hydrolyzed milk protein infant formula. This study revealed the quality characteristics and flavor differences of key additives in the production process of stage 1 infant formula milk powder, which could provide theoretical guidance for the quality control and sensory improvement of the industrialized production of infant formula.

Fortification of milk-based yogurt with protein hydrolysates from brewers' spent grain: Evaluation on microstructural properties, lactic acid bacteria profile, lactic acid forming capability and its physical behavior

Current study aimed to evaluate the utilization of protein from brewers' spent grain (BSGP) on microstructural formation as well as rheological behavior, acidity and lactic acid bacteria (LAB) profile during the refrigerated storage. Three different BSGPs were provided including BSGP-C (extracted without enzymatic hydrolysis), BSGP-P (with protease), and BSGP-PF (with protease co-incubated with flavourzyme). The results demonstrated that BSGPs improved lactic acid forming capability in yogurt production to a higher level than milk-protein based enrichment. BSGPs improved the growth and survival of lactic acid bacteria (LAB), particularly BSGP-P in improving the survival rate of L. bulgaricus. Confocal laser scanning microscopy showed that BSGP-P generated a denser, softer and more homogenous surface appearance as well as showed the tendency to form more compact networks; had a weaker initial gel forming, increased and preserved the consistency of the yogurt during the storage. In conclusion, BSGPs in yogurt improved and preserved the textural properties, consistency, acidity and lactic acid bacteria.

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Protease-extracted preserve the flow behavior of yogurt

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Protease-extracted soften the microstructural surface of the matrices

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BSG protein-rich extracts improve the survival of lactic acid bacteria

Recent trends in aroma release and perception during food oral processing: A review

The dynamic and complex peculiarities of the oral environment present several challenges for controlling the aroma release during food consumption. They also pose higher requirements for designing food with better sensory quality. This requires a comprehensive understanding of the basic rules of aroma transmission and aroma perception during food oral processing and its behind mechanism. This review summarized the latest developments in aroma release from food to retronasal cavity, aroma release and delivery influencing factors, aroma perception mechanisms. The individual variance is the most important factor affecting aroma release and perception. Therefore, the intelligent chewing simulator is the key to establish a standard analytical method. The key odorants perceived from the retronasal cavity should be given more attention during food oral processing. Identification of the olfactory receptor activated by specific odorants and its binding mechanisms are still the bottleneck. Electrophysiology and image technology are the new noninvasive technologies in elucidating the brain signals among multisensory, which can fill the gap between aroma perception and other senses. Moreover, it is necessary to develop a new approach to integrate the relationship among aroma binding parameters, aroma concentration, aroma attributes and cross-modal reactions to make the aroma prediction model more accurate.

Nutritional and sensory properties of low-fat milk dessert enriched with quinoa (Chenopodium quinoa Willd) Titicaca protein isolate

The purpose of this work was to investigate the potential production of Titicaca quinoa protein isolated (TQPI) to improve the quality of low-fat desserts. In this study, low-fat desserts incorporating TQPI (0, 1%, 3%, and 5%) were produced. The results indicated that as TQPI increased, protein content, acidity, b*, hardness, and water-holding capacity (WHC) increased. Dessert containing 5% TQPI exhibited the highest values of hardness (63.23 ± 1.46 g), adhesiveness (0.88 ± 0.19), gumminess (67.30 ± 1.41 g), chewiness (11.41 ± 0.46 mJ), protein content (18.09%), b*(20.75), WHC (50.65%), and acidity (25.9 °D) on the 21st day of the storage time. TQPI (1%) gave a better effect on taste, texture, and total acceptability in comparison with other fortified desserts. Electron microscopy shows that the fortified dessert containing 5% TQPI had a stronger network than the others. It can be concluded that desserts containing 1% TQPI presented a very good response as a potential new dairy product based on sensory properties.

Satiety and consumers' perceptions: What opinions do Argentinian and Brazilian people have about yogurt fortified with dairy and legume proteins?

This study (1) evaluated the perceptions of Argentinian and Brazilian consumers regarding yogurt fortified with dairy proteins, legume proteins, or a combination of both, and (2) determined the satiety expectations of these foods as well as the consumers' intentions to taste and purchase protein-fortified yogurt. A total of 298 Argentinian and 100 Brazilian participants completed an online survey for this study. The free word association technique was used to investigate their perceptions about "satiety" as a verbal stimulus and 6 concepts of yogurt as visual/verbal stimuli (yogurt, set yogurt, skim set yogurt, skim set yogurt with a high content of dairy proteins, skim set yogurt with a high content of legume proteins, and skim set yogurt with a mix of dairy and legume proteins). The expected satiation and intentions to taste or purchase were evaluated using categorical scales. Regardless of their cultural background, participants from both countries expressed similar associations with the stimuli presented. Yogurt and set yogurt were associated with consumption occasions, sensory characteristics, liking, and foods, whereas skim yogurt was associated with diet food. Products fortified with proteins were associated with healthy foods, regardless of the protein source, and they yielded the highest rates for expected satiation. Brazilian participants were more likely to taste the food with a combination of proteins; however, participants from both countries were indifferent to purchasing the product. Important characteristics in the design and marketing of these products were pleasant sensations, such as "fullness," "satisfied," and snacks to eat "on the go," and the vegetarian consumers' segment. The combination with fruits or cereals, creaminess, and vanilla flavor should also be considered. The study findings could have implications for the dairy industry when designing yogurt fortified with proteins and communicating the nutritional and wholesome properties of these products.

Milk Protein-Based Nanohydrogels: Current Status and Applications

Milk proteins are excellent biomaterials for the modification and formulation of food structures as they have good nutritional value; are biodegradable and biocompatible; are regarded as safe for human consumption; possess valuable physical, chemical, and biological functionalities. Hydrogels are three-dimensional, cross-linked networks of polymers capable of absorbing large amounts of water and biological fluids without dissolving and have attained great attraction from researchers due to their small size and high efficiency. Gelation is the primary technique used to synthesize milk protein nanohydrogels, whereas the denaturation, aggregation, and gelation of proteins are of specific significance toward assembling novel nanostructures such as nanohydrogels with various possible applications. These are synthesized by either chemical cross-linking achieved through covalent bonds or physical cross-linking via noncovalent bonds. Milk-protein-based gelling systems can play a variety of functions such as in food nutrition and health, food engineering and processing, and food safety. Therefore, this review highlights the method to prepare milk protein nanohydrogel and its diverse applications in the food industry.

An insight into the health beneficial of probiotics dairy products: a critical review

Probiotic dairy products satisfy people's pursuit of health, and are widely favored because of their easy absorption, high nutritional value, and various health benefits. However, its effectiveness and safety are still controversial. This proposal aims to analyze the effect of probiotics on the quality characteristics of dairy products, clarify a series of physiological functions of probiotic dairy products and critically evaluate the effectiveness and safety of probiotic dairy products. Also, dairy products containing inactivated microorganisms were compared with probiotic products. The addition of probiotics enables dairy products to obtain unique quality characteristics, and probiotic dairy products have better health-promoting effects. This review will promote the further development of probiotic dairy products, provide directions for the research and development of probiotic-related products, and help guide the general public to choose and purchase probiotic fermentation products.

Genomic Insight Into Lacticaseibacillus paracasei SP5, Reveals Genes and Gene Clusters of Probiotic Interest and Biotechnological Potential

The Lacticaseibacillus paracasei species is comprised by nomadic bacteria inhabiting a wide variety of ecological niches, from fermented foodstuffs to host-associated microenvironments. Lc. paracasei SP5 is a novel strain, originally isolated from kefir grains that presents desirable probiotic and biotechnological attributes. In this study, we applied genomic tools to further characterize the probiotic and biotechnological potential of the strain. Firstly, whole genome sequencing and assembly, were performed to construct the chromosome map of the strain and determine its genomic stability. Lc. paracasei SP5 carriers several insertion sequences, however, no plasmids or mobile elements were detected. Furthermore, phylogenomic and comparative genomic analyses were utilized to study the nomadic attributes of the strain, and more specifically, its metabolic capacity and ability to withstand environmental stresses imposed during food processing and passage through the gastrointestinal (GI) tract. More specifically, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Carbohydrate-active enzyme (CAZymes) analyses provided evidence for the ability of the stain to utilize an array of carbohydrates as growth substrates. Consequently, genes for heat, cold, osmotic shock, acidic pH, and bile salt tolerance were annotated. Importantly bioinformatic analysis showed that the novel strain does not harbor acquired antimicrobial resistance genes nor virulence factors, in agreement with previous experimental data. Putative bacteriocin biosynthesis clusters were identified using BAGEL4, suggesting its potential antimicrobial activity. Concerning microbe-host interactions, adhesins, moonlighting proteins, exopolysaccharide (EPS) biosynthesis genes and pilins mediating the adhesive phenotype were, also, pinpointed in the genome of Lc. paracasei SP5. Validation of this phenotype was performed by employing a microbiological method and confocal microscopy. Conclusively, Lc. paracasei SP5 harbors genes necessary for the manifestation of the probiotic character and application in the food industry. Upcoming studies will focus on the mechanisms of action of the novel strain at multiple levels.

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.

In vivo and in vitro aroma release in surimi gel with different cross-linking degrees by proton transfer reaction-mass spectrometry

Transglutaminase-induced cross-linking has been suggested as a strategy to govern surimi gels' texture. To achieve the aroma regulation of surimi gels by cross-links, surimi gels were treated with microbial transglutaminase to get different cross-linking degrees, and in vivo and in vitro aroma releases were investigated by a proton transfer reaction-mass spectrometry (PTR-MS). Seventeen compounds in surimi gels were detected by PTR-MS. The in vitro release curves of odorants were fitted by a pseudo-first-order kinetics model. As the cross-links increased, most aroma compounds' released concentrations and release rates decreased first, and then increased significantly (P < 0.05) when the cross-linking degree exceed around 35.4%, negatively related to the springiness and the gel strength of surimi gels. However, the in vivo aroma release results showed that the harder surimi gel released fewer aroma compounds. In conclusion, texture affected by cross-links could be a strategy to control the aroma release of surimi gels.

Influence of Fat Replacers on the Rheological, Tribological, and Aroma Release Properties of Reduced-Fat Emulsions

Reduced-fat food products can help manage diet-related health issues, but consumers often link them with poor sensory qualities. Thus, high-quality fat replacers are necessary to develop appealing reduced-fat products. A full-fat model emulsion was reduced in fat by replacing fat with either water, lactose, corn dextrin (CD), inulin, polydextrose, or microparticulated whey protein (MWP) as fat replacers. The effect of fat reduction and replacement, as well as the suitability of different types of fat replacers, were determined by analyzing fat droplet size distribution, composition, rheological and tribological properties, and the dynamic aroma release of six aroma compounds prevalent in cheese and other dairy products. None of the formulations revealed a considerable effect on droplet size distribution. MWP strongly increased the Kokini oral shear stress and viscosity, while CD exhibited similar values to the full-fat emulsion. All four fat replacers improved the lubricity of the reduced-fat samples. Butane-2,3-dione and 3-methylbutanoic acid were less affected by the changes in the formulation than butanoic acid, heptan-2-one, ethyl butanoate, and nonan-2-one. The aroma releases of the emulsions comprising MWP and CD were most similar to that of the full-fat emulsion. Therefore, CD was identified as a promising fat replacer for reduced-fat emulsions.

Bacterial Communities in Lanna Phak-Gard-Dong (Pickled Mustard Green) from Three Different Ethnolinguistic Groups in Northern Thailand

The Lanna region, the main part of northern Thailand, is a place of ethnic diversity. In this study, we investigated phak-gard-dong (PGD), or pickled mustard green (Brassica juncea L. Czern.), for its beneficial bacteria content and to analyse the variations in bacterial compositions among the PGD of three different ethnolinguistic groups, the Karen, Lawa, and Shan. DNA was extracted from the PGD pickled brine, and 16S rRNA gene Illumina sequencing was performed. Metagenomic data were analysed and the results demonstrated that the dominant bacterial species were Weissella (54.2%, 65.0%, and 10.0%) and Lactobacillus (17.5%, 5.6%, and 79.1%) in the PGD of the Karen, Lawa, and Shan, respectively. Pediococcus was found only in the PGD of the Karen and Shan. Bacterial communities in PGD of the Lawa were distinctive from the other ethnic groups, both in the alpha and beta diversity, as well as the predicted functions of the bacterial communities. In addition, overall network analysis results were correlated to bacterial proportions in every ethnic PGD. We suggest that all ethnic PGDs have the potential to be a good source of beneficial bacteria, warranting its conservation and further development into health food products.

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.

Non-Fat Yogurt Fortified with Whey Protein Isolate: Physicochemical, Rheological, and Microstructural Properties

The demand for low- and non-fat products has recently increased due to the health problems, such as obesity, diabetes, and cardiovascular diseases, that have resulted from high-fat products. However, the reduction in fat can affect the quality of products adversely. The objective of this work was to explore the potential of whey protein isolate (WPI) in improving the quality of non-fat yogurt prepared using skim milk powder (SMP). Yogurt mixes (standardized at 14% total solids) were formulated using SMP as a milk base enriched with WPI. The SMP was replaced by WPI in the yogurt mixes at a rate of 3, 5, 7, and 9%. Full-fat and non-fat set-style yogurts were prepared from whole milk and skim milk, respectively, as controls. Yogurts were fermented at 43 °C to get a pH of 4.6 and stored at 4 °C for the next day. The texture, microstructure, rheological characteristics, and sensory properties of the yogurt samples were studied. The incorporation of WPI increased the water holding capacity to 50% as compared to the non-fat control. This improved the rheological properties while the yogurt viscosity increased in direct proportion with increasing the WPI. The firmness of yogurt was inversely proportional to the increase in WPI, which resulted in 180 g firmness when 9% WPI was added to the non-fat yogurt formulations. Yogurts’ microstructure improved by the addition of WPI. The non-fat yogurt incorporated with 3 and 7% WPI had comparable sensory and textural characteristics to the full-fat yogurt. WPI can be used as a fat replacer to develop low-fat yogurt with desired features. WPI may be a natural and economical ingredient for producing low- and non-fat fermented dairy food products.

Smoothing temperature and ratio of casein to whey protein: Two tools to improve nonfat stirred yogurt properties

Consumers are not always ready to compromise on the loss of texture and increased syneresis that nonfat stirred yogurts display compared with yogurts that contain fat. In this study, we investigated milk protein composition and smoothing temperature as a means to control nonfat yogurt microstructure, textural properties, and syneresis. Yogurts were prepared with different ratios of casein to whey protein (R1.5, R2.8, and R3.9). Yogurts were pumped through a smoothing pilot system comprising a plate heat exchanger set at 15, 20, or 25°C and then stored at 4°C until analysis (d 1, 9, and 23). Yogurt particle size and firmness were measured. Yogurt syneresis and water mobility were determined, respectively, by centrifugation and time domain low-frequency proton nuclear magnetic resonance (¹H-LF-NMR). Increasing the smoothing temperature increased gel firmness and microgel (dense protein aggregates) sizes independently of the whey protein content. Also, yogurt microgel sizes changed with storage time, but the evolution pattern depended on protein ratio. Yogurt R1.5 showed the largest particles, and their sizes increased with storage, whereas R2.8 and R3.9 had smaller microgels, and R3.9 did not show any increase in microgel size during storage. Micrographs showed a heterogeneous gel with the empty area occupied by serum for R1.5, whereas R2.8 and R3.9 showed fewer serum zones and a more disrupted gel embedding microgels. Induced syneresis reduced with greater whey protein content and time of storage. This is in agreement with ¹H-LF-NMR showing less bulk water mobility with increasing whey protein content during storage. However, ¹H-LF-RMN revealed higher values of spontaneous serum separation during storage for R1.5 and R3.9 yogurts, whereas these were lower and stable for R2.8 yogurt. Microgels play an important structural role in yogurt textural attributes, and their characteristics are modulated by whey protein content and smoothing temperature. Optimization of these parameters may help improve nonfat stirred dairy gel.

Influence of a prebiotic and natural sweeteners on the sensory profile of skyr yogurt with mango pulp

Skyr yogurts have been gaining prominence because of their different sensory characteristics. Due to their healthy appeal, the use of natural sweeteners to replace sucrose in this type of yogurt can be an alternative for incorporating a sweet taste, in addition to increasing the functionality of the product through the incorporation of prebiotics. This study aimed to determine whether the addition of fructooligosaccharide (FOS), sucrose, stevia, and thaumatin affects the sensory profile of the skyr yogurt with mango pulp and its acceptance in two Brazilian regions. Eight formulations of skyr with mango pulp were developed. The compositional parameters evaluated were moisture, protein, lipids, ash, and carbohydrate. The tests performed were ideal sweetness and mango flavor, sweetness equivalence for each sweetener used, Quantitative Descriptive Analysis (QDA), and consumer testing in the Southeast and Northeast regions of Brazil. In general, the addition of FOS did not impact the characteristics of the formulated skyr yogurt. The type of sweetener had an impact on the sensory profile and acceptance of the skyr yogurt, affected characteristics such as mango flavor, sweet taste, sweet aftertaste, bitter taste, bitter aftertaste, and metallic flavor. The results of the affective test demonstrated that, for consumers in the Southeast, mango flavor is a positive attribute in this yogurt, and for Northeastern consumers, in addition to mango flavor, sweetness must also be taken into consideration. PRACTICAL APPLICATION: This study may be useful for the dairy industry because in the literature, there is still a lack of sensory studies of skyr yogurt, especially when sucrose substitutes are used. The results of the consumer test in this work reinforce the importance of studies related to consumer preferences with cultural differences.

Review on fat replacement using protein-based microparticulated powders or microgels: A textural perspective

Background

Due to the growing rise in obesity and food-linked diseases, the replacement of calorie-dense fat has been a key focus of food industries in the last few decades with proteins being identified as promising fat replacers (FRs).

Scope and approach

This review aims to provide an overview of animal and plant protein-based FR studies that have been performed in the last 5 years. Protein isolates/concentrates, their microparticulated forms and protein microgels in model and real foods have been examined. Special emphasis has been given on the characterisation techniques that have been used to compare the full fat (FF) and low fat (LF) versions of the foods using FRs.

Key findings and conclusions

Microparticulated whey protein (MWP) has been the preferred choice FR with some success in replacing fat in model foods and dairy applications. Plant proteins on the other hand have attracted limited research attention as FRs, but show success similar to that of animal proteins. Key characterisation techniques used to compare full fat with low fat products containing FRs have been apparent viscosity, texture profile analysis, microscopy, particle size and sensory properties with oral tribology being a relatively recent undertaking. Coupling tribology with adsorption techniques (muco-adhesion) can be effective to bridge the instrumental-sensory property gap and might accelerate the development cycle of designing low/no fat products. From a formulation viewpoint, sub-micron sized microgels that show shear-thinning behaviour and have boundary lubrication properties offer promises with respect to exploiting their fat replacement potential in the future.

Changes in the Physicochemical Parameters of Yoghurts with Added Whey Protein in Relation to the Starter Bacteria Strains and Storage Time

Simple Summary

Addition of whey proteins to yoghurt may be a good solution that could be routinely applied in the dairy industry to offer consumers a new functional product, with health-promoting properties. Conducting a comprehensive analysis of yoghurts made using two different starter cultures, with and without the addition of various levels of whey proteins, we found that the quality of yoghurts with WPC, including sensory quality, can be satisfactory for even 28 days of storage. The use of whey protein concentrate determined both the physicochemical (i.e., lactic acid content, proximate chemical composition, water holding capacity, water activity, firmness, consistency, cohesive strength and colour parameters) and sensory quality of the yoghurts. The additive had a significant effect on potential acidity, inhibiting the increase in the amount of lactic acid in yoghurts during storage, and also reduced syneresis. We suggest that using WPC on a larger scale will create new opportunities on the food market.

Abstract

The stability of the physicochemical characteristics of yoghurts during refrigerated storage is important for industry and the consumer. In this study we produced plain yoghurts with the addition of health-promoting whey protein concentrate (WPC), using two different starter cultures based on Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. Physicochemical changes (acidity, nutritional value, water activity, water-holding capacity, texture, and colour, including whitening and yellowing indices) as well as sensory changes occurring during 28-day refrigerated storage were determined. Starter cultures were found to significantly (p ≤ 0.05 and p ≤ 0.01) influence the water-holding capacity, firmness, consistency, cohesive strength and colour parameters of the curd. Use of whey protein concentrate affected both the physicochemical and sensory quality of the yoghurts. The additive had a significant effect on potential acidity, inhibiting the increase in lactic acid in the yoghurts during storage, and also reduced syneresis. However, it decreased the lightness of curd and negatively affected its sensory characteristics, primarily flavour. Moreover, nearly all parameters changed significantly with the passage of storage time (in most cases negatively). The exceptions were total protein and fat content. The changes, however, were not severe and remained at a level acceptable to tasters. Addition of 1% or 2% whey protein to yoghurt may be a good solution that can be routinely applied in the dairy industry to offer consumers a new functional product. A comprehensive assessment of the physicochemical and sensory changes occurring during refrigerated storage of yoghurts manufactured with the addition of WPC and using different cultures is crucial for modelling such a product.

Impact of High-Pressure Process on Probiotics: Viability Kinetics and Evaluation of the Quality Characteristics of Probiotic Yoghurt

The impact of high-pressure (HP) processing on the viability of two probiotic microorganisms (Bifidobacterium bifidum and Lactobacillus casei) at varying pressure (100−400 MPa), temperature (20−40 °C) and pH (6.5 vs. 4.8) conditions was investigated. Appropriate mathematical models were developed to describe the kinetics of the probiotics viability loss under the implemented HP conditions, aiming to the development of a predictive tool used in the design of HP-processed yoghurt-like dairy products. The validation of these models was conducted in plain and sweet cherry-flavored probiotic dairy beverage products pressurized at 100−400M Pa at ambient temperature for 10 min. The microbiological, rheological, physicochemical and sensory characteristics of the HP-treated probiotic dairy beverages were determined in two-week time intervals and for an overall 28 days of storage. Results showed that the application of HP in the range of 200−300 MPa had minimal impact on the probiotic strains viability throughout the entire storage period. In addition, the aforementioned HP processing conditions enhanced the rheological and sensory properties without affecting post-acidification compared to the untreated product analogues.