The role of sodium in the salty taste of permeate.

Many food companies are trying to limit the amount of sodium in their products. Permeate, the liquid remaining after whey or milk is ultrafiltered, has been suggested as a salt substitute. The objective of this study was to determine the sensory and compositional properties of permeates and to determine if elements other than sodium contribute to the salty taste of permeate. Eighteen whey (n=14) and reduced-lactose (n=4) permeates were obtained in duplicate from commercial facilities. Proximate analyses, specific mineral content, and nonprotein nitrogen were determined. Organic acids and nucleotides were extracted followed by HPLC. Aromatic volatiles were evaluated by gas chromatography-mass spectrometry. Descriptive analysis of permeates and model solutions was conducted using a trained sensory panel. Whey permeates were characterized by cooked/milky and brothy flavors, sweet taste, and low salty taste. Permeates with lactose removed were distinctly salty. The organic acids with the highest concentration in permeates were lactic and citric acids. Volatiles included aldehydes, sulfur-containing compounds, and diacetyl. Sensory tests with sodium chloride solutions confirmed that the salty taste of reduced-lactose permeates was not solely due to the sodium present. Permeate models were created with NaCl, KCl, lactic acid, citric acid, hippuric acid, uric acid, orotic acid, and urea; in addition to NaCl, KCl, lactic acid, and orotic acid were contributors to the salty taste.

Relating sensory and chemical properties of sour cream to consumer acceptance.

Sour cream is a widely popular acidified dairy product. Volatile compounds and organic acids and their specific contributions to flavor or acceptance have not been established, nor has a comprehensive study been conducted to characterize drivers of liking for sour cream. The objective of this study was to characterize chemical and sensory properties of sour cream and to determine the drivers of liking for sour cream. Descriptive sensory and instrumental analyses followed by consumer testing were conducted. Flavor and texture attributes of 32 (22 full-fat, 6 reduced-fat, and 4 fat-free) commercial sour creams were evaluated by a trained descriptive sensory panel. Percent solids, percent fat, pH, titratable acidity, and colorimetric measurements were conducted to characterize physical properties of sour creams. Organic acids were evaluated by HPLC and volatile aroma active compounds were evaluated by gas chromatography-mass spectrometry with gas chromatography-olfactometry. Consumer acceptance testing (n=201) was conducted on selected sour creams, followed by external preference mapping. Full-fat sour creams were characterized by the lack of surface gloss and chalky textural attributes, whereas reduced-fat and fat-free samples displayed high intensities of these attributes. Full-fat sour creams were higher in cooked/milky and milk fat flavors than the reduced-fat and fat-free samples. Reduced-fat and fat-free sour creams were characterized by cardboard, acetaldehyde/green, and potato flavors, bitter taste, and astringency. Lactic acid was the prominent organic acid in all sour creams, followed by acetic and citric acids. High aroma-impact volatile compounds in sour creams were 2,3-butanedione, acetic acid, butyric acid, octanal, 2-methyl-3-furanthiol, 1-octene-3-one, and acetaldehyde. Positive drivers of liking for sour cream were milk fat, cooked/milky and sweet aromatic flavors, opacity, color intensity, and adhesiveness. This comprehensive study established sensory and instrumental properties of sour creams and their relationship to consumer acceptance.

Effect of temperature and bleaching agent on bleaching of liquid Cheddar whey.

The use of whey protein as an ingredient in foods and beverages is increasing, and thus demand for colorless and mild-tasting whey protein is rising. Bleaching is commonly applied to fluid colored cheese whey to decrease color, and different temperatures and bleach concentrations are used. The objectives of this study were to compare the effects of hot and cold bleaching, the point of bleaching (before or after fat separation), and bleaching agent on bleaching efficacy and volatile components of liquid colored and uncolored Cheddar whey. First, Cheddar whey was manufactured, pasteurized, fat-separated, and subjected to one of a number of hot (68°C) or cold (4°C) bleaching applications [hydrogen peroxide (HP) 50 to 500 mg/kg; benzoyl peroxide (BP) 25 to 100 mg/kg] followed by measurement of residual norbixin and color by reflectance. Bleaching agent concentrations were then selected for the second trial. Liquid colored Cheddar whey was manufactured in triplicate and pasteurized. Part of the whey was collected (no separation, NSE) and the rest was subjected to fat separation (FSE). The NSE and FSE wheys were then subdivided and bleaching treatments (BP 50 or 100 mg/kg and HP 250 or 500 mg/kg) at 68°C for 30 min or 4°C for 16 h were applied. Control NSE and FSE with no added bleach were also subjected to each time-temperature combination. Volatile compounds from wheys were evaluated by gas chromatography-mass spectrometry, and norbixin (annatto) was extracted and quantified to compare bleaching efficacy. Proximate analysis, including total solids, protein, and fat contents, was also conducted. Liquid whey subjected to hot bleaching at both concentrations of HP or at 100mg/kg BP had greater lipid oxidation products (aldehydes) compared with unbleached wheys, 50mg/kg BP hot-bleached whey, or cold-bleached wheys. No effect was detected between NSE and FSE liquid Cheddar whey on the relative abundance of volatile lipid oxidation products. Wheys bleached with BP had lower norbixin content compared with wheys bleached with HP. Bleaching efficacy of HP was decreased at 4°C compared with 68°C, whereas that of BP was not affected by temperature. These results suggest that fat separation of liquid Cheddar whey has no effect on bleaching efficacy or lipid oxidation and that hot bleaching may result in increased lipid oxidation in fluid whey.

Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey proteins.

Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations in dried whey products. No legal limit exists in the United States for BP use in whey, but international concerns exist. The objectives of this study were to determine the effect of hydrogen peroxide (HP) or BP bleaching on the flavor of 34% WPC (WPC34) and to evaluate residual BA in commercial and experimental WPC bleached with and without BP. Cheddar whey was manufactured in duplicate. Pasteurized fat-separated whey was subjected to hot bleaching with either HP at 500 mg/kg, BP at 50 or 100 mg/kg, or no bleach. Whey was ultrafiltered and spray dried into WPC34. Color [L*(lightness), a* (red-green), and b* (yellow-blue)] measurements and norbixin extractions were conducted to compare bleaching efficacy. Descriptive sensory and instrumental volatile analyses were used to evaluate bleaching effects on flavor. Benzoic acid was extracted from experimental and commercial WPC34 and 80% WPC (WPC80) and quantified by HPLC. The b* value and norbixin concentration of BP-bleached WPC34 were lower than HP-bleached and control WPC34. Hydrogen peroxide-bleached WPC34 displayed higher cardboard flavor and had higher volatile lipid oxidation products than BP-bleached or control WPC34. Benzoyl peroxide-bleached WPC34 had higher BA concentrations than unbleached and HP-bleached WPC34 and BA concentrations were also higher in BP-bleached WPC80 compared with unbleached and HP-bleached WPC80, with smaller differences than those observed in WPC34. Benzoic acid extraction from permeate showed that WPC80 permeate contained more BA than did WPC34 permeate. Benzoyl peroxide is more effective in color removal of whey and results in fewer flavor side effects compared with HP and residual BA is decreased by ultrafiltration and diafiltration.

Effect of liquid retentate storage on flavor of spray-dried whey protein concentrate and isolate.

The objective of this study was to determine the effects of holding time of liquid retentate on flavor of spray-dried whey proteins: Cheddar whey protein isolate (WPI) and Mozzarella 80% whey protein concentrate (WPC80). Liquid WPC80 and WPI retentate were manufactured and stored at 3°C. After 0, 6, 12, 24, and 48h, the product was spray-dried (2kg) and the remaining retentate held until the next time point. The design was replicated twice for each product. Powders were stored at 21°C and evaluated every 4 mo throughout 12 mo of storage. Flavor profiles of rehydrated proteins were documented by descriptive sensory analysis. Volatile components were analyzed with solid phase microextraction coupled with gas chromatography mass spectrometry. Cardboard flavors increased in both spray-dried products with increased retentate storage time and cabbage flavors increased in WPI. Concurrent with sensory results, lipid oxidation products (hexanal, heptanal, octanal) and sulfur degradation products (dimethyl disulfide, dimethyl trisulfide) increased in spray-dried products with increased liquid retentate storage time, whereas diacetyl decreased. Shelf stability was decreased in spray-dried products from longer retentate storage times. For maximum quality and shelf life, liquid retentate should be held for less than 12h before spray drying.

The effect of starter culture and annatto on the flavor and functionality of whey protein concentrate.

The flavor of whey protein can carry over into ingredient applications and negatively influence consumer acceptance. Understanding sources of flavors in whey protein is crucial to minimize flavor. The objective of this study was to evaluate the effect of annatto color and starter culture on the flavor and functionality of whey protein concentrate (WPC). Cheddar cheese whey with and without annatto (15 mL of annatto/454 kg of milk, annatto with 3% wt/vol norbixin content) was manufactured using a mesophilic lactic starter culture or by addition of lactic acid and rennet (rennet set). Pasteurized fat-separated whey was then ultrafiltered and spray dried into WPC. The experiment was replicated 4 times. Flavor of liquid wheys and WPC were evaluated by sensory and instrumental volatile analyses. In addition to flavor evaluations on WPC, color analysis (Hunter Lab and norbixin extraction) and functionality tests (solubility and heat stability) also were performed. Both main effects (annatto, starter) and interactions were investigated. No differences in sensory properties or functionality were observed among WPC. Lipid oxidation compounds were higher in WPC manufactured from whey with starter culture compared with WPC from rennet-set whey. The WPC with annatto had higher concentrations of p-xylene, diacetyl, pentanal, and decanal compared with WPC without annatto. Interactions were observed between starter and annatto for hexanal, suggesting that annatto may have an antioxidant effect when present in whey made with starter culture. Results suggest that annatto has a no effect on whey protein flavor, but that the starter culture has a large influence on the oxidative stability of whey.

Effects of starter culture and storage on the flavor of liquid whey.

UNLABELLED: The primary off flavors in dried whey proteins have been attributed to lipid oxidation products. A deeper understanding of lipid oxidation in fluid whey is crucial to understand how to minimize off flavors in dried whey protein. The objectives of this study were to further elucidate the role of storage and starter cultures as sources of lipid oxidation in whey. Fluid Cheddar, Mozzarella, and rennet-set wheys were manufactured from skim and whole milk. Liquid wheys and milks were evaluated by descriptive sensory and volatile instrumental analysis within 2 h of manufacture and following storage for 3 d at 4 °C. Culture type greatly influenced the oxidative stability of liquid whey, with Cheddar and Mozzarella whey differing not only in sensory profile, but also in volatile compounds. The type of starter culture (Mozzarella compared with Cheddar) had more influence on flavor than the set type (acid compared with culture). Milks had lower relative abundances of volatile free fatty acids than their liquid whey counterparts. Volatile lipid oxidation products in wheys were higher than in their respective milks, but oxidation in both milks and wheys increased with storage time. Wheys from Cheddar starters displayed more oxidation products than wheys from Mozzarella starters. Starter media did not have an effect on the flavor or oxidative stability of liquid whey, however, culture strain influenced lipid oxidation of fluid whey. PRACTICAL APPLICATION: Lipid oxidation products are primary contributors to whey ingredient off-flavors. Flavor plays a critical and limiting role in widespread use of dried whey ingredients, and enhanced understanding of flavor and flavor formation in fluid whey are industrially relevant. Results from this study demonstrate that oxidation occurs in milk prior to cheesemaking but that starter type and starter strain influence also oxidative stability and lipid oxidation off flavors in fluid whey.

Impact of fat reduction on flavor and flavor chemistry of Cheddar cheeses.

A current industry goal is to produce a 75 to 80% fat-reduced Cheddar cheese that is tasty and appealing to consumers. Despite previous studies on reduced-fat cheese, information is critically lacking in understanding the flavor and flavor chemistry of reduced-fat and nonfat Cheddar cheeses and how it differs from its full-fat counterpart. The objective of this study was to document and compare flavor development in cheeses with different fat contents so as to quantitatively characterize how flavor and flavor development in Cheddar cheese are altered with fat reduction. Cheddar cheeses with 50% reduced-fat cheese (RFC) and low-fat cheese containing 6% fat (LFC) along with 2 full-fat cheeses (FFC) were manufactured in duplicate. Cheeses were ripened at 8°C and samples were taken following 2 wk and 3, 6, and 9 mo for sensory and instrumental volatile analyses. A trained sensory panel (n=10 panelists) documented flavor attributes of cheeses. Volatile compounds were extracted by solid-phase microextraction or solvent-assisted flavor evaporation followed by separation and identification using gas chromatography-mass spectrometry and gas chromatography-olfactometry. Selected compounds were quantified using external standard curves. Sensory properties of cheeses were distinct initially but more differences were documented as cheeses aged. By 9 mo, LFC and RFC displayed distinct burnt/rosy flavors that were not present in FFC. Sulfur flavor was also lower in LFC compared with other cheeses. Forty aroma-active compounds were characterized in the cheeses by headspace or solvent extraction followed by gas chromatography-olfactometry. Compounds were largely not distinct between the cheeses at each time point, but concentration differences were evident. Higher concentrations of furanones (furaneol, homofuraneol, sotolon), phenylethanal, 1-octen-3-one, and free fatty acids, and lower concentrations of lactones were present in LFC compared with FFC after 9 mo of ripening. These results confirm that flavor differences documented between full-fat and reduced-fat cheeses are not due solely to differences in matrix and flavor release but also to distinct differences in ripening biochemistry, which leads to an imbalance of many flavor-contributing compounds.

Characterization of alkylmethoxypyrazines contributing to earthy/bell pepper flavor in farmstead cheddar cheese.

Farmstead Cheddar cheeses with natural bandage wrappings have a distinctive flavor profile that is appealing to many consumers. An earthy/bell pepper (EBP) flavor has been previously recognized in some of these cheeses. This study characterized the alkylmethoxypyrazine compounds causing EBP flavor in Farmstead Cheddar cheeses. Eight cheeses were divided into inner, outer, rind, and wrapper sections, and tested for descriptive sensory and instrumental analyses. To assess reproducibility of EBP flavor, cheeses from the same facilities were purchased and tested after 6 and 12 mo. EBP flavor was detected in four out of 8 Farmstead Cheddar cheeses by a trained sensory panel. 2-sec-butyl-3-methoxypyrazine and 2-isopropyl-3-methoxypyrazine were identified as the main sources of EBP flavor in these cheeses by GC/O and GC/MS. In general, those alkylmethoxypyrazines were prevalent in the wrapper (106 to 730 ppb) and rind (39 to 444 ppb) sections of the cheeses. They were either not detected in inner and outer sections of the cheeses or were present at low concentrations. These results suggest that 2-sec-butyl-3-methoxypyrazine and 2-isopropyl-3-methoxypyrazine are formed near the surface of the cheeses and migrate into the cheese during ripening. Threshold values in water and whole milk were 1 and 16 ppt for 2-sec-butyl-3-methoxypyrazine, and 0.4 and 2.3 ppt for 2-isopropyl-3-methoxypyrazine, respectively. Sensory analysis of mild Cheddar cheese model systems confirmed that direct addition of those individual alkylmethoxypyrazines (0.4 to 20 ppb) resulted in EBP flavor.

The effect of refrigerated and frozen storage on butter flavor and texture.

Butter is often stored for extended periods of time; therefore, it is important for manufacturers to know the refrigerated and frozen shelf life. The objectives of this study were to characterize the effect of refrigerated and frozen storage on the sensory and physical characteristics of butter. Fresh butter was obtained on 2 occasions from 2 facilities in 113-g sticks and 4-kg bulk blocks (2 facilities, 2 package forms). Butters were placed into both frozen (-20 degrees C) and refrigerated storage (5 degrees C). Frozen butters were sampled after 0, 6, 12, 15, and 24 mo; refrigerated butters were sampled after 0, 3, 6, 9, 12, 15, and 18 mo. Every 3 mo, oxidative stability index (OSI) and descriptive sensory analysis (texture, flavor, and color) were conducted. Every 6 mo, peroxide value (PV), free fatty acid value (FFV), fatty acid profiling, vane, instrumental color, and oil turbidity were examined. A mixed-model ANOVA was conducted to characterize the effects of storage time, temperature, and package type. Storage time, temperature, and package type affected butter flavor, OSI, PV, and FFV. Refrigerated butter quarters exhibited refrigerator/stale off-flavors concurrent with increased levels of oxidation (lower oxidative stability and higher PV and FFV) within 6 mo of refrigerated storage, and similar trends were observed for refrigerated bulk butter after 9 mo. Off-flavors were not evident in frozen butters until 12 or 18 mo for quarters and bulk butters, respectively. Off-flavors in frozen butters were not correlated with instrumental oxidation measurements. Because butter is such a desirable fat source in terms of flavor and textural properties, it is important that manufacturers understand how long their product can be stored before negative attributes develop.