Impact of model fat emulsions on sensory perception using repeated spoon to spoon ingestion.

Eating is a dynamic behaviour, in which food interacts with the mechanical and physiological environment of the mouth. This dynamic interaction changes the oral surfaces leaving particles of food and building up a film on the oral surfaces, which may impact on the temporal perception during the eating experience. The effect of repeated spoon to spoon ingestion of oil in water emulsion products (2%-50% w/w oil) was evaluated using descriptive in-mouth and after swallowing sensory attributes. Descriptive sensory analysis indicated that fatty mouthfeel and afterfeel perception (measured post swallowing) increased with the number of spoonfuls for emulsions containing 50% fat. This effect is likely due to the build-up of oil droplet layers deposited on the mouth surfaces. There was an enhancement of fatty afterfeel intensity for 50% fat emulsions containing the more lipophilic aroma ethylhexanoate compared to ethyl butanoate, indicating a cross-modal interaction. No increase in these attributes from spoon to spoon was observed for the low oil emulsions; since most of the oil in the emulsion was swallowed and very little oil was likely to be left in the mouth. Sweetness perception increased as fat level increased in the emulsion due to an increase in the effective concentration of sugar in the aqueous phase. However, the sweetness perceived did not change from spoon to spoon, suggesting that any oil-droplets deposited on the oral surfaces did not form a complete barrier, restricting access of the sucrose to the taste buds. This study highlights the importance of measuring the dynamic nature of eating and demonstrated change in sensory perception occurring with repeated ingestion of model emulsions, which was likely due to a change in mouth environment.

Effects of different forms of hazelnuts on blood lipids and α-tocopherol concentrations in mildly hypercholesterolemic individuals.

BACKGROUND/OBJECTIVES: Diets high in nuts reduce cholesterol, probably due to their favorable lipid profile and other bioactive substances. However, the physical form of the nut may be important as the cell wall of intact nuts may limit the hypocholesterolemic effect of nuts by reducing lipid bioavailability. Therefore, we investigated the effects on blood lipids of incorporating three different forms of hazelnuts (ground, sliced and whole) into the usual diet. SUBJECTS/METHODS: In a randomized crossover study with three phases, 48 mildly hypercholesterolemic participants were asked to consume 30 g of ground, sliced or whole hazelnuts for 4 weeks. Body weight, plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triacylglycerol (TAG), apolipoprotein (apo) A1, apo B100 and α-tocopherol were measured at baseline and at the end of each dietary phase. RESULTS: There were no significant differences in any outcome variable between the different forms of nuts (all P ≥ 0.159). However, compared with baseline, mean values at the end of each hazelnut intervention were significantly higher for HDL-C (P = 0.023) and α-tocopherol (P = 0.005), and significantly lower for TC (P < 0.001), LDL-C (P < 0.001), TC:HDL-C ratio (P <0 .001), apo B100 (P = 0.002) and apo B100:apo A1 ratio (P < 0.001), with no significant difference in body weight (P = 0.813). CONCLUSIONS: The ingestion of three different forms of hazelnuts equally improved the lipoprotein profile and α-tocopherol concentrations in mildly hypercholesterolemic individuals. Hazelnuts can therefore be incorporated into the usual diet as a means of reducing cardiovascular disease risk.

Application of mid-infrared spectroscopy to the prediction of maturity and sensory texture attributes of cheddar cheese.

The objective of this study was to determine the potential of mid-infrared spectroscopy in conjunction with partial least squares (PLS) regression to predict various quality parameters in cheddar cheese. Cheddar cheeses (n= 24) were manufactured and stored at 8 degrees C for 12 mo. Mid-infrared spectra (640 to 4000/cm) were recorded after 4, 6, 9, and 12 mo storage. At 4, 6, and 9 mo, the water-soluble nitrogen (WSN) content of the samples was determined and the samples were also evaluated for 11 sensory texture attributes using descriptive sensory analysis. The mid-infrared spectra were subjected to a number of pretreatments, and predictive models were developed for all parameters. Age was predicted using scatter-corrected, 1st derivative spectra with a root mean square error of cross-validation (RMSECV) of 1 mo, while WSN was predicted using 1st derivative spectra (RMSECV = 2.6%). The sensory texture attributes most successfully predicted were rubbery, crumbly, chewy, and massforming. These attributes were modeled using 2nd derivative spectra and had corresponding RMSECV values in the range of 2.5 to 4.2 on a scale of 0 to 100. It was concluded that mid-infrared spectroscopy has the potential to predict age, WSN, and several sensory texture attributes of cheddar cheese.

Evaluating mid-infrared spectroscopy as a new technique for predicting sensory texture attributes of processed cheese.

The objective of this study was to investigate the potential application of mid-infrared spectroscopy for determination of selected sensory attributes in a range of experimentally manufactured processed cheese samples. This study also evaluates mid-infrared spectroscopy against other recently proposed techniques for predicting sensory texture attributes. Processed cheeses (n = 32) of varying compositions were manufactured on a pilot scale. After 2 and 4 wk of storage at 4 degrees C, mid-infrared spectra (640 to 4,000 cm(-1)) were recorded and samples were scored on a scale of 0 to 100 for 9 attributes using descriptive sensory analysis. Models were developed by partial least squares regression using raw and pretreated spectra. The mouth-coating and mass-forming models were improved by using a reduced spectral range (930 to 1,767 cm(-1)). The remaining attributes were most successfully modeled using a combined range (930 to 1,767 cm(-1) and 2,839 to 4,000 cm(-1)). The root mean square errors of cross-validation for the models were 7.4 (firmness; range 65.3), 4.6 (rubbery; range 41.7), 7.1 (creamy; range 60.9), 5.1 (chewy; range 43.3), 5.2 (mouth-coating; range 37.4), 5.3 (fragmentable; range 51.0), 7.4 (melting; range 69.3), and 3.1 (mass-forming; range 23.6). These models had a good practical utility. Model accuracy ranged from approximate quantitative predictions to excellent predictions (range error ratio = 9.6). In general, the models compared favorably with previously reported instrumental texture models and near-infrared models, although the creamy, chewy, and melting models were slightly weaker than the previously reported near-infrared models. We concluded that mid-infrared spectroscopy could be successfully used for the nondestructive and objective assessment of processed cheese sensory quality.

Production of ingredient-type cheddar cheese with accelerated flavor development by addition of enzyme-modified cheese powder.

Fast-ripened Cheddar cheeses for ingredient purposes were produced by addition of a dried enzyme-modified cheese (EMC; 0.25 and 1 g/100 g of milled curd) at the salting stage during a standard Cheddar cheese-making procedure. Populations of starter and nonstarter lactic acid bacteria (NSLAB), levels of proteolysis and lipolysis, volatile analysis, and flavor development (by quantitative descriptive sensory analysis) were monitored over a 6-mo ripening period. Levels of free AA and free fatty acids were elevated in the experimental cheeses on d 1 because of inclusion of the EMC. Counts of NSLAB were also elevated in the experimental cheeses compared with the control cheese from the start of ripening. Levels of free AA were slightly elevated in the experimental cheeses at 1, 2, and 4 mo, but significantly greater accumulations were detected by 6 mo of ripening, with His, Leu, and glutamate reflecting the greatest increases. Levels of long-chain free fatty acids increased up to 2 mo, indicating an initial stimulation of lipolysis, but had decreased by 6 mo, indicating greater catabolism, probably caused by NSLAB and increased starter lysis. Principal component analysis of the volatile compounds showed few differences in the aroma profiles among the cheeses up to 4 mo of ripening, but a large separation of the cheeses supplemented with EMC relative to the control was observed by 6 mo. Sensory analysis of the cheeses with added EMC showed an acceleration of 2 mo in flavor development compared with the control cheese with the addition of 1 g/100 g of EMC developing a flavor profile at 4 mo similar to the control cheese at 6 mo of ripening. However, atypical Cheddar flavors developed on prolonged storage. This study shows the potential of adding EMC during Cheddar production to produce a fast-ripened ingredient-type Cheddar cheese.

Composition, sensory and shelf life stability analyses of Longissimus dorsi muscle from steers reared under organic and conventional production systems.

In recent years the demand for organically grown food has increased. In this study, organic (O, n=6) and conventionally (C, n=6) reared steers aged between 18 and 24 months were slaughtered during the month of September 2002. Four days post-slaughter, the Longissimus dorsi (LD) muscle was excised from the left side of each carcass. All muscles were vacuum packed and aged in a chill for a further seven days. Steaks were cut from each sample, and from these, lean meat was removed, blended and compositional analysis was carried out. O samples were significantly higher (P>0.05) in fat content and therefore were significantly (P>0.05) lower in moisture content than C samples. No significant differences were observed between C and O samples for protein, ash, ß-carotene, α-tocopherol or retinol. There was also no significant difference in fatty acid content between C and O samples. Colour stability and fat oxidative stability of samples were also measured, while stored under retail conditions. Samples were packed using both modified atmosphere packaging (MAP) and by overwrapping with cling film. MAP C samples had the best colour stability while overwrapped C samples had the best lipid stability. Therefore, colour and lipid stability of beef samples were influenced by sample composition and packaging format used, which resulted in C samples outperforming O samples with respect to shelf life stability.

Influence of starter culture on flavor and headspace volatile profiles of fermented whey and whey produced from fermented milk.

Rennet whey and skim milk were compared as media for fermentation by commercial cheese, yogurt, and probiotic starter cultures. Effect of culture, medium, and their interaction on flavor was assessed and compared by sensory descriptive analysis and headspace volatile analysis by proton transfer reaction-mass spectrometry. In general, the aroma of fermented whey was similar to that of whey separated from fermented milk, indicating a favorable possibility of substituting milk with whey in the manufacture of fermented milk-like beverages. Starter culture significantly affected most sensory characteristics of the products. Key volatile compounds for the characteristic flavor of yogurt, such as acetaldehyde and diacetyl, were not significantly affected by medium when fermented with the yogurt culture, and reached similar levels in both systems. Volatile analysis results were consistent with the results of the sensory evaluation, indicating the high reliability of proton transfer reaction-mass spectrometry in detecting important volatile compounds for aroma. Integration of this sensory and chemical information allows a better understanding of how flavor and related compounds are affected by ingredients or processing, which may be useful for the development of value-added whey products.

Sensory characteristics and related volatile flavor compound profiles of different types of whey.

To characterize the flavor of liquid whey, 11 samples of whey representing a wide range of types were sourced from cheese and casein-making procedures, either industrial or from pilot-plant facilities. Whey samples were assessed for flavor by descriptive sensory evaluation and analyzed for headspace volatile composition by proton transfer reaction-mass spectrometry (PTR-MS). The sensory data clearly distinguished between the samples in relation to the processes of manufacture; that is, significant differences were apparent between cheese, rennet, and acid wheys. For Mozzarella and Quarg wheys, in which fermentation progressed to low pH values, the starter cultures used for cheese making had a significant influence on flavor. In comparison, Cheddar and Gouda wheys were described by milk-like flavors, and rennet casein wheys were described by "sweet" (oat-like and "sweet") and thermally induced flavors. The volatile compound data obtained by PTR-MS differentiated the samples as distinctive and reproducible "chemical fingerprints". On applying partial least squares regression to determine relationships between sensory and volatile composition data, sensory characteristics such as "rancid" and cheese-like odors and "caramelized milk," yogurt-like, "sweet," and oat-like flavors were found to be related to the presence and absence of specific volatile compounds.

Interactions between texture and trigeminal stimulus in a liquid food system: effects on elderly consumers preferences.

Changes to the chemical senses of taste and smell that accompany ageing are widely believed to influence food preferences and consumption in the elderly. The possibility that interactions between the residual senses of texture and trigeminal perception can compensate for specific losses was explored using a complex liquid food system, soup. A consumer panel of twenty-four young people (20-35, mean age 27.7 +/- 3.95 years) and twenty-four elderly people (>65 years, mean age 73.6 +/- 5.78 years) were used for preference tests. Eight soups were prepared using a standardised recipe, with four variations in texture and two levels of trigeminal stimulus. The consumer panel preferences were measured using a nine point hedonic scale. The hedonic data was corrected for a scaling effect, and principle components analysis was completed on the normalised data of the two age cohorts. The preference decision of both age groups was in the direction of the lower level of trigeminal stimulation. Overall the older panel was less discriminating than the younger panel. However the older panel made an attempt to grade the different textures while the younger panel seemed to ignore the textural attribute in their preference decision. The older panel's preference decreased as the thickness of the soups increased across trigeminal levels. These results suggest that perhaps a judicious selection of a certain texture or mouthfeel combined with a preferred level of trigeminal irritation could boost elderly food enjoyment. Finally, a postal questionnaire was circulated to gain an insight in to the consumer's background and thus partially explain the motivation for their preferences.

Interactions between artificial saliva and 20 aroma compounds in water and oil model systems.

The interactions between saliva components and 20 aroma compounds in water and oil model systems were systematically evaluated as a function of saliva composition and saliva/model system ratio. Air/liquid partition coefficients of dimethyl sulfide, 1-propanol, diacetyl, 2-butanone, ethyl acetate, 1-butanol, 2-pentanol, propyl acetate, 3-methyl-1-butanol, ethyl butyrate, hexanal, butyl acetate, 1-hexanol, 2-heptanone, heptanal, alpha-pinene, 2-octanone, octanal, 2-nonanol, and 2-decanone were determined by static headspace gas chromatography. Chain length of compounds within the homologous series determined the extent of interactions with the model system or saliva. Salts in the artificial saliva hardly interacted with aroma compounds. On the other hand, saliva proteins lowered retention of highly volatile compounds and increased retention of less volatile, hydrophobic compounds. Significant differences in volatility of compounds when artificial saliva or water was added indicated that saliva could not be sufficiently replaced by water. The model system/saliva ratio influenced air/liquid partitioning of the aroma compounds significantly for both model systems. Although saliva composition affected volatility of the aroma compounds, the saliva/model system ratio was of much greater influence.

Finnish-type aspartylglucosaminuria detected by oligonucleotide ligation assay.

Aspartylglycosaminuria (AGU) is a recessively inherited lysosomal storage disease that occurs with much higher frequency in Finland than elsewhere. AGU is caused by a deficiency in glycosylasparaginase (GA), which results in the accumulation of glycoasparagines in lysosomes. In the Finnish population, a single nucleotide change in the gene encoding GA is responsible for the disease. We have used the oligonucleotide ligation assay (OLA) to detect the mutation in polymerase chain reaction (PCR)-amplified DNA samples from normal, carrier, and affected individuals. Screening for AGU among 415 random Finnish DNA samples with PCR/OLA revealed five carriers of the mutant allele and demonstrated the potential of the method for use in carrier screening. PCR/OLA provides a rapid, reliable, nonisotopic method to detect the mutation responsible for AGU that can readily be applied to large population screening.

pH shifts and precipitation associated with metal ions in tissue culture.

Recently there has been interest in tests to assess the physiological response to surgical implant corrosion products. Both cell culturing in metal-bearing solutions and intramuscular injection of such solutions have been carried out. This paper examines the effects of the constraints of multicomponent equilibrium conditions on the characteristics of the solutions used in these biocompatibility tests. It is demonstrated that, unbuffered, they will have pH values shifted from neutral and that, in the buffered state, these solutions may contain both dissolved metal ions and insoluble hydroxides. The implications of these characteristics for the interpretation of the results of biocompatibility tests are discussed.