Imagined eating - An investigation of priming and sensory-specific satiety.

While obesity remains a pressing issue, the wider population continues to be exposed to more digital food content than ever before. Much research has demonstrated the priming effect of visual food content, i.e., exposure to food cues increasing appetite and food intake. In contrast, some recent research points out that repeated imagined consumption can facilitate satiate and decrease food intake. Such findings have been suggested as potential remedies to excessive food cue exposure. However, the practically limitless variety of digital food content available today may undermine satiation attempts. The present work aims to replicate and extend prior findings by introducing a within-subjects baseline comparison, disentangling general and (sensory-) specific eating desires, as well as considering the moderating influence of visual and flavour stimulus variety. Three online studies (n = 1149 total) manipulated food colour and flavour variety and reproducibly revealed a non-linear dose-response pattern of imagined eating: 3 repetitions primed, while 30 repetitions satiated. Priming appeared to be specific to the taste of the exposed stimulus, and satiation, contrary to prior literature, appeared to be more general. Neither colour nor flavour variety reliably moderated any of the responses. Therefore, the results suggest that a more pronounced variety may be required to alter imagery-induced satiation.

Lactic acid bacteria associated with a heat-processed pork product and sources of variation affecting chemical indices of spoilage and sensory characteristics.

AIMS: To evaluate the potential for developing a quality index for a Danish modified atmosphere packaged (MAP) heat-processed and naturally contaminated pork meat product stored at 5 degrees C. METHODS AND RESULTS: The composition of the predominating microflora and changes in contents of tyramine, arginine, organic acids and sensory characteristics were analysed. The microflora was predominated by Lactobacillus sakei, Leuconostoc carnosum and Carnobacterium divergens. The presence of each species varied between products and batches resulting in limited usefulness of the concentrations of these bacteria or their metabolites as indices of quality. Furthermore, the three species differed in their metabolic activities as shown by use of a model meat extract. However, when MAP storage of the processed pork product was followed by aerobic storage then acetic acid showed some potential as a chemical indicator of sensory quality. CONCLUSION: Variation in processing parameters and spoilage microbiota limited the usefulness of concentrations of micro-organisms and their metabolites as indices of spoilage for the studied processed MAP pork product. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study contributes to an understanding of the difficulties experienced in developing quality indices to be used in the control of microbial spoilage of processed MAP meat products.

Evaluation of pork colour sensory colour assessment using trained and untrained sensory panellists.

M. longissimus dorsi and M. psoas major minced pork patties from three dietary treatment groups of DLY (Duroc/Landrace/Yorkshire) cross bred pigs were packaged in polythene bags and placed in a retail refrigerated display cabinet at 5±1 °C, under fluorescent light (1000 lux) for up to 5 days. Each dietary treatment group consisted of pigs (n=7) fed either a low vitamin E diet (80 mg dl-α-tocopheryl acetate/kg of feed), supplemental iron [7 g iron (II) sulphate/kg feed] or supplemental vitamin E (200mg dl-α-tocopheryl acetate/kg of feed)+supplemental iron. Samples were subjected to visual colour evaluation by a trained sensory panel (n=8) and an untrained panel (n=8) on days 0, 1, 3 and 5 of display. The signal to noise (S/N) ratios for assessors and replicates for the trained assessor group were higher than those of the untrained assessor group indicating greater reliability in the trained assessor results. The trained assessor group produced relatively normal percentile distributions for sensory terms in the assessment of both M. longissimus dorsi and M. psoas major muscles. The untrained assessor group displayed more skewed or non-symmetric distributions for M. longissimus dorsi, but produced a normal distribution for M. psoas major. Quantitative and qualitative analysis of the sensory profiling by both the trained and untrained groups of test subjects showed that in general sensory training contributed to a more effective visual sensory evaluation of M. longissimus dorsi in terms of metmyoglobin development. However, this is not the case for M. psoas major where both groups of assessors produced comparable results. Use of uniploar scaling did not improve the discriminative ability of assessors, both trained and untrained, in assessment of blue and yellow. The untrained group of assessors were even less effective in the use of these scales. It appeared that the sensory visual assessment of meat products can be performed effectively without training when the product colour is familiar to the assessors. However, training of panellists becomes relevant when a more unfamiliar product of unfamiliar colour is to be assessed and the unintuitive aspect of discrimination may play a greater role in the objective sensory colour assessment of meat.

Warmed-over flavour in porcine meat - a combined spectroscopic, sensory and chemometric study.

The effectiveness of applying rapid spectral techniques in the prediction of meat quality in relation to pre-slaughter stress and warmed-over flavour (WOF) was investigated. The effect of pre-slaughter stress on the development of WOF is a relatively new area of interest in WOF research. The present study investigated the relationship between pre-slaughter stress and WOF characteristics (after 0 to 5 days' storage) in porcine meat as evaluated by chemical, sensory and spectroscopic methods. Sensory evaluation, visual reflectance spectroscopy (VIS) and low-field (1)H NMR (LF-NMR) proved efficient in describing the different stress groups and the storage period, whereas fluorescence spectroscopy and the TBARS test were only able to follow WOF during storage. Near Infrared Reflectance (NIR) and Raman scatter showed a very weak relationship to pre-slaughter stress and levels of WOF during storage. Good correlations (up to r=0.93) of sensory terms were achieved with VIS and fluorescence spectroscopy and LF-NMR.

Sensory colour assessment of fresh meat from pigs supplemented with iron and vitamin E.

Pork muscle samples (M. longissimus dorsi) were obtained from pigs given one of four dietary treatments: (1) control diet; (2) supplemental iron [7-g iron (II) sulphate/kg feed]; (3) supplemental vitamin E (200-mg dl-α-tocopheryl acetate/kg of feed); and (4) supplemental vitamin E+supplemental iron. Muscle cores were packaged in polythene bags and placed in a retail refrigerated display cabinet at 5±1°C, under fluorescent light (1000 LUX) for up to 5 days. Samples were subjected to visual colour evaluation by a trained sensory panel (n=12) at 0, 1, 3 and 5 days. In addition instrumental L*, a* and b* values and drip loss were measured on each day of analysis. All samples became less red and browner over storage time in the refrigerated display cabinet. The vitamin E treated samples were more red and less brown compared with the other samples on successive days in the cabinet followed by the control, iron/vitamin E and iron treatments. The iron/vitamin E treatment was positioned midway between the vitamin E and iron treatments indicating that the vitamin E in the samples was effective in reducing the pro-oxidative effect of iron in inducing the brown metmyoglobin pigment development. Iron supplementation did not significantly (P<0.05) increase M. longissimus dorsi iron tissue levels, but had a detrimental effect on the visual sensory properties of the iron and iron/vitamin E treatment groups with greater metmyoglobin formation. Vitamin E appears to have promoted non-supplemental iron absorption in the vitamin E treated group without the detrimental sensory colour characteristics associated with ferrous sulphate supplementation. Drip loss increased in all samples during the course of the experiment with no significant (P<0.05) differences between the experimental groups. The panellists were able to differentiate the four experimental groups on each day of the study and were more effective in evaluating the colour quality of samples than instrumental assessment, i.e. the Hunter L* a* b* method.

Sensory and chemical investigations on the effect of oven cooking on warmed-over flavour development in chicken meat.

Descriptive sensory profiling was carried out to evaluate the effect of oven-cooking temperature (160, 170, 180, 190 °C) on warmed-over flavour (WOF) development in cooked, chill-stored (at 4 °C for 0, 1, 2 and 4 days) and reheated chicken patties, derived from M. pectoralis major. In addition, gas chromatography-mass spectrometry (GC-MS) was carried out on a representative sub-set (160, 180, 190(o)C, stored at 4 °C for 0, 1, 4 days) of the meat samples used in sensory profiling. The effects of cooking and WOF in the sensory and chemical data were analysed using multivariate ANOVA-Partial Least Squares Regression (APLSR). Descriptive profiling indicated that WOF development was described by an increase of 'rancid' and 'sulphur/rubber' sensory notes and a concurrent decrease of chicken 'meaty' characteristics. Increasing cooking temperature resulted in meat samples with a more 'roasted', 'toasted' and 'bitter' sensory nature. Moreover, the 'roasted' character of the meat samples was also related to WOF development. Analysis of the volatile compounds from the chicken patties showed a rapid development of lipid oxidation derived compounds with chill-storage. Such compounds most likely contributed to the 'rancid' aspect of WOF development. Moreover, changes in sulphur-containing compounds were also related to WOF development and were proposed as additional participants in the lipid oxidation reactions. The sensory effects of these compounds were mainly described by the 'sulphur/rubber' note associated with WOF development. Overall, cooking temperature was found to increase the formation of Maillard-derived compounds, however, these did not appear to inhibit WOF development in the chicken patties.

Descriptive sensory profiling and physical/chemical analyses of warmed-over flavour in pork patties from carriers and non-carriers of the RN(-) allele.

Descriptive sensory profiling was carried out to evaluate warmed-over flavour (WOF) development in cooked, chill-stored and reheated pork patties derived from the meat (Musculus longissimus dorsi) of carriers (RN(-)/rn(+)) and non-carriers (rn(+)/rn(+)) of the RN(-) gene. Patties were oven-cooked at 150 and 170 °C and chill-stored for up to 5 days to facilitate warmed-over flavour (WOF) development. In addition, thawing losses, cooking losses, pH and TBARS were measured in the cooked pork patties. Analysis of variance (ANOVA) was used to investigate changes in the physical/chemical measurements due to the experimental design variables (storage days, cooking temperature and genotype) and multivariate ANOVA-partial least squares regression (APLSR) was used to determine relationships between the design variables and the sensory and physical/chemical data. WOF was found to involve the development of lipid oxidation derived nuance off-flavour and odour notes, e.g. rancid-like flavour and linseed oil-like odour, in association with a concurrent decrease in 'meatiness' as described by, e.g. cooked pork meat-like flavour. Cooking temperature was described by roasted-like and caramel-like odours and samples from carriers of the RN(-) gene were described as more 'sour' and 'metallic'. Thawing and cooking losses were found to be significantly (P <0.05) higher in meat from carriers of the RN(-) gene versus non-carriers. pH was negatively related to samples from carriers of the RN(-) gene. However, the measured pH in RN(-) carriers could not be significantly ascribed as lower in non-carriers in the freshly cooked meat samples. TBARS were found to be significant (P <0.05) predictors of the sensory terms related to the lipid oxidation aspect of WOF. Moreover, TBARS were significantly (P <0.05) higher in meat from RN(-) gene carriers but, significantly (P <0.05) lower in meat cooked at high oven temperatures (170 °C). The former effect was postulated as related to pH and the latter as related to the antioxidant effects of Maillard reaction products developed at higher cooking temperatures. Overall, WOF, cooking temperature and genotype were differentiated as individual dimensions through sensory profiling of the meat samples and each source of variation was characterised by specific groups of sensory descriptors. Moreover, the predictive nature of thawing losses, cooking losses and TBARS was established for the effects of RN(-) gene, cooking temperature and WOF, respectively.

Sensory and chemical assessment of pork supplemented with iron and vitamin E.

Pork muscle samples (M. longissimus dorsi and M. psoas major) were obtained from pigs given one of four dietary treatments, (1) control diet, (2) supplemental iron (7g iron (II) sulphate/kg feed), (3) supplemental vitamin E (200 mg dl-α-tocopheryl acetate/kg of feed) and (4) supplemental vitamin E+supplemental iron. Vitamin C was supplemented to all dietary treatments to facilitate iron uptake. Vitamin E and iron tissue levels were determined for each treatment. Warmed-over flavour (WOF) was evaluated by a trained sensory panel (n=8) for the four treatments which were cooked and refrigerated at 4 °C for up to 5 days. Thawing loss, driploss and thiobarbituric acid reactive substances (TBARS) were also determined. Vitamin E muscle tissue levels were greatest in the Iron/vitamin E-treated group followed by the vitamin E group, control and iron treated groups, respectively for M. longissimus dorsi. Whereas, for M. psoas major vitamin E tissue levels were in order of magnitude, vitamin E>iron/vitamin E>iron>control group. Iron tissue levels were in the order vitamin E>iron/vitamin E>control>iron for M. longissimus dorsi and iron>vitamin E>control>iron/vitamin E for M. psoas major. Thus, vitamin E and vitamin C promoted non-supplemental iron absorption in the vitamin E-treated group for M. longissimus dorsi and to a lesser extent for M. psoas major. M. psoas major was more susceptible to warmed-over flavour development than M. longissimus dorsi for all treatments as determined by sensory profiling, due to higher tissue iron levels. From sensory profiling, WOF development in M. longissimus dorsi and M. psoas major was highest in the iron-supplemented groups followed by the control and vitamin E-supplemented groups.

A comparison of warmed-over flavour in pork by sensory analysis, GC/MS and the electronic nose.

Pork muscle samples (M. longissimus dorsi and M. psoas major) were obtained from pigs given one of 4 dietary treatments, (i) control diet, (ii) supplemental iron (300 mg iron (II) sulphate/kg feed), (iii) supplemental vitamin E (200 mg dl-α-tocopheryl acetate/kg of feed) and (iv) supplemental vitamin E+supplemental iron. Warmed-over flavour (WOF) was evaluated by a trained sensory panel (n=8) for the four treatments cooked and refrigerated at 4 °C for up to 5 days. Gas chromatography mass spectrometry (GC/MS) and Electronic nose analysis was performed on a subset of the full design which included samples of M. longissimus dorsi, treatments (ii) and (iii) and M. psoas major with treatment (i) for 0 days of WOF development. Day 5 of WOF development was included in the subset and represented by samples of M. longissimus dorsi, treatment (iv) and M. psoas major, treatments (ii) and (iii). Bi-linear modeling was used to determine the correlation of GC/MS and electronic nose data to sensory data. Also, the reproducibility and reliability of electronic nose data was evaluated by repeating the analysis of samples in a different laboratory and with a time difference of approximately 11 months. Mean-centring was used to normalise the data from these two different electronic noise data sets. GC/MS data correlated to sensory data with specific compounds (e.g., pentanal, 2-pentylfuran, octanal, nonanal, 1-octen-3-ol and hexanal), proving to be good indices of oxidation in cooked samples of M. longissimus dorsi and M. psoas major. Electronic nose data correlated to sensory data and separated the sensory variation. The reproducibility of this data was high with the second set of samples being predictive of the first set.

Sensory and chemical analysis of cooked porcine meat patties in relation to warmed-over flavour and pre-slaughter stress.

Two independent sensory profiles were carried out to evaluate warmed-over flavour (WOF) development in cooked, chill-stored and reheated pork patties. The patties were derived from the Musculus semimembranosus of animals subjected to different pre-slaughter stress treatments. All patties were stored in oxygen permeable bags at 4°C for 0, 1, 2, 3 and 5 days to facilitate WOF development. In addition, thiobarbituric acid reactive substances (TBARS), conjugated dienes, pH, water content, total lipids and the fatty acid compositions of phosphatidyl choline (PC), phosphatidyl ethanolamine (PE) and total lipids, were measured in the cooked meat patties. A data analytical strategy involving Analysis of Variance-Partial Least Squares Regression (ANOVA-PLSR), to determine relationships between the design variables (WOF and pre-slaughter stress) and the sensory-chemical data, and PLSR to elucidate predictive links between the sensory and chemical data was utilised. WOF was found to involve the development of lipid oxidation derived nuance off-flavour and odour notes, e.g. rancid-like flavour and linseed oil-like odour, in association with a concurrent decrease in cooked pork meat-like flavour. The reduction in "meatiness", over the initial days, 0-2 of WOF development was attributed to the degradation of both, unstable sulfur-containing amino acids in meat proteins and sulfur-containing "meaty" aroma compounds. Whereas, at the later days, 3-5 of WOF development the "meaty" loss was ascribed to perceptual masking by lipid oxidation products. TBARS and conjugated dienes were found to be significant (P<0.05) predictors of the sensory terms related to the lipid oxidation aspect of WOF. Whilst the polyunsaturated fatty acid (PUFAs) contents of PE, PC and the total lipids were found to decrease with WOF development, reflecting their loss in lipid oxidation reactions. The sensory variation related to pre-slaughter stress appeared to be distinct from WOF variation and was described by a sour to sweet taste continuum. However, interactions were noted that indicated increasing pre-slaughter stress resulted in a decreased sensory perception of WOF. Moreover, pH and water content were found to significantly (P<0.05) predict the sensory effects resulting from pre-slaughter stress.

Consumer and sensory investigations in relation to physical/chemical aspects of cooked pork in Scandinavia.

The present study addresses sensory quality and liking for pork (eight samples) varying in quality due to adrenaline injection resulting in elevated ultimate pH post-slaughter (24h), meat ageing, cooking temperature and warmed-over flavour (WOF) among consumers (n=288) in Scandinavia. The consumers preferred meat with higher pH (pH(24h)=6.0), cooked to the lowest temperature (65 °C versus 80 °C). Consumers least preferred samples with WOF described as metallic, acidic and off-flavour by a trained panel. "Elevated pH(24h) meat" cooked to 65 °C resulted in a more sweet and tender meat. Juiciness, tenderness and the absence of off-flavour were the most important characteristics for consumers' liking of pork. Consumption frequency and liking of pork were positively related. The consumers that were most satisfied with pork quality reported highest consumption frequency. Elderly people and males expressed the highest liking score and consumption frequency, respectively.

Evaluation of pork colour: prediction of visual sensory quality of meat from instrumental and computer vision methods of colour analysis.

M. longissimus dorsi minced pork patties from three dietary treatment groups of DLY (Duroc/Landrace/Yorkshire) cross bred pigs were packaged in polythene bags and placed in a retail refrigerated display cabinet at 5 °C±1 °C, under fluorescent light (1000 lux) for up to 5 days. Each dietary treatment group consisted of pigs (n=7) fed either a low vitamin E diet (80 mg dl-α-tocopheryl acetate/kg of feed), supplemental iron (7 g iron (II) sulphate/kg feed) or supplemental vitamin E (200mg dl-α-tocopheryl acetate/kg of feed) + supplemental iron). Samples were subjected to visual colour evaluation by a trained sensory panel (n=8) and an untrained panel (n=8) on days 0, 1, 3 and 5. Instrumental Hunter L(∗), a(∗) and b(∗) values were measured on each day of analysis using a Minolta colorimeter. In addition RGB (red, green and blue) and Hunter L(∗), a(∗) and b(∗) values were measured using a digital camera. The use of trained and untrained panellists are both relevant in the visual assessment of meat products. In a previous study O'Sullivan, Byrne, and Martens (2003) indicated that the untrained panellist is analogous to the consumer and how they perceive colour changes in meat. However, the trained panellist is useful in the assessment of unfamiliar products and where a greater degree of discrimination is required. The order of oxidation of the experimental treatments was Control (low vitamin E)

Does the mind reflect the mouth? Sensory profiling and the future.

Descriptive Sensory Profiling methods have been used for over half-a-century. As the application of these methods obviously does not occur in a vacuum, we sketch the contextual basis of these methods. A unifying model, illustrating the tasks required from a sensory panellist, is presented with the aim of illuminating some major differences between methods. The history and main developments in the field of descriptive sensory profiling are outlined in a basic pedigree of methods. The authors suggest an approach to sensory profiling where taylor-made, problem oriented, methods are devised and used.

Low-temperature storage of bone marrow in nitrogen vapor-phase refrigerators: decreased temperature gradients with an aluminum racking system.

Large temperature gradients may exist in nitrogen vapor-phase refrigerators. Cryopreserved cells stored at higher levels may be considerably warmer than those stored closer to the liquid nitrogen reservoir. To decrease this temperature gradient, racking systems constructed of aluminum were placed in marrow storage refrigerators. The higher heat conductivity of aluminum resulted in a vapor-phase temperature gradient of only 5.9 degrees C at 22.5 inches above the liquid, as compared to the gradient of 86 degrees C seen with steel frames in a similar refrigerator. Temperature fluxes were minimal with lid opening or nitrogen filling. The thicker frame size and loss of the lowest storage level resulted in a storage capacity 63 percent of that achievable with steel frames and liquid immersion. Consumption of nitrogen was estimated to be 174 to 220 percent of the static usage in this model of refrigerator with 6 inches of nitrogen, but comparable to the consumption expected with full immersion of the racking system, regardless of frame construction. These data demonstrate the feasibility of achieving very low, stable, cryogenic temperatures in a vapor-phase refrigerator.