Identifying Key Attributes for Protein Beverages

Effects of plant polyphenols on lipid oxidation in pea and soy protein solutions

Significant lipid-derived off-flavors hinder broader acceptance and applicability of plant protein ingredients. Polyphenols are strong antioxidants and can react with protein and carbonyl compounds to reduce oxidative off-flavor development. The effects of polyphenols (catechin, tannic acid (TA), grape seed extract (GSE), and green tea extract (GTE)) on lipid oxidation in pea and soy protein solutions were investigated. All polyphenols reduced lipid oxidation products and volatile compound concentration versus their respective controls. TA, GSE, and GTE reduced the secondary products in pea and soy proteins by an average of 75 % and 50 %, respectively, versus controls, compared to catechin's 61 % and 13 %, respectively. The chemical structures of TA, GSE, and GTE likely allowed them to interact more effectively than catechin with proteins, especially lipoxygenase. However, no significant differences between the polyphenols' antioxidant capacities were observed. Thus, polyphenols predominantly reduced lipid oxidation via interactions with proteins, rather than electron transfer or radical quenching.

Milk beverage base with lactose removed with ultrafiltration: Effect of fat and protein concentration on sensory and physical properties

Our objectives were to determine the effect of fat (skim to whole milk) and protein (3.4%-10.5%) concentration on the sensory and physical properties of milk beverage base that had lactose and other low molecular components removed by ultrafiltration (UF). In experiment 1, a matrix of 16 treatments was produced to achieve 4 levels of lactose removal (0%, 30%, 70%, and 97%) at each of 4 fat levels (skim, 1%, 2%, and whole milk). In experiment 2, a matrix of 12 treatments was produced to achieve 4 levels of lactose removal (0%, 30%, 70%, and 97%) at each of 3 protein concentrations (3.4%, 6.5%, and 10.5% protein). Physical and sensory properties of these products were determined. Removal of >95% of milk lactose by UF required a diafiltration volume of approximately 3 times the milk volume. Lactose and low molecular weight solute removal increased whiteness across the range from skim to whole milk while decreasing viscosity and making milk flavor blander. In addition, lactose (and other low molecular weight solute) removal by UF decreased titratable acidity by more than 50% and increased milk pH at 20°C to >7.0. Future work on milk and milk-based beverages with lactose removed by UF needs to focus on interaction of the remaining milk solids with added flavorings, changing casein to whey protein ratio before removal of lactose by UF, and the effect of lactose and low molecular weight solute removal on heat stability, particularly for neutral-pH, shelf-stable milk-based beverages.

Sensory Analysis and Consumer Preference: Best Practices

Sensory science is a multidisciplinary field that encompasses a wide variety of established and newly developed tests to document human responses to stimuli. Sensory tests are not limited to the area of food science but they find wide application within the diverse areas of the food science arena. Sensory tests can be divided into two basic groups: analytical tests and affective tests. Analytical tests are generally product-focused, and affective tests are generally consumer-focused. Selection of the appropriate test is critical for actionable results. This review addresses an overview of sensory tests and best practices.

Physical and sensory properties of lemon-flavored acidic beverages formulated with nonfat dry milk during storage

Sensory and physical properties of 2 lemon-flavored beverages with 5% and 7.5% wt/wt nonfat dry milk (NFDM) at pH 2.5 were studied during storage. The 2 beverages had similar volatile compounds, but the 5% NFDM had higher aroma and lemon flavor, with a preferred appearance by consumers due to the lower turbidity and viscosity. After 28 d of storage at 4°C, lemon flavor decreased in the 5% NFDM beverage but was still more intense than the 7.5% one. During 70 d of storage, no microorganisms were detected, and the beverages were more stable when stored at 4°C than at room temperature according to changes of physical properties measured for appearance, turbidity, color, particle size, zeta potential, rheological properties, and transmission electron microscopy morphology. Findings of the present study suggest that NFDM may be used at 5% wt/wt to produce stable acidic dairy beverages with low turbidity when stored at 4°C.

Effect of Hydrothermal Cooking Combined with High-Pressure Homogenization and Enzymatic Hydrolysis on the Solubility and Stability of Peanut Protein at Low pH

A novel method combining high-pressure homogenization with enzymatic hydrolysis and hydrothermal cooking (HTC) was applied in this study to modify the structure of peanut protein, thus improving its physicochemical properties. Results showed that after combined modification, the solubility of peanut protein at a pH range of 2–10 was significantly improved. Moreover, the Turbiscan stability index of modified protein in the acidic solution was significantly decreased, indicating its excellent stability in low pH. From SDS-PAGE (Sodium Dodecyl Sulfate PolyAcrylamide Gel Electrophoresis), the high molecular weight fractions in modified protein were dissociated and the low molecular weight fractions increased. The combined modification decreased the particle size of peanut protein from 74.82 to 21.74 μm and shifted the isoelectric point to a lower pH. The improvement of solubility was also confirmed from the decrease in surface hydrophobicity and changes in secondary structure. This study provides some references on the modification of plant protein as well as addresses the possibility of applying peanut protein to acidic beverages.

Do the Colors of the Label and the Sweetening Agent Information Influence the Sensory Expectations Consumer? A Case Study with Skyr-Type Yogurt

The objective of this research was to evaluate the sensory expectation and buying intention of consumers from different Brazilian regions for skyr-type yogurt based on the colors and sweetener on its label. Ten images of skyr mango yogurt labels were created varying in color (orange, white, yellow, blue, and green) and sweetening agent (sucrose and natural sweeteners). Consumers (151 consumers) were asked to rate their expectation for the ideal of sweetness, healthiness, acceptance, and buying intention. Labels containing the information “sweetened with sucrose” had a higher percentage of expectation of sweeter than ideal. Label color and sweetening agent had a significant effect on the expectation of acceptance, with a higher percentage for yogurt sweetened with natural sweeteners. There were not statistical differences (p > 0.05) between the labels regarding expected healthiness. Results also showed that consumers had a low level of familiarity with skyr-type yogurts, but it is presented as a healthy yogurt alternative.

Consumer perception of natural hot-pepper cheeses

Hot-pepper cheese (HPC) is a growing category of flavored natural cheese. The objective of this study was to evaluate consumer perception of HPC using a combination of quantitative survey methods and consumer evaluation of HPC. An online survey (n = 510) was conducted to understand drivers of purchase for the HPC category. Consumers of HPC answered maximum difference exercises and an adaptive choice-based conjoint activity focused on HPC attributes. Subsequently, natural HPC were manufactured in duplicate with 5 different hot-pepper blends with a range of heat intensities and distinct color differences. Trained panel profiling and consumer-acceptance testing (n = 194 consumers) were conducted on the cheeses. Three clusters of consumers were identified from the online survey. Cluster 1 (n = 175) were traditional HPC consumers, and cluster 2 (n = 152) preferred milder HPC. Cluster 3 (n = 183) showed preference for spicier HPC as well as novel HPC, such as those made with habanero peppers or white Cheddar cheese. Conceptually, the overall ideal HPC was a Monterey Jack with medium-sized, multicolored pieces of jalapeno peppers and a medium heat and spiciness. Heat and spiciness intensity and type of cheese were the most important attributes. The 5 HPC used in consumer testing had a distinct range (low to high) of hot-pepper burn and heat intensity by trained panel profiling. Consumer overall liking increased as hot-pepper burn and heat intensity increased to a certain point, indicating HPC consumers may have an optimal point for heat and spiciness in HPC. Consumers also preferred HPC with multicolored pepper pieces over those with a single pepper color, consistent with survey results. Consumers who self-reported that they prefer mild- or medium-spicy foods (mild consumers) preferred HPC that were less intense in hot-pepper burn than consumers who self-reported preference for hot or spicy foods (hot consumers). Most HPC consumers preferred HPC with higher heat intensity and were also motivated by visual characteristics of HPC.

Chemical and sensorial characterization of Tejate, a Mexican traditional maize-cocoa beverage, and improvement of its nutritional value by protein addition

Tejate is a Mexican traditional beverage elaborated with nixtamalized maize (Zea mays L.), cocoa (Theobroma cacao L.) beans, cacao flowers (Quararibea funebris), and mamey sapota fruit seeds (Pouteria sapota) that is considered a refreshing drink with satiety properties. Local formulations show a high content of minerals, but a relatively low protein content. The aim of this study was to identify a standardarized formulation but conserving physicochemical and sensorial ethnic identity of traditional Tejate, and to improve its nutritional value with the addition of protein without modifying its sensorial profile. A 2^4-1 fractional factorial design with central point was used to vary ingredients concentration and the amount of ash used for maize nixtamalization instead of lime (calcium hydroxide) was 75 g/100 g (w/w) of wood ashes in 2 L water. The standardized traditional formulation (TF) was selected through a sensory analysis with an expert panel: 20 g of cacao flowers, 30 g of mamey sapota fruit seeds, and 100 g of cocoa beans per kg of maize nixtamalized with 6% of ash. Whey protein concentrate (80% of protein) or soy protein isolate (88% of protein) were added to the TF at 1, 2, and 2.5%. The addition of 1% soy protein isolate increased TF protein content without modifying its physicochemical parameters, and improved the beverage stability during cold storage. The protein-rich Tejate formulation could be used as a functional beverage maintaining its ethnic identity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05073-w.

Invited review: Sustainability: Different perspectives, inherent conflict

Consumer definitions of sustainability are largely uninformed by scientific research and may not align with industry definitions. Furthermore, consumers themselves have varied perceptions, definitions, and opinions of sustainability that vary between categories and products within the dairy category. Understanding these differences and developing marketing messaging aligned with consumer sustainability definitions offer an advantage to dairy product producers when strategically positioning their products in a changing marketplace. This review outlines the factors that may affect consumer sustainability perceptions to provide a basis for future marketing and scientific work. Consumer trends and desires for sustainability are explored, including how they are reflected in the rapid growth of plant-based alternatives. Factors that may influence consumer perception of dairy as sustainable are covered in detail, including packaging, labeling, animal welfare, organic status, grass-fed or pasture-raised feeding systems, and local and clean label perceptions. Finally, a discussion of the challenges of marketing dairy foods with sustainability messages is addressed.

Ready-to-drink protein beverages: Effects of milk protein concentration and type on flavor

This study evaluated the role of protein concentration and milk protein ingredient [serum protein isolate (SPI), micellar casein concentrate (MCC), or milk protein concentrate (MPC)] on sensory properties of vanilla ready-to-drink (RTD) protein beverages. The RTD beverages were manufactured from 5 different liquid milk protein blends: 100% MCC, 100% MPC, 18:82 SPI:MCC, 50:50 SPI:MCC, and 50:50 SPI:MPC, at 2 different protein concentrations: 6.3% and 10.5% (wt/wt) protein (15 or 25 g of protein per 237 mL) with 0.5% (wt/wt) fat and 0.7% (wt/wt) lactose. Dipotassium phosphate, carrageenan, cellulose gum, sucralose, and vanilla flavor were included. Blended beverages were preheated to 60°C, homogenized (20.7 MPa), and cooled to 8°C. The beverages were then preheated to 90°C and ultrapasteurized (141°C, 3 s) by direct steam injection followed by vacuum cooling to 86°C and homogenized again (17.2 MPa first stage, 3.5 MPa second stage). Beverages were cooled to 8°C, filled into sanitized bottles, and stored at 4°C. Initial testing of RTD beverages included proximate analyses and aerobic plate count and coliform count. Volatile sulfur compounds and sensory properties were evaluated through 8-wk storage at 4°C. Astringency and sensory viscosity were higher and vanillin flavor was lower in beverages containing 10.5% protein compared with 6.3% protein, and sulfur/eggy flavor, astringency, and viscosity were higher, and sweet aromatic/vanillin flavor was lower in beverages with higher serum protein as a percentage of true protein within each protein content. Volatile compound analysis of headspace vanillin and sulfur compounds was consistent with sensory results: beverages with 50% serum protein as a percentage of true protein and 10.5% protein had the highest concentrations of sulfur volatiles and lower vanillin compared with other beverages. Sulfur volatiles and vanillin, as well as sulfur/eggy and sweet aromatic/vanillin flavors, decreased in all beverages with storage time. These results will enable manufacturers to select or optimize protein blends to better formulate RTD beverages to provide consumers with a protein beverage with high protein content and desired flavor and functional properties.

Influence of Age and Individual Differences on Mouthfeel Perception of Whey Protein-Fortified Products: A Review

Protein needs are considered to increase with age, with protein consumption being associated with many positive outcomes. Protein-fortified products are often used to improve nutritional status and prevent age-related muscle mass loss in older adults. Accordingly, older adults are commonly provided with products fortified with whey protein; however, such products can cause mouthdrying, limiting consumption and product enjoyment. Currently, the extent to which age and individual differences (e.g., saliva, oral health, food oral processing) influence the perception of whey protein-derived mouthdrying is relatively unclear. Previous research in this area has mainly focused on investigating mouthdrying, without taking into account individual differences that could influence this perception within the target population. Therefore, the main focus of this review is to provide an overview of the relevant individual differences likely to influence mouthfeel perception (specifically mouthdrying) from whey protein-fortified products, thereby enabling the future design of such products to incorporate better the needs of older adults and improve their nutritional status. This review concludes that age and individual differences are likely to influence mouthdrying sensations from whey protein-fortified products. Future research should focus more on the target population and individual differences to maximise the benefits from whey protein fortification.

Sugar Reduction in Dairy Food: An Overview with Flavoured Milk as an Example

Owing to the public health concern associated with the consumption of added sugar, the World Health Organization recommends cutting down sugar in processed foods. Furthermore, due to the growing concern of increased calorie intake from added sugar in sweetened dairy foods, the present review provides an overview of different types and functions of sugar, various sugar reduction strategies, and current trends in the use of sweeteners for sugar reduction in dairy food, taking flavoured milk as a central theme where possible to explore the aforementioned aspects. The strength and uniqueness of this review are that it brings together all the information on the available types of sugar and sugar reduction strategies and explores the current trends that could be applied for reducing sugar in dairy foods without much impact on consumer acceptance. Among different strategies for sugar reduction, the use of natural non-nutritive sweeteners (NNSs), has received much attention due to consumer demand for natural ingredients. Sweetness imparted by sugar can be replaced by natural NNSs, however, sugar provides more than just sweetness to flavoured milk. Sugar reduction involves multiple technical challenges to maintain the sensory properties of the product, as well as to maintain consumer acceptance. Because no single sugar has a sensory profile that matches sucrose, the use of two or more natural NNSs could be an option for food industries to reduce sugar using a holistic approach rather than a single sugar reduction strategy. Therefore, achieving even a small sugar reduction can significantly improve the diet and health of an individual.

Sensory Profile of Rice-Based Snack (Nuroongji) Prepared from Rice with Different Levels of Milling Degree

Nuroongji is a traditional rice-based snack that is widely consumed in Korea, but there is no reported comprehensive sensory characterization of this popular snack. The objective of this study was to conduct a sensory analysis of Nuroongji made with rice with different degrees of milling. Four different types of Nuroongji samples according to the degree of milling were prepared in the lab and subjected to physiochemical analysis. Descriptive sensory analysis was conducted by a trained panel (n = 8), and a consumer acceptance test was conducted using college students (n = 70). A sensory lexicon describing the flavor and texture characteristics of Nuroongji was developed: it included roasted brown rice, burnt, buckwheat, rice powder, glutinous rice power, and floral. The following texture attributes were evaluated in triplicate: hardness of particles, irregularity of particles, degree of coagulation, number of chews, and residual mouthfeel. Significant differences in flavor and mouthfeel attributes were observed between the Nuroongji samples according to the degree of milling (p < 0.05). Nuroongji made with white rice (N1) had a higher hardness value and less sweetness compared to other samples (p < 0.05). Texture- and mouthfeel-related attributes such as cohesiveness of the mass, irregularity of the surface, and astringency were identified as important characteristics that drive consumer acceptance of Nuroongji products. Findings from this study can provide Nuroongji product developers a valuable insight to extend their market by reformulating the product to be appealing to young consumers.

Role of sweeteners on temporality and bar hardening of protein bars

Protein bars are one product that meet consumer demands for a low-carbohydrate, high-protein food. With such a large market for protein bars, producers need to find the correct texture and sweetness levels to satisfy consumers while still delivering a high-protein, low-carbohydrate bar. In the bar industry, bar hardening is a major concern, and currently the effects of non-nutritive sweeteners on bar hardening is unknown. Due to the negative implications of bar hardening, it is important to investigate the sweetener-protein relationship with bar hardening. The objective of this study was to characterize the effects of sweetener and protein source on flavor, texture, and shelf life of high-protein, low-carbohydrate bars. The iso-sweet concentration of sweeteners (sucralose, sucrose, monk fruit, stevia, and fructose) in pea protein (PP), milk protein (MP) and whey protein isolate (WPI) bars were established using magnitude estimation scaling and 2-alternative forced-choice testing. Descriptive analysis and temporal check-all-that-apply methods were then applied to determine flavor and temporal differences between the protein bars. Finally, an accelerated shelf life study was completed to understand how sweetener and protein types affect the shelf life of protein bars. The 15 protein bars formulated at iso-sweet concentration were all stored at 35°C and 55% humidity for 35 d, and measurements were taken every 7 d, beginning at d 1 (d 1, 7, 14, 21, 28, and 35). Bars made with MP required significantly less sweetener, compared with PP and WPI, to reach equal sweetness. Bars sweetened with stevia or monk fruit had distinct bitter and metallic tastes, and sucralose had a low metallic taste. Bars made with WPI were the most cohesive, and PP and WPI bars were more bitter and metallic compared with MP bars. Bars made with WPI and fructose were initially the hardest, but after d 14 they scored at parity with PP sucrose. There were no significant differences among bars in terms of hardness by d 21. Bars made with WPI were consistently denser at all time points than bars made with PP or MP. Bars made with PP were the driest and least cohesive and had the fastest rate of breakdown in the study. Non-nutritive sweeteners did not have a negative effect on bar hardness in low-carbohydrate, high-protein bars. Findings from this study can be applied to commercially produced protein bars for naturally sweetened bars with different protein types without negative effects on protein bar texture.

Invited review: Astringency in whey protein beverages

Astringency is the sensation of mouth drying and puckering, and it has also been described as a loss of lubrication in the mouth. Astringency is perceived as an increase in oral friction or roughness. Astringency caused by tannins and other polyphenols has been well documented and studied. Whey proteins are popular for their functional and nutritional quality, but they exhibit astringency, particularly under acidic conditions popular in high acid (pH 3.4) whey protein beverages. Acids cause astringency, but acidic protein beverages have higher astringency than acid alone. Whey proteins are able to interact with salivary proteins, which removes the lubricating saliva layer of the mouth. Whey proteins can also interact directly with epithelial tissue. These various mechanisms of astringency limit whey protein ingredient applications because astringency is undesirable to consumers. A better understanding of the causes of whey protein astringency will improve our ability to produce products that have high consumer liking and deliver excellent nutrition.

Comparison of a central location test versus a home usage test for consumer perception of ready-to-mix protein beverages

Ready-to-mix (RTM) whey protein beverages are an expanding product category, and sensory properties strongly affect consumer acceptance and purchase intent. Because consumers themselves prepare RTM whey protein beverages, understanding possible gaps between central location test (CLT) and home usage test (HUT) results is critical. The objectives of this study were to compare results obtained from a CLT and a HUT and to identify the drivers of liking and disliking vanilla-flavored RTM whey protein beverages. Fourteen commercial vanilla-flavored RTM whey protein beverages were rehydrated with spring water at 15% solids (wt/vol) and evaluated by a trained panel (n = 8). Ten representative products were selected for consumer testing. Rehydrated beverages were subsequently evaluated by protein beverage consumers (n = 160) in a CLT. Nine representative products were selected for the HUT. Consumers prepared and evaluated individual beverages over 3 consecutive weeks, trying 3 samples each week. Overall liking and other attributes were scored by consumers in both tests. Data were evaluated by univariate and multivariate statistical analyses. Overall liking scores from the HUT were higher than scores from the CLT. The products with the highest and lowest overall liking scores were consistent between the CLT and HUT. More differences were observed among beverages by CLT compared with HUT when liking was averaged across all consumers. Both methods identified 2 distinct consumer clusters. Fruity flavor and sweet taste were drivers of liking, whereas cardboard flavor and bitter taste were drivers of disliking in both methods. The HUT exclusively identified thickness (viscosity) as a driver of liking and astringency as a driver of disliking. These results suggest that a CLT can be used to differentiate consumer acceptance among vanilla-flavored RTM whey protein beverages. A HUT should be used to provide more intensive insights for mouthfeel and mixing experience-related attributes.

Sensory properties of aqueous dispersions of protein-rich extracts from Chlorella protothecoides at neutral and acidic pH

BACKGROUND

Water-soluble proteins extracted from the heterotrophically cultivated microalga Chlorella protothecoides have been shown to have a good solubility over a broad pH range, which makes them a promising candidate for beverage formulations. This study investigated the sensory properties of dispersions of a protein-rich extract from C. protothecoides at neutral and pH 3.

RESULTS

Sensory acceptance tests of the pure extract revealed an overall low acceptance at pH 7 without sucrose addition. Sensory acceptance was significantly (P ≤ 0.05) increased by lowering the pH to 3 with citric acid, and the addition of 50 g kg^-1 sucrose. Here, overall positive sensory acceptance ratings were achieved up to a protein extract concentration of 40 g kg^-1 . Basic taste evaluations showed only low bitterness scores and no significant (P > 0.05) increase in bitterness with decreasing pH.

CONCLUSION

It is suggested that protein-rich extracts from C. protothecoides have promising sensory properties in beverage formulations. © 2019 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Use of acid whey protein concentrate as an ingredient in nonfat cup set-style yogurt

Acid whey resulting from the production of soft cheeses is a disposal problem for the dairy industry. Few uses have been found for acid whey because of its high ash content, low pH, and high organic acid content. The objective of this study was to explore the potential of recovery of whey protein from cottage cheese acid whey for use in yogurt. Cottage cheese acid whey and Cheddar cheese whey were produced from standard cottage cheese and Cheddar cheese-making procedures, respectively. The whey was separated and pasteurized by high temperature, short time pasteurization and stored at 4°C. Food-grade ammonium hydroxide was used to neutralize the acid whey to a pH of 6.4. The whey was heated to 50°C and concentrated using ultrafiltration and diafiltration with 11 polyethersulfone cartridge membrane filters (10,000-kDa cutoff) to 25% total solids and 80% protein. Skim milk was concentrated to 6% total protein. Nonfat, unflavored set-style yogurts (6.0 ± 0.1% protein, 15 ± 1.0% solids) were made from skim milk with added acid whey protein concentrate, skim milk with added sweet whey protein concentrate, or skim milk concentrate. Yogurt mixes were standardized to lactose and fat of 6.50% and 0.10%, respectively. Yogurt was fermented at 43°C to pH 4.6 and stored at 4°C. The experiment was replicated in triplicate. Titratable acidity, pH, whey separation, color, and gel strength were measured weekly in yogurts through 8 wk. Trained panel profiling was conducted on 0, 14, 28, and 56 d. Fat-free yogurts produced with added neutralized fresh liquid acid whey protein concentrate had flavor attributes similar those with added fresh liquid sweet whey protein but had lower gel strength attributes, which translated to differences in trained panel texture attributes and lower consumer liking scores for fat-free yogurt made with added acid whey protein ingredient. Difference in pH was the main contributor to texture differences, as higher pH in acid whey protein yogurts changed gel structure formation and water-holding capacity of the yogurt gel. In a second part of the study, the yogurt mix was reformulated to address texture differences. The reformulated yogurt mix at 2% milkfat and using a lower level of sweet and acid whey ingredient performed at parity with control yogurts in consumer sensory trials. Fresh liquid acid whey protein concentrates from cottage cheese manufacture can be used as a liquid protein ingredient source for manufacture of yogurt in the same factory.