Taste perception and purchase intent of oil‐in‐water spreads: effects of oil types and salt (NaCl or KCl) concentrations

Associations of sodium intake with heart‐related problems are creating awareness towards reducing sodium. Potassium chloride (KCl), a substitute for sodium chloride (NaCl), has the disadvantage of imparting bitterness at high concentrations. We evaluated physical characteristics, taste perception and purchase intent of KCl and NaCl in oil‐in‐water spreads/emulsions composed by olive, rice bran and soya bean oils. Consumers (N = 300) evaluated saltiness/bitterness of emulsions prepared with 65% oil, and NaCl (0.5% and 1.0%) or KCl (0.75% and 1.5%). Olive oil spreads (104.07–107.43 Pa s) had higher viscosity compared to other spreads (59.16–74.96 Pa s). Type of oil had significant effects on bitterness, overall taste liking and viscosity. Taste liking decreased due to bitterness of olive oil spreads (mean drop=1.72–2.43). Purchase intent was positively associated with saltiness and pH and increased with oil claims (increase = 1.3%–22.1%) compared to sodium claims (increase = 0.0%–12.9%). These findings are useful for understanding taste perception of emulsions.     

Increasing Oil Concentration Affects Consumer Perception and Physical Properties of Mayonnaise‐type Spreads Containing KCl

Reducing sodium intakes remains a global challenge for the food industry. KCl is a potential salt substitute but imparts bitterness when used at high concentrations. Little is known about how oil concentrations (OC) affect consumers’ perception of saltiness and bitterness in emulsion products such as mayonnaise containing KCl. We evaluated consumers’ perception and physical properties of mayonnaise‐type spreads at various oil and tastant (NaCl or KCl) concentrations. Consumers (N = 306) evaluated saltiness, bitterness, overall taste liking (OTL) and purchase intent (PI). Viscosity, pH, water activity, and consistency/texture were also measured. Oil and tastant (NaCl or KCl) concentrations had significant effects on saltiness, viscosity, and pH. As OC increased, saltiness intensity slightly decreased for spreads. Increasing oil concentration increased viscosity. Generally, spreads containing KCl had higher bitterness and pH than spreads containing NaCl. All spreads containing KCl were penalized for being “too bitter.” PI was affected by OTL for all spreads but OC was also a significant factor in the purchase decision of spreads containing NaCl. This study demonstrated that increasing OC affected consumers’ taste perception (saltiness and bitterness) and spreads’ physical properties including pH and viscosity.     

Low-sodium roasted peanuts: effects of salt mixtures (NaCl,KCl and glycine) on consumer perception and purchase intent

The effects of ten treatment combinations of two salts (NaCl, KCl) and glycine were evaluated on low-sodium roasted peanuts. Consumers’ (N = 330, recruited from college campus) liking, emotions, perceived saltiness and bitterness intensity, satisfaction and purchase intent (PI) of peanuts were measured following a balanced incomplete block design (t = 10, k = 3, r = 9, b = 30, λ = 2, e₂ = 0.74). Emotions and PI were evaluated both before and after presenting a low-sodium health benefit message. Sodium content of peanuts was reduced from 140 mg Na/50 g peanuts to 41.67 mg Na/50 g without significantly affecting liking scores and with positive PI over 60%. In general, high bitterness and low saltiness intensity ratings negatively affected liking and satisfaction. Consumers expressed less satisfaction when perceived saltiness intensity was ‘Not Enough’ than when ‘Too Much.’ Based on optimisation analysis, any formulation within the range of 59-100/0-40/0-12.5% NaCl/KCl/Gly- representing a potential 37% sodium reduction past minimum ‘low sodium’ requirements- will yield an acceptable product.     

Use of Consumer Acceptability as a Tool to Determine the Level of Sodium Reduction: A Case Study on Beef Soup Substituted With Potassium Chloride and Soy‐Sauce Odor

In this study, consumer acceptability was considered as a tool of reducing sodium rather than just using it as a final examination of the successfulness of the substitution. This study consisted of 4 experimental steps. First, by gradually reducing the concentrations of NaCl, consumer rejection threshold (CRT) of NaCl in beef soup was examined. Then, the amount of KCl that can increase preference was examined in 2 low sodium beef soups, with sodium concentrations slightly above or below the CRT. Relative saltiness of various KCl and NaCl/KCl mixtures were also measured. Finally, consumers evaluated acceptability and intensities of sensory characteristics for 9 beef soup samples that differed with respect to NaCl content and/or KCl content with/without addition of salty‐congruent odor (soy‐sauce odor). The results showed that in the “above CRT” system, consumer acceptability as well as sensory profile of low sodium beef soup substituted using KCl had similar profile to the control although saltiness was not fully recovered, whereas in the “below CRT” system, consumer acceptability was not recovered using KCl solely as a substitute. Potential of using salty‐congruent odor as a final touch to induce salty taste was observed; however, the results inferred the importance of having almost no artificialness in the odor and having harmony with the final product when using it as a strategy to substitute sodium. Overall, the results of the study implied the importance of considering consumer acceptability when approaching sodium reduction to better understand the potentials of the sodium substitutes and salty‐congruent odor.     

Rejection Thresholds in Solid Chocolate‐Flavored Compound Coating

Abstract: Classical detection thresholds do not predict liking, as they focus on the presence or absence of a sensation. Recently however, Prescott and colleagues described a new method, the rejection threshold, where a series of forced choice preference tasks are used to generate a dose‐response function to determine hedonically acceptable concentrations. That is, how much is too much? To date, this approach has been used exclusively in liquid foods. Here, we determined group rejection thresholds in solid chocolate‐flavored compound coating for bitterness. The influences of self‐identified preferences for milk or dark chocolate, as well as eating style (chewers compared to melters) on rejection thresholds were investigated. Stimuli included milk chocolate‐flavored compound coating spiked with increasing amounts of sucrose octaacetate, a bitter and generally recognized as safe additive. Paired preference tests (blank compared to spike) were used to determine the proportion of the group that preferred the blank. Across pairs, spiked samples were presented in ascending concentration. We were able to quantify and compare differences between 2 self‐identified market segments. The rejection threshold for the dark chocolate preferring group was significantly higher than the milk chocolate preferring group (P= 0.01). Conversely, eating style did not affect group rejection thresholds (P= 0.14), although this may reflect the amount of chocolate given to participants. Additionally, there was no association between chocolate preference and eating style (P= 0.36). Present work supports the contention that this method can be used to examine preferences within specific market segments and potentially individual differences as they relate to ingestive behavior. Practical Application: This work makes use of the rejection threshold method to study market segmentation, extending its use to solid foods. We believe this method has broad applicability to the sensory specialist and product developer by providing a process to identify how much is too much when formulating products, even in the context of specific market segments. We illustrate this in solid chocolate‐flavored compound coating, identifying substantial differences in the amount of acceptable bitterness in those who prefer milk chocolate compared to dark chocolate. This method provides a direct means to answer the question of how much is too much.     

Characterisation of Gouda cheeses based on sensory,analytical and high-field 1H nuclear magnetic resonance spectroscopy determinations: Effect of adjunct cultures and brine composition on sodium-reduced Gouda cheese

This study aimed at the interception of flavour deviations of salt-reduced Gouda-type cheeses, salted in sodium-reduced brines (NaCl + KCl brine) compared with a reference brine (NaCl brine), by the addition of adjunct strains of Lactobacillus helveticus and Lactobacillus paracasei, next to the common mixed-strain starter culture for Gouda. A multiphasic analysis of carbohydrates, organic acids, amino acids, and volatile flavour compounds was performed. After 56 days of ripening, the sensory characteristics of the cheeses were evaluated. Trained taste panel analysis determined some significant differences (P < 0.05) in saltiness, bitterness, texture and preference. The selected chemical fingerprint techniques, combined with multivariate data analysis, could be used to characterise Gouda cheeses that varied in ripening time and to which adjunct cultures were added. The variations were related to proteolysis and metabolic processes during ripening. There were no significant differences in the chemometric results between the reference NaCl-brined cheeses and the NaCl + KCl-brined cheeses.     

Proteolysis and sensory properties of dry-cured bacon as affected by the partial substitution of sodium chloride with potassium chloride

Quadriceps femoris muscle samples (48) from 24 pigs were processed into dry-cured bacon. This study investigated the influence of partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on proteolysis and sensory properties of dry-cured bacon. Three salt treatments were considered, namely, I (100% NaCl), II (60% NaCl, 40% KCl), and III (30% NaCl, 70% KCl). No significant differences were observed among treatments in the proteolysis, which was reflected by SDS–PAGE, proteolysis index, amino acid nitrogen, and peptide nitrogen contents. Furthermore, there were no significant differences in the moisture content between control and treatment II, whereas the moisture content in treatment III was significantly higher (p < 0.05) in comparison with control (treatment I). The sensory analysis indicated that it was possible to reduce NaCl by 40% without adverse effects on sensory properties, but 70% replacement of NaCl with KCl resulted in bacon with less hardness and saltiness and higher (p < 0.05) juiciness and bitterness.     

Factors influencing the production of o/w emulsions stabilized by β-lactoglobulin–pectin membranes

A primary emulsion was prepared by homogenizing 10 wt% corn oil with 90 wt% aqueous β-lactoglobulin solution (0.5 wt% β-lg, pH 3 or 7) using a two-stage high-pressure valve homogenizer. This emulsion was mixed with aqueous pectin (citrus, 59% DE) stock solution (2 wt%, pH 3 or 7) and NaCl solution to yield secondary emulsions with 5 wt% corn oil, 0.225 wt% β-lactoglobulin, 0.2 wt% pectin and 0 or 100 mM NaCl. The final pH of the emulsions was then adjusted (3–8). Primary and secondary emulsions were ultrasonically treated (30 s, 20 kHz, 40% amplitude) to disrupt any flocculated droplets. Secondary emulsions were more stable than primary emulsions at intermediate pHs. Secondary emulsions prepared at pH 7 had smaller particle diameters (0.35 to 6 μm) than those prepared at pH 3 (0.42 to 18 μm) across the whole pH range studied, and also had smaller diameters than the primary emulsions (0.35 to 14 μm). Ultrasound treatment reduced the particle diameter of both primary and secondary emulsions and lowered the rate of creaming. The presence of NaCl screened the charges and thus the electrostatic interaction between biopolymer molecules and primary emulsion droplets. Secondary emulsions were more stable to the presence of 100 mM NaCl at low pHs (3–4) than primary emulsions. This study shows that stable emulsions can be prepared by engineering their interfacial membranes using the electrostatic interaction of natural biopolymers, especially at intermediate pHs where proteins normally fail to function.     

Effects of colorant concentration and ‘natural colour’ or ‘sodium content’ claim on saltiness perception,consumer liking and emotion,and purchase intent of dipping sauces

Natural colorant (no colorant, NC = 0%; moderate colorant, MC = 1.2%; high colorant, HC = 3.6% w/w) and salt (regular salt, RS = NaCl; reduced sodium, ReS = KCl; no salt, NS) were added in mayonnaise‐based dipping sauces to evaluate effects of colorant concentration and ‘natural colorant’ or ‘sodium content’ claim on saltiness expectation, consumer liking and emotion, and purchase intent (PI) of these products. Regardless of the salt type and content, increasing colorant concentration decreased colour liking scores while saltiness expectation tentatively increased as indicated by higher % of ‘too much’ responses for saltiness on a JAR (Just‐About‐Right) scale. At a given salt type and content, liking scores of salty taste decreased with increasing colorant concentration, both before and after the ‘sodium content’ claim was given to consumers. Emotion scores elicited by consuming dipping sauces were affected by colorant concentration. Positive emotions (good, interested, satisfied) decreased while negative emotions (guilty, unsafe, worried) increased with increasing colorant concentration. Statements of ‘natural colorant’ and ‘sodium content’ claim had minimal effects on elicited emotions and PI.     

Using taste-induced saltiness enhancement for reducing sodium in Cheddar cheese: Effect on physico-chemical and sensorial attributes

Reduced sodium Cheddar cheese (RSCC) was prepared by substituting 75% of sodium chloride (NaCl) with potassium chloride (KCl). To mask the inherent bitterness of KCl and to improve the flavour profile of RSCC, hydrolysed vegetable protein (HVP) as flavour enhancer (FE) and adenosine-5′-monophosphate (AMP) as bitter blocker (BB) were used. The study evaluated physico-chemical and sensory attributes of RSCC and changes in these attributes during ripening. Flavour, colour and appearance, saltiness and bitterness scores of both the samples were at par (p < 0.05) throughout the period of ripening, but body and texture scores of RSCC was significantly (p < 0.05) lower. This was probably due to increased casein hydration caused by substitution of sodium by potassium. Water activity (a_w) of RSCC was found to be significantly higher. The study suggested successful use of FE and BB for increasing the flavour profile of RSCC.     

Stability of oil‐in‐water emulsions as influenced by thermal treatment of whey protein dispersions or emulsions

Properties of whey protein concentrate stabilised emulsions were modified by protein and emulsion heat treatment (60–90 °C). All liquid emulsions were flocculated and the particle sizes showed bimodal size distributions. The state and surface properties of proteins and coexisting protein/aggregates in the system strongly determined the stability of heat‐modified whey protein concentrate stabilised emulsions. The whey protein particles of 122–342 nm that formed on protein heating enhanced the stability of highly concentrated emulsions. These particles stabilised protein‐heated emulsions in the way that is typical for Pickering emulsions. The emulsions heated at 80 and 90 °C gelled due to the aggregation of the protein‐coated oil droplets.     

The effect of the pungent sensation elicited by Sichuan pepper oleoresin on the sensory perception of saltiness throughout younger and older age groups

Excessive salt in the diet can pose significant health risks and, therefore, the reduction of salt derived from food is an important issue relating to human nutrition and health. Furthermore, the perception of saltiness will be different among people when considering their innate sensitivity, gender, age, psychological traits and dietary habits. In this study, 31 younger participants and 29 older participants were used as research subjects. A web-based questionnaire survey was used to collect information regarding of socio-demographics, consumption frequency and liking for salty and pungent food, as well as personality traits throughout the younger and the older participants. In addition, the 6-n-propylthiouracil (PROP) ratings were tested by the generalized Labeled Magnitude Scale (gLMS) in the laboratory conditions. The rated difference from control method was used to test the sensitivity differences in the saltiness of NaCl and the pungent sensation elicited by Sichuan pepper oleoresin between the younger and older groups. The results showed that the thresholds were significantly lower in the younger group than in the older group, except for the detection threshold of saltiness. Furthermore, the recognition threshold of saltiness  decreased in the presence of the sub-threshold pungency solution, while, the salty intensity was enhanced in both the younger and older groups when exposed to the slightly pungent solution (0.106 g Sichuan pepper oleoresin/L water solutions) compared to the control (spring water). For the younger group, the enhancement percentage of the salty intensity was between 9.3% and 12.5%, while, at the concentration of 4.05 g/L, the salty-enhancement percentage increased by 6.4% in the older group. In addition, the reduction percentage of NaCl reached a level of up to 34.4% in the younger group and was 4.4% in the older group. The Partial Least Squares Regression (PLSR) results indicated that the percentage change in salty intensity increased when the detection threshold of saltiness, the sensation seeking ratings, and PROP ratings increased. On the contrary, the change decreased when the age, life satisfaction ratings, detection threshold of pungency, and consumption frequency of salty food increased. These findings not only provide new information for the flavor design of salt-reduced food and dishes, but also be valuable to public health as well as economic benefits.     

Rheological and Gelation Properties of Meat Batters Prepared with Three Chloride Salts

The gelation and rheological properties of poultry meat emulsions prepared with three chloride salts (NaCl, KCl, MgCl₂) and 50/50 mixtures of the above salts at isoionic strength (IS = 0.42) were studied. The relationship between shear rate and shear stress for the different raw meat emulsions was found to be nonlinear and followed Bingham pseudoplastic behavior. The yield stress for the emulsion containing only MgCl₂ was significantly lower as compared to all the other treatments. The highest rigidity modulus values obtained during cooking were observed in the NaCl + MgCl₂ treatment followed by the NaCl + KCl, NaCl and KCl. The emulsion containing MgCl₂ only broke down at the initial stages of cooking, exhibiting the destabilizing effect of the magnesium cation.     

Physico chemical,microstructural and sensory characteristics of low‐fat meat emulsion containing aloe gel as potential fat replacer

In this study, a possible use of aloe gel (AG) as a potential fat replacer in the manufacture of low‐fat meat emulsion was investigated. The low‐fat meat emulsions with added AG and vegetable oil (VO) in different proportions [AG7.5 (7.5% AG + 7.5% VO); AG5 (5% AG + 10% VO); AG2.5 (2.5% AG + 12.5% VO)] were compared with full‐fat meat emulsion [Control (15% VO only)]. A substantial fat reduction (P < 0.05) up to 50% as compared to full‐fat control meat emulsion was recorded without compromising other sensory attributes of meat emulsion. Microstructural properties as studied by scanning electron microscopy indicated more homogenous regular emulsion matrix with fewer cracks and more regular shaped oil droplets in AG‐added samples than the control samples.     

Processing and storage effects on the oxidative stability of hemp (Cannabis sativa L.) oil‐in‐water emulsions

Hempseed oil was used to form oil‐in‐water emulsions, and the effect of heating, storage and light on the oxidative stability of the dispersed phase was investigated. Lipid oxidation rate increased following thermal processing and light exposure, whereas oxidation markers remained relatively unaffected during emulsions storage at 4 °C for 10 days. Induction times of the emulsions were reduced up to 26% and the concentration of thiobarbituric acid reactive substances increased up to 4.5‐fold, depending on the processing conditions. Selected berries as potential sources of natural antioxidants were screened for polyphenol and anthocyanin content in order to investigate their ability to retard lipid oxidation in comparison with a commercially available synthetic counterpart. Raspberry powder extract significantly improved the oxidative stability of hemp‐based emulsion compared with the control and was even more effective compared to a synthetic antioxidant when samples were subjected to heat treatment.     

Impact of whey protein isolates and concentrates on the formation of protein nanoparticles‐stabilised Pickering emulsions

Whey protein nanoparticles (NPs) were prepared by heat‐induced method. The influences of whey protein isolates (WPIs) and concentrates (WPCs) on the formation of NPs were first investigated. Then Pickering emulsions were produced by protein NPs and their properties were evaluated. After heat treatment, WPC NPs showed larger particle size, higher stability against NaCl, lower negative charge and contact angle between air and water. Dispersions of WPC NPs appeared as higher turbidity and viscosity than those of WPI NPs. The interfacial tension of WPC NPs (~7.9 mN/m at 3 wt% NPs) was greatly lower than that of WPI NPs (~12.1 mN/m at 3 wt% NPs). WPC NPs‐stabilised emulsions had smaller particle size and were more homogeneous than WPI NPs‐stabilised emulsions. WPC NPs‐stabilised emulsions had higher stability against NaCl, pH and coalescence during storage.     

Comparing effects of α‐ vs. β‐chitosan coating and emulsion coatings on egg quality during room temperature storage

Effects of α‐ and β‐chitosan (CH), soybean oil (SO) and their emulsions (CH:SO = 2:3) as coating materials on selected internal quality and sensory properties of eggs were evaluated during 5 weeks storage at 25 °C. After 3 weeks of storage, α‐ and β‐CH‐coated eggs changed to B grade, while SO‐ and emulsion‐coated eggs preserved grade A quality. Weight loss of eggs coated with SO and CH:SO emulsions was <2.0% vs. 5.3–5.8% for noncoated and CH‐coated eggs after 5 weeks of storage. β‐CH (0.9%) maintained lower weight loss of eggs than α‐CH (1.2%) only at 1‐week storage. Albumen pH of eggs coated with SO and CH:SO emulsions decreased progressively throughout storage. Eggs coated with β‐CH:SO emulsion and SO were significantly glossier than noncoated eggs. Consumers indicated positive purchase intent (69.17–76.67%) for all coated eggs. Overall, α‐CH:SO and β‐CH:SO emulsions extended egg shelf life by at least 3 weeks during room temperature storage.     

Preparation,characterisation and selected functional properties of hydrolysed sodium caseinate–maltodextrin conjugate

Sodium caseinate was hydrolysed to a limited, moderate or extensive degree. The hydrolysates were conjugated with maltodextrin by a Maillard‐type reaction by dry‐heat treatment at 60 °C and 79% relative humidity for 2 or 4 days. Conjugates were characterised by SDS–PAGE and gel permeation chromatography. In comparison with the hydrolysates themselves, the conjugated hydrolysates had improved solubility, particularly around the isoelectric pH of the protein. The emulsifying properties of these conjugates were assessed in oil‐in‐water (o/w) emulsions; on emulsion formation, each conjugate‐stabilised emulsion had lower mean fat globule size than the corresponding hydrolysate‐stabilised emulsion. After storage for 7 days under accelerated shelf life testing conditions, the limited and moderate hydrolysate conjugate–stabilised emulsions had improved storage stability compared with hydrolysate‐stabilised emulsions; however, further research is required to optimise the hydrolysate fraction prior to conjugation for the production of novel low molecular weight emulsifiers.