Per Lea

Preference for tomatoes, affected by sensory attributes and information about growth conditions

Abstract The study concerns perceived effects of product attributes and product information on preference for ecologically as compared to conventionally grown tomatoes. A selected, trained panel described 13 tomato varieties to find as broad a basis for sensory variation as possible. Latent structures were extracted as a combination of sensory attributes and product information in a preference test. Two samples of each growing system were selected. A blind preference test was performed, and then another with either correct or false information about the growing system. Preference was influenced not only by tomato perception, but also by product information.

Consumer perceptions of pork in Denmark, Norway and Sweden

Abstract This study focused on how the consumer perceived the eating quality of pork. Detailed questionnaires were distributed to pork consumers (n=526) in Denmark, Norway and Sweden. Multivariate statistical techniques were applied to investigate differences among the consumers. The consumers ranked flavour as the most important attribute. The most important reason for buying pork was its suitability for many dishes, and the least important reason was for serving pork at social occasions. The major differences among consumers occurred between countries and to a lesser extent within age and genders. Swedish consumers reported a higher consumption frequency and were more satisfied with pork quality (i.e. tenderness and juiciness) compared with Norwegian consumers (more aware of rancidity) and Danish consumers (more aware of tasteless flavour). Consumption frequency was related to texture and off-flavour. Consumers aged 16–35 were less likely to eat pork than those older than 35 years.

Survival and growth of Escherichia coli O157:H7, Yersinia enterocolitica and Salmonella enteritidis on decontaminated and untreated meat

Decontamination of meat or carcasses may have an effect in reducing the number of pathogens. Recontamination with other pathogens during cutting or packaging may, however, result in higher growth on decontaminated than on untreated meat due to the lack of competing non-pathogenic microorganisms. In this study we compared the growth of pathogens during storage at 10°C (worst case condition) on untreated meat and meat that had been decontaminated by steam vacuuming combined with spraying with 0.2 M lactic acid. Salmonella enteritidis inoculated on chicken multiplied quickly and reached log 7 cfu per cm(2) after 4 days of aerobic storage at 10°C, but growth was not significantly higher on decontaminated than on untreated chicken. The number of Yersinia enterocolitica inoculated on decontaminated pork skin reached log 9 cfu per cm(2) after 5 days of aerobic storage at 10°C. Overall, growth on vacuum-packed decontaminated and untreated pork under the same conditions was not significantly different, although there tended to be less growth on the untreated samples. The number of Escherichia coli O157:H7 on decontaminated beef increased by nearly 3 log cycles after 5 days of aerobic storage at 10°C compared to only a 1 log cycle increase on untreated beef. For the vacuum-packed beef, growth of E. coli O157:H7 on the fresh meat was very slow, while there was about a 3 log increase on the decontaminated beef. A higher average growth on the decontaminated beef was also found in an experiment with a very low inoculum (27 cfu per cm(2)). During storage of vacuum-packed samples there was multiplication of E. coli O157:H7 on the decontaminated beef, but virtually none on the untreated beef. This study shows that multiplication of S. enteritidis on chicken and Y. enterocolitica on pork skin was not significantly higher on decontaminated compared to untreated meat. The increased multiplication of E. coli O157:H7 on decontaminated beef, especially when vacuum-packed, gives cause for concern. Preventive measures might be a strict HACCP approach to the handling of the decontaminated meat before packaging or use of a protective culture of lactic acid bacteria.

Near infrared reflectance spectroscopy in the prediction of sensory properties of beef

Near infrared (NIR) spectroscopy in the prediction of sensory hardness, tenderness and juiciness of bovine M. Longissimus dorsi muscles has been studied. Principal component regressions (PCR) of sensory variables from NIR reflectance measurements on frozen/thawed beef of 120 heat treated samples yielded multivariate correlation coefficients of cross-validation of 0.74, 0.70 and 0.61 for hardness, tenderness and juiciness, respectively. The corresponding correlation coefficients for NIR measurements of fresh (non-frozen) samples were approximately 0.1 units lower for all sensory variables. Predicting Warner Bratzler (WB) shear press values from NIR measurements gave a correlation coefficient similar to that for prediction of sensory hardness. The univariate correlation coefficient between sensory hardness and WB shear press values was 0.90.

Influence of beef carcass stretching and chilling rate on tenderness of m. longissimus dorsi.

Sides of 31 non-stimulated carcasses of young bulls were subjected to the muscle stretching methods Tenderstretch (TS) by pelvic bone suspension or Tendercut (TC) with two skeletal cuts or served as controls by traditional Achilles tendon suspension. The sides were chilled at fast and medium rates, resulting in temperatures of 4-5 and 9°C in the m. longissimus dorsi (LD) at 10 h post mortem. The LDs were examined for sarcomere length, Warner-Bratzler peak shear force and sensory properties after 8 days of ageing at 4°C. At the fast chilling rate, TS and TC increased sarcomere lengths, reduced shear force and improved sensory tenderness of the LDs compared to the controls (P<0.05). At the medium chilling rate, sarcomere lengths increased (P<0.05), but no significant differences were found in shear force or sensory tenderness (P>0.05) of the muscles due to stretching. However, the medium chilling rate was efficient in producing tender LDs without applying muscle stretching methods. TS and TC are feasible alternatives for improving overall tenderness and reducing variation in tenderness of beef LD at cold shortening chilling conditions.

The effect of temperature on sensory quality, chemical composition and growth of carrots (Daucus carota L.) I. Constant diurnal temperature

SummaryThe carrot cv. Panther FT grown in phytotrons at 9,12 15,18 and 21°C constant diurnal temperatures at two locations, As (59°40’N) and Tromso (69°39’N), and harvested at two dates was evaluated for sensory attributes, chemical composition and morphological variates. Significant temperature effects were detected for most sensory, chemical and physical variables. High growing temperatures (18 and 21°C) favoured colour, bitter tasting flavour components, firmness and the dry matter, sucrose and carotene content of the roots, whereas low growing temperature (9 and 12°C) heightened sweet taste, acidic taste, crispness, juiciness, and the fructose and glucose content. The longest roots were obtained at 9 and 12°C, the highest root weights at 12 and 15°C. Principal component analysis (PCA) revealed clear differences in the sensory profile of carrots grown at high and low temperatures, expressed by the first three principal components which together explained 81% of the variation in sensory variables. PCA o...

Variable selection in PCA in sensory descriptive and consumer data

This paper presents a general method for identifying significant variables in multivariate models. The methodology is applied on principal component analysis (PCA) of sensory descriptive and consumer data. The method is based on uncertainty estimates from cross-validation/jack-knifing, where the importance of model validation is emphasised. Students t-tests based on the loadings and their estimated standard uncertainties are used to calculate significance on each variable for each component. Two data sets are used to demonstrate how this aids the data-analyst in interpreting loading plots by indicating degree of significance for each variable in the plot. The usefulness of correlation loadings to visualise correlation structures between variables is also demonstrated.

Effects of carbon dioxide on yield, texture and microstructure of cooked ground beef.

The objective of the study was to find the effects of CO(2) gas on cooking loss, instrumental hardness and microstructural changes of ground beef heated to 70-83 °C. In two experiments, ground beef was stored for 4 days in 60% CO(2)/39.6% N(2)/0.4% CO and vacuum (1), or in 100% CO(2), 50% CO(2)/50% N(2), 20% CO(2)/80% N(2), 100% N(2) and vacuum (2). In an additional experiment, slices of beef semimembransosus muscles were stored for 10 days in 100% CO(2), 100% N(2) and vacuum. Cooking loss of ground beef patties was higher of all CO(2) treatments than non-CO(2) treatments (p<0.05). Storage of raw ground beef in CO(2) caused a concentration dependent decrease in raw meat pH of up to 0.12 units in 100% CO(2). In the beef slices, small CO(2) related fissures and pores were formed in the cooked meat. These changes in pH and microstructure probably contributed to the elevated cooking loss. The hardness of cooked ground beef was not affected by CO(2) exposure (p>0.05). Because CO(2) in concentrations of 20-100% is commonly used in industrial packaging processes for retail meat and meat trimmings, a reduction in cooking yield of 1-3% may have sensory and economic implications.

Measuring validity in sensory analysis

Abstract Two methods for assessor evaluation are demonstrated, both based on graphical techniques: plots of an assessors ability to detect differences vs. his/her repeatability, and the ‘egg-shell plot’ which highlights an assessors agreement with the panels rankings. The methods presented in this paper are modifications of already established methods in the area. All methods are illustrated by an example from sensory profiling of beef boullion.

Effects of temperature and photoperiod on sensory quality and contents of glucosinolates, flavonols and vitamin C in broccoli florets

Broccoli is grown around the world at a wide range of photoperiods and temperatures, which may influence both sensory quality and phytochemical contents. Florets produced in phytotron and at two semi-field sites (70 °N and 58 °N) were examined for effects of contrasting temperatures and photoperiods on sensory quality and contents of glucosinolates, flavonols and vitamin C. Growth conditions associated with high northern latitudes of low temperature and long photoperiods, produced bigger floral buds, and florets with sweeter taste and less colour hue than more southern conditions. The contents of vitamin C did not vary, while the response of individual glucosinolates varied with temperature and day length, and contents of quercetin and kaempferol were lower in phytotron than under semi-field conditions. Thus, our results show that contrasting temperatures and photoperiods influence the sensory quality of broccoli florets, while contents of different bioactive phytochemicals are not influenced in a unidirectional pattern.