EFFECT OF HOMOGENIZATION AND FAT CONTENT ON ORAL PERCEPTION OF LOW AND HIGH VISCOSITY MODEL CREAMS

Assessed under low-intensity red illumination, homogenized and thickened higher fat milk samples evoked higher sensory ratings of creaminess than did the unhomogenized or lower-fat milks that had not been thickened to the viscosity of double cream. Furthermore, perceptual ratings of fat content showed the same dependency on homogenization, higher fat and thickness and were entirely accounted for by the creaminess ratings. This indicates that assessors recognize the type of milk or cream most similar to a rated standard and infer its fat content on the basis of tactile patterns produced in the mouth by forces at the surface of small and even-sized dairy fat globules when bulk forces are produced by sufficient viscosity.     

COMPARISON OF THE SENSORY PROPERTIES OF ULTRA-HIGH-TEMPERATURE (UHT) MILK FROM DIFFERENT COUNTRIES

Shelf-stable milk, also known as ultra-high-temperature (UHT) milk is the most common form of milk in many parts of the world. This study compared the differences in flavor and texture of 37 commercially available UHT and sterilized milk samples including whole, 2% reduced-fat and low-fat milk obtained from markets in seven countries: France ( n =  2), Italy ( n =  11), Japan ( n =  1), Korea ( n =  2), Peru ( n =  3), Thailand ( n =  13) and the U.S.A. ( n =  5). Five highly trained panelists used flavor and texture profiling to describe the sensory properties of each milk sample. Data were analyzed by principal component analysis and hierarchical cluster analysis. Higher levels of processed, chalky, brown and cooked flavor notes generally corresponded to lower levels of fresh dairy flavor characteristics. In general, samples did not vary consistently within a country. Fat content did not correlate with dairy fat flavor or with viscosity. This research suggests that companies' manufacturing processes for UHT milk may have more impact than country or fat content in determining sensory properties of UHT milk.

PRACTICAL APPLICATIONS

Sensory properties of UHT milk from different countries developed in this study could be used by the dairy industry to understand the similarities and differences of UHT milk characteristics from different regions and to modify UHT milk characteristics to meet consumers' criteria or expectation. The study suggests that manufacturers who want to improve quality of UHT milk by modify flavor and texture properties should focus on improvements to the manufacturing processes.     

RELEASE OF ARTIFICIAL CHERRY FLAVOR FROM ICE CREAMS VARYING IN FAT AND FAT REPLACERS

The effect of fat and fat replacers (FR) on the flavor release from cherry ice cream was investigated. Protein based FR, Simplesse ("S") and carbohydrate based FR, Litesse ("L") either partially or completely substituted milk fat in ice cream. Overall and temporal flavor profiles of ice cream during eating were obtained using chemical and sensory analyses. The performance of FR depended on the level of fat it was substituting and the amount of fat present in the ice cream. In the reduced fat ice cream group, both FRs failed to mimic the characteristics of 6% fat ice cream, mainly because of the low retention of cherry flavor. In the full fat ice cream group, the sensory properties of ice cream containing "L" were closer to the full-fat (12%) ice cream than those with "S". The critical flavor volatile compounds that strongly impact the sensory flavor attributes were identified.     

Exploiting the Functionality of Lactic Acid Bacteria in Ice Cream

In this study, the fermented milk of three ropy (NCFB 2483, CRNZ 737, and LB18) and one non-ropy strains (LH30) of lactic acid bacteria were each added to aged ice cream mixes prepared with and without commercial stabilizers. Ice cream mixes with NCFB 2483 and LB18 (without stabilizers) achieved significantly higher overrun than the sample with non-ropy culture (with stabilizers). Evaluation of meltdown resistance and firmness of the ice cream indicated that samples with NCFB 2483 and LB18 ferment (without stabilizers) were comparable to ice cream with non-ropy culture (with stabilizers). Results of the particle size D[4,3] of the ice cream melt showed that the main mechanism for fat destabilization was not partial coalescence but fat aggregation due to the interactions of milk proteins and/or polysaccharides at the interface of fat globules. There was generally no significant difference in partial coalescence of the fat globules in all samples except LB18 (with stabilizers) where partial coalescence appeared to be significantly lower. The viscoelastic properties of ropy milk appeared to influence the functional properties of ice cream.     

Selenium content of milk and milk products of Turkey. II

Selenium content of 1028 milk and milk products of Turkey are presented in this study. The selenium content of human milk (colostrum, transitional, and mature milk), various kinds of milk [cow, sheep, goat, buffalo, paper boxes (3%, 1.5%, 0.012% fat), bottled milk, condensed milk (10% fat), mineral added milk (1.6%), and banana, strawberry, and chocolate milk] and milk products (kefir, yogurt, Ayran, various cheese, coffee cream, ice cream, butter, margarine, milk powder, and fruit yogurt) in Turkey were determined by a spectrofluorometric method. The selenium levels of cow milks collected from 57 cities in Turkey were also determined. Selenium levels in cow milk varied with geographical location in Turkey and were found to be lowest for Van and highest for Aksaray. The results [milk (cow, sheep, goat, buffalo and human) and milks products] were compared with literature data from different countries.     

Revisiting sugar-fat mixtures: sweetness and creaminess vary with phenotypic markers of oral sensation

Genetic variation in oral sensation presumably influences ingestive behaviors through sensations arising from foods and beverages. Here, we investigated the influence of taste phenotype [6-n-propylthiouracil (PROP) bitterness, fungiform papillae (FP) density] on sweet and creamy sensations from sugar/fat mixtures. Seventy-nine subjects (43 males) reported the sweetness and creaminess of water or milk (skim, whole, heavy cream) varying in sucrose (0-20% w/v) on the general Labeled Magnitude Scale. Sweetness grew with sucrose concentration and when shifting from water to milk mixtures--the growth was greatest for those tasting PROP as most bitter. At higher sucrose levels, increasing fat blunted the PROP-sweet relationship, whereas at lower levels, the relationship was effectively eliminated. Perceived sweetness of the mixture exceeded that predicted from the sum of components at low sucrose concentrations (especially for those tasting PROP most bitter) but fell below predicted at high concentrations, irrespective of fat level. Creaminess increased greatly with fat level and somewhat with sucrose. Those tasting PROP most bitter perceived greater creaminess in the heavy cream across all sucrose levels. Perceived creaminess was somewhat lower than predicted, irrespective of PROP bitterness. The FP density generally showed similar effects as PROP on sweetness and creaminess, (but to a lesser degree) and revealed potential taste-somatosensory interactions in weakly sweet stimuli. These data support that taste phenotype affects the nature of enhancement or suppression of sweetness and creaminess in liquid fat/sugar mixtures. Taste phenotype effects on sweetness and creaminess likely involve differential taste, retronasal olfactory, and somatosensory contributions to these perceptual experiences.     

INFLUENCE OF FOOD MATRIX STRUCTURE AND ORAL BREAKDOWN DURING MASTICATION ON TEMPORAL PERCEPTION OF FLAVOR

Perception of flavor intensity from a series of model foods was recorded during normal mastication by 8 subjects. Samples varied in gelatin concentration (5–25%) and in the sweetener added (sucrose or aspartame) and represented a range of physical and mechanical properties. All contained the same level of a commercial flavor (banana). Mastication patterns were recorded using electromyography simultaneously with sensory assessment. Increasing the mechanical strength and melting point of the samples resulted in longer chewing times and lower intensity and more prolonged flavor perception. The temporal pattern of flavor perception was closely linked with mastication patterns for each subject but exhibited large individual differences. Flavor perception was influenced by the habitual oral breakdown patterns for individuals.     

Insulin potentiating factor and chromium content of selected foods and spices.

An unidentified factor that potentiates the action of insulin in glucose metabolism was investigated in selected foods and spices. Chromium content of these foods and spices was also determined. Foods and spices were extracted with 0.1N NH4OH (1:20, w/v) and the supernatants assayed for insulin potentiation activity in the rat epididymal fat cell assay. Among the selected foods, tuna fish, peanut butter, and vanilla ice cream had some insulin potentiating activity. Among the spices, apple pie spice, cinnamon, cloves, bay leaves, and turmeric potentiated insulin activity more than three-fold. Chromium concentration of foods ranged from 1 to 145 ng/g, and spices ranged from 4 to 1818 ng/g. Insulin potentiating activity of foods and spices did not correlate with total chromium. Spices are generally used for flavor and taste in food preparations, but cinnamon, cloves, bay leaves, and turmeric may have an additional role in glucose metabolism.     

THE PSYCHOPHYSICAL RELATIONSHIP BETWEEN COLOR AND SALT CONCENTRATIONS IN CHICKEN FLAVORED BROTHS

Taste panelists evaluated the effect of color on salt perception in chicken flavored samples using magnitude estimation. Samples were colored to simulate commercial chicken broth. Five color intensities were added to 5 NaCl concentrations ranging from 0.34 to 0.66% (w/v). Color had no influence on salt perception. Panelists were able to perceive color differences among samples (P <0.001) and these were correlated with the objective color function cot⁻¹ (a/b) calculated from the L,a,b values obtained from the Gardner XL-23. Overall flavor preference was evaluated by a taste panel using the technique of magnitude estimation. NaCl concentrations ranged from 0.52 to 0.80% (w/v). Overall flavor preference was unaffected by color. A reduction in NaCl concentration from 0.80% (w/v) to 0.52% (a 35% reduction) did not alter flavor preference. A 50 member consumer panel using a paired comparison test found no difference in flavor preference between an uncolored sample containing 0.80% (w/v) NaCl and a colored sample containing 0.72% (w/v) NaCl.     

EFFICIENCY OF A CYCLIC DESIGN AND A MULTIDIMENSIONAL SCALING SENSORY ANALYSIS TECHNIQUE IN THE STUDY OF SALT TASTE

Multidimensional scaling (MDS) procedures produce maps of stimulus points, the dimensions of which may be sensory and/or physicochemical attributes. Our objective was to test the efficiencies of a cyclic design and a MDS method in the study of saltiness perception. Two levels of NaCl (0.1% and 0.2%, w/v) were added to two nonionic and two ionic gum solutions prepared to two concentrations. Subjects scaled dissimilarities between pairs of solutions and rated each sample for flavor attributes. Solution pairs were selected using cyclic designs. Repeated measures ANOVA determined that added NaCl was the only significant factor affecting saltiness perception. In contrast, from KYST-2A MDS maps, we concluded that saltiness perception was influenced by gum property, gum concentration, presence of calcium and potassium, and related to binding of the sodium ion (Na⁺) as determined by ²³Na nuclear magnetic resonance (NMR) spectroscopy. The MDS cyclic design successfully reduced the number of samples and subjects when using experienced subjects.     

SENSORY PROPERTIES AND CONSUMER PERCEPTION OF 'HOME-MADE'AND COMMERCIAL DAIRY ICE CREAM

Sensory properties and consumer perception of 2 'home-made'and 4 commercial dairy ice creams were examined. Conventional profiling by a trained panel found that most samples differed significantly in all attributes, but distinction of 'home-made'from commercial products was limited to few attributes. Principal component analysis separated the 'home-made'products from the commercial ones mainly on the basis of differences in appearance, aroma, creamy flavors and textural attributes. A consumer group (n=105) recorded preconception of 'home-made'ice cream acceptance, then received the product samples, in unlabeled condition, for assessment of degree of liking (DOL) and for identification as 'home-made'or commercial. Internal preference mapping of the DOL ratings showed that consumers were more closely grouped around samples which had higher intensities of certain attributes. Higher 'denseness', 'vanilla'aroma and 'buttery'flavor, were associated with more liking for commercial products. The 'home-made'high fat sample, although liked, tended to be grouped with commercial products. More marked textural attributes of 'ice crystals'and 'breakage'aided identification of the low-fat 'home-made'formulation, which was less liked overall. Overall, differences between the 'home-made'and commercial samples were small but consumer perception of the term 'home-made'was viewed favorably for dairy ice cream.     

Use of isolated kefir starter cultures in kefir production

Kefir is a beverage produced by lactic-alcoholic fermentation of milk using kefir grain. For the first time in Iran, the microbial flora of kefir grain was isolated and identified (Motaghi et al. 1997). In this paper various ratios of starter cultures of kefir grains were investigated. Various ratios of lactic acid bacteria, yeasts and acetic acid bacteria were tested and the quality (colour, smell, flavour, acidity, effervescence and viscosity) of the product was assessed. At constant incubation time and temperature (24 h, 25 °C using homogenised milk with 2.5% fat), samples with various ratios of starter culture (3–5% w/v) were examined and analysed for protein, fat, sugar, alcohol, carbon dioxide, acidity, density, and riboflavin content. Samples produced with 3% (v/v) bacterial mixed culture and 2% (v/v) yeast (K3 procedure) culture were considered as best with respect to quality and organoleptic quality. The comparison of the results with the organoleptic tests of previous studies showed that the kefir produced with kefir grain is more desirable as compared with kefir produced with starter cultures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Enhancement of cheese flavors with microbial esterases

The characteristic flavor of hard Italian cheeses is associated with the presence of fatty acids, particularly butyric acid, liberated from milk fat during the ripening process. To ensure proper development and control of flavor, animal pregastric esterases or lipases are routinely added to the milk before coagulation of the curd. Such esterases are also used to generate flavor in enzyme modified cheese and other dairy products. Esterases from microbial sources have been investigated as agents to enhance flavor in cheese. We have found that an esterase from Mucor miehei exhibits the type of lipolytic activity needed for this application. Romano and fontina cheeses of excellent quality have been prepared by the use of this esterase. It has also been used successfully in the preparation of enzyme modified cheese, and, in turn, processed American cheese.     

Antioxidant Effect of Tocopherols on Autoxidation of Milk Fat

The lipid isolated from the fat globule membrane of milk was quickly autoxidized. The development of off-flavor like fishy flavor and brown color took place simultaneously. The browning material seemed to decompose fat peroxide. The addition of α-, γ- and δ-tocopherol into the membrane lipid inhibited the formation of fat peroxide and off-flavor and decreased the browning degree. The addition of the membrane lipid prolonged the induction period of the oxidation of the milk fat obtained by churning. The antioxidant activity of aα-, γ- and δ-tocopherols added into the churned milk fat containing 1% of the membrane lipid was higher than that of the tocopherols added into the churned milk fat containing no membrane lipid.     

FREE-CHOICE PROFILING OF MILKS AND OTHER PRODUCTS PREPARED WITH MILKS OF DIFFERENT FAT CONTENTS

Free-choice profiling was used to develop a sensory profile of milks of different fat content and a range of food products prepared from them. The products were cornflakes, flavored milk, instant coffee, oat cereal, savory sauce, tea, and whipped dessert. The aim of the work was to investigate whether or not sensory differences brought about by using milk with a different fat content are noticeable in the context of use, and, if so how the differences can best be described. The milks of different fat content, the flavored milk and the cornflakes, savory sauce, and tea to which milk was added were significantly different from each other but the instant coffee, oat cereal, and whipped desserts were not. The differences found between the samples of different fat content were most often described with mouthfeel terms pertaining to viscosity, i.e., “thin/watery,”“buttery/fatty/ greasy/oily,”“coating/clinging,” and “creamy/rich.”     

Milk Fat Content and DGAT1 Genotype Determine Lipid Composition of the Milk Fat Globule Membrane

During secretion of milk fat globules, triacylglycerol (TAG) droplets are enveloped by a phospholipid (PL) trilayer. Globule size has been found to be related to polar lipid composition and fat content, and milk fat content and fatty acid composition have been associated with the diacylglycerol acyltransferase 1 (DGAT1) K232A polymorphism; however, the association between the DGAT1 polymorphism and fat globule size and polar lipid composition has not been studied. The ratio between polar and neutral lipids as well as the composition of the polar lipids in milk has industrial as well as nutritional and health implications. Understanding phenotypic and genotypic factors influencing these parameters could contribute to improving milk lipid composition for dairy products. The focus of the present study was to determine the effect of both fat content and DGAT1 polymorphism on PL/TAG ratio, as a marker for milk fat globule size, and detailed PL composition. Milk samples were selected from 200 cows such that there were equal numbers of samples for the different fat contents as well as per DGAT1 genotype. Samples were analyzed for neutral and polar lipid concentration and composition. PL/TAG ratio was significantly associated with both fat content and DGAT1 genotype. Phosphatidylinositol and phosphatidylserine concentrations were associated with fat content*DGAT1 genotype with a stronger association for the AA than the KK genotype. Sphingomyelin concentration tended to interact with fat content*DGAT1 genotype. Phosphatidylethanolamine (PE) concentration showed a biphasic response to fat content, suggesting that multiple biological processes influence its concentration. These results provide a new direction for controlling polar lipid concentration and composition in milk through selective breeding of cows.     

FUZZY MULTIATTRIBUTE DECISION MAKING APPROACH FOR DEVELOPMENT AND COMPARISON OF SOY FORTIFIED PANEER

Soyfortified paneer (SFP) samples prepared from blends containing different proportions of buffalo milk of varying fat content and soy milk (7.5 °B) were evaluated organoleptically for assessing the quality attributes like body and texture, flavor and taste, color and appearance and the overall acceptability. Sensory data were analyzed using fuzzy logic approach, which addresses the problem of data classification in a unified qualitative and quantitative manner. Results of the study indicated that the fuzzy multiattribute decision making approach provide an adequate and reliable system for product formulation and comparison, based on sensory data. The developed fuzzy mathematical model performed remarkably well in the evaluation and ranking of various SFP samples. The SFP sample made from blend of buffalo milk (4.5% fat) and soy milk (7.5 °B) in the proportion of 90:10 was found to be the most acceptable one for different classes of consumers irrespective of their preferences for a particular sensory quality attribute.