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.     

Oil‐in‐Water Emulsion Exhibits Bitterness‐Suppressing Effects in a Sensory Threshold Study

Little is known about how emulsion characteristics affect saltiness/bitterness perception. Sensory detection and recognition thresholds of NaCl, caffeine, and KCl in aqueous solution compared with oil‐in‐water emulsion systems were evaluated. For emulsions, NaCl, KCl, or caffeine were dissolved in water + emulsifier and mixed with canola oil (20% by weight). Two emulsions were prepared: emulsion 1 (viscosity = 257 cP) and emulsion 2 (viscosity = 59 cP). The forced‐choice ascending concentration series method of limits (ASTM E‐679‐04) was used to determine detection and/or recognition thresholds at 25 °C. Group best estimate threshold (GBET) geometric means were expressed as g/100 mL. Comparing NaCl with KCl, there were no significant differences in detection GBET values for all systems (0.0197 ‐ 0.0354). For saltiness recognition thresholds, KCl GBET values were higher compared with NaCl GBET (0.0822 ‐ 0.1070 compared with 0.0471 ‐ 0.0501). For NaCl and KCl, emulsion 1 and/or emulsion 2 did not significantly affect the saltiness recognition threshold compared with that of the aqueous solution. However, the bitterness recognition thresholds of caffeine and KCl in solution were significantly lower than in the emulsions (0.0242 ‐ 0.0586 compared with 0.0754 ‐ 0.1025). Gender generally had a marginal effect on threshold values. This study showed that, compared with the aqueous solutions, emulsions did not significantly affect the saltiness recognition threshold of NaCl and KCl, but exhibited bitterness‐suppressing effects on KCl and/or caffeine.     

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.     

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.     

AGAR AND GELATIN GEL FLAVOR RELEASE

The taste suppression and rupture properties of 0.8-2.0% w/w agar gel and 3.0-6.5% w/w gelatin gel were studied by sensory evaluation and objective measurement. Flavor compound concentrations were determined to equalize the intensity of aspartame sweetness (0.02% w/w for both agar and gelatin gels), sodium chloride saltiness (0.9% w/w for agar gel and 0.2% w/w for gelatin gel), and caffeine bitterness (0.08% w/w for agar gel and 0.07% w/w for gelatin gel) in 1% w/w agar gel and 4.5% w/w gelatin gel. The coefficient of taste intensity = (concentration of flavor compound in the aqueous solution of equiintense taste in gel)/(concentration of flavor compound in gel) was used to compare the difference in gel taste suppression. The coefficient of saltiness intensity of 3.0% w/w gelatin gel exceeded 1.0, and those of other gels were below 1.0. The suppressed variation of the coefficient of saltiness intensity in agar gel was significantly (P<0.01) smaller than that of bitterness depending on agar concentration. No significant differences (P>0.05) in taste suppression between gelatin gels containing the 3 flavor compounds due to changes in gelatin concentration were observed. Rupture energy, which is related to mastication and is a common scale for agar and gelatin gels, was used to evaluate changes in suppression of the coefficient of taste intensities of the 2 gels. The coefficient of bitterness intensity of agar gels was more significantly (P<0.01) suppressed than sweetness and saltiness intensities of gelatin gels. The coefficient of sweetness intensity of gelatin gels was suppressed significantly less than bitterness (P < 0.05) of gelatin gels and sweetness (P < 0.05) and bitterness (P < 0.01) of agar gels.     

KCI, CaCI2, Na+ Binding, and Salt Taste of Gum Systems

Aqueous nonionic (0.3% w/v) and ionic (0.1% and 0.3% w/v) gum systems containing NaCl, or equal weights of NaCl plus KCl, or NaCl plus CaCl, were examined. At equivalent molar concentrations of added ions, ²³Na NMR transverse relaxation rates (R₂, set^?1) showed an increase in average Na⁺ mobility with the addition of K⁺ or Ca²⁺ to ionic gum systems. Correspondingly, salt taste increased with addition of KCl as determined by Decision Boundary modeling of subject identification data. Viscosity did not affect saltiness. Na⁺ was free to induce salt taste when K⁺ was bound to the gum. Enhancement of salt taste by KCl is due, in part, to competitive binding of Na⁺ and K⁺ in a system.     

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.     

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.     

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.     

Cross‐linking of bovine and caprine caseins by microbial transglutaminase and their use as microencapsulating agents for n‐3 fatty acids

Bovine and caprine caseins were cross‐linked with microbial transglutaminase (mTG). The mTG‐cross‐linked bovine or caprine casein dispersion, mixed with 14.5% maltodextrin (DE = 40), was used to prepare emulsions with 10.5% algae oil. Oxidative stability of emulsions was evaluated by peroxide values (PVs) and anisidine values. Adding liposoluble rosemary extract rich in carnosic acid and δ‐tocopherol lowered the formation of hydroperoxides and their subsequent decomposition products in emulsions. Emulsions stabilised with liposoluble rosemary extract rich in carnosic acid and δ‐tocopherol were spray‐dried at 180/95 °C. Algae oil microencapsulated with mTG‐cross‐linked bovine casein reduced PV by ≈ 34%, while the algae oil microencapsulated with mTG‐cross‐linked caprine casein with low levels of α_s1‐casein reduced PV by ≈ 42% at 4 weeks of storage at 30 °C. The investigation suggests that liposoluble rosemary extract rich in carnosic acid and δ‐tocopherol effectively protected algae oil during the coating process with mTG‐cross‐linked bovine and caprine caseins. The above results clearly indicated that the choice of milk caseins (bovine vs. caprine) cross‐linked with mTG impacts the oxidative stability of spray‐dried algae oil emulsions (microcapsules) enriched with n‐3 fatty acids.     

MASKING OF THE BITTER TASTE OF SALT SUBSTITUTES WITH LACTOSE IN FOOD EMULSIONS

The forced-choice triangle test was used in the sensory evaluation of two emulsions containing salt mixtures similar to Morton Lite Salt or Mineral Salt against the same emulsions containing NaCl with an equal level of saltiness. 1%–2% wt/wt of lactose either in combination with sucrose or glucose and galactose produced a flavor which was not distinguished from that of 1.00% of NaCl. Sucrose alone was not able to mask the bitter taste of the mixtures in mayonnaise, nor were the other sugars in combination with 0.3% of lactose and 3.0% of vinegar in a simple emulsion. Doubling the vinegar concentration produced a complicated masking behavior with increasing concentration of lactose.     

Two‐stage processing of salmon backbones to obtain high‐quality oil and proteins

Traditional processing technologies for fish by‐products containing significant amounts of oils usually either give high amounts of oil or maximised solubilisation of proteins. Due to lower yields and insufficient quality, the proteins or the oil is considered as secondary products. The proposed concept combines a gentle thermal separation of oil followed by enzymatic hydrolysis of the remaining protein‐rich fraction. The first stage, thermal treatment (40 °C) of fresh salmon backbones, separated up to 85% of the oil from the raw material and gave high‐quality oil (PV = 0.2 ± 0.0 meq kg^?1, 0.16 ± 0.05% free fatty acids). Separation of a significant part of the oil gave reduced mass flow into the enzymatic stage, which then requires less enzymes and reduced energy consumption. Among the tested enzymes: Trypsin, Corolase PP and Mixture of Papain and Bromelain gave the highest yield of fish protein hydrolysates (FPH), while use of Protamex and Corolase PP resulted in FPH with the best sensory properties leading to the lowest bitterness.     

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.     

RHEOLOGICAL STUDY OF O/W EMULSIONS CONTAINING DRIED WHOLE EGG AND LOCUST BEAN GUM

The influence of sucrose addition and type of salt (NaCl; Morton Lite salt: 50% NaCl and 50% KCl, and Mineral salt: 65% NaCl, 25% KCl and 10% MgSO₄) on the rheological properties of O/W emulsions containing locust bean gum was analyzed. Flow curves over the range 0.1 to 100 s⁻¹ and transient flow curves at 0.2 s⁻¹, at 20 and 30C were obtained for 12 different emulsions, containing 30% (w/w) of sunflower oil. The K and n power law parameters and the hysteresis loop area (HL) were evaluated from the flow curve. So were the Hahn parameters from time-dependent stress decay fitting. Rheological behaviour of emulsions was affected by the type of salt and the presence of sucrose. Changes in solvent properties of the continuous phase in the emulsions on the macromolecules present could be responsible for the different behaviour. The ageing effect on flow behaviour parameters and on the hysteresis loop area was also studied. Evolution of rheological parameters during emulsion storage suggests that increase of ionic strength and polar solutes concentration decrease the stabilizing properties of locust bean gum.     

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.     

The efficacy of bitter blockers on health-relevant bitterants

Current strategies for decreasing the bitterness of conventional foods often involve the addition of sucrose and sodium chloride. However this has limited application with functional foods, as they are health promoting, and other approaches are required. This study assesses the efficacy of high and low concentrations of five bitter inhibiting compounds [β-cyclodextrin (β-CYCLO), homoeriodictyol sodium salt (HED), zinc sulphate monohydrate (ZnSO₄), magnesium sulphate (MgSO₄), carboxymethylcellulose sodium salt (CMC)] on the perceived bitterness of high and low concentrations of (+)-catechin and caffeine – two ingredients used in functional food formulations. Intensity ratings (bitterness, sourness, saltiness, sweetness, savoriness, astringency, ‘other’) of bitterant-bitter blocker binary solutions were collected from a panel of twelve, in duplicate, using a 15 cm line scale. Overall, β-CYCLO and HED were the most effective blockers at decreasing the bitterness of (+)-catechin, while the bitterness of caffeine was reduced most effectively by HED. Results also demonstrate that the bitter reducing capacity of these blockers is bitterant dependent. In general, these bitter blockers elicit minimum side tastes and sensations, although astringency and viscosity intensities are increased under some conditions. We conclude that some bitter blockers show considerable potential for decreasing the bitterness of phenols and caffeine in functional food formulations.     

Effects of Varying Levels of Chloride Salts on Clostridium Botulinum Toxin Production in Turkey Frankfurters

Inhibitory effects of sodium chloride (NaCl), potassium chloride (KCl), and magnesium chloride (MgCl₂) on C. botulinum inoculated turkey frankfurter emulsions were determined. Ionic strengths (I.S.) of 0.42, 0.55, and 0.68 were compared (equivalent to 2.5%, 3.25%, and 4.0% NaCl). Sodium nitrite levels were constant at 150 ppm. Inoculated emulsions (10³ spores/g) were incubated and maintained at 27°C. In-creasing NaCl from I.S. 0.42 to 0.68 delayed toxin production from 4 days to at least 40 days. KCl was almost as effective as NaCl at I.S. 0.42, but inferior at higher levels. MgCl₂ did not demonstrate any inhibitory effect. Fifty percent substitution of 2.5% NaCl with KCl or MgCl₂ generally reduced time for toxin production to occur.     

Stability and release properties of double emulsions for food applications

Water-in-oil-in-water (W₁/O/W₂) double emulsions (DEs) containing gelatin and sodium chloride (NaCl) in the inner aqueous phase were developed for controlled release applications. Emulsions were prepared with water and canola oil, as well as with polyglycerol polyricinoleate and polysorbate 80 as emulsifiers for the primary water-in-oil (W₁/O) emulsion and secondary W₁/O/W₂ emulsions, respectively. All DEs containing both NaCl and gelatin were stable against sedimentation for the month-long study whereas control emulsions (with either no NaCl or gelatin) showed visual phase separation. The average oil globule size in freshly-prepared DEs grew from ∼45 to 70 μm with an increase in salt load from 2 to 8% (w/w), and changed little after 1 month. Besides its role in stabilization, NaCl was also used as a marker to evaluate DE release behaviour. The salt diffusion coefficient obtained using Fujita’s model rose from 4.7 to 6.0 × 10⁻¹¹ cm²/s with increasing NaCl concentration in the DEs from 2 to 8% (w/w). All stable DEs showed a high salt retention in the inner aqueous phase (>94%) after 1 month of storage at 4 °C. These results demonstrated the synergistic action of a gelling agent and electrolyte in stabilizing and modulating the release behaviour of NaCl from W₁/O/W₂ DEs.