ROC curve analysis to determine effects of repetition on the criteria for same-different and A Not-A tests

Judges performed over 2000 same-different tests followed by over 2000 A Not-A tests, to distinguish between ‘threshold’ sodium chloride solutions and purified water. Fitting ROC curves to the data indicated that three out of four judges used a τ-strategy for the same-different test. The hypothesis that judges might, with experience, start to categorize the stimuli and switch to a β-strategy was generally not confirmed. On changing to the A Not-A method, half the judges appeared to continue initially to use the τ-strategy. The hypothesis that judges might make comparisons with the preceding stimulus rather than the standard stimulus, because of prior extensive experience with the same-different test, was generally not confirmed. Yet, in all cases there were exceptions.     

Comparison of rapid tests for assessing UHT milk sterility

Samples of UHT milk were contaminated at two levels (10(2) and 10(4) cfu/ml) with 52 bacterial strains associated with spoilage. Samples were assayed, using various tests, to determine efficiency in detecting non-sterility after an incubation period shorter than that advised in standard procedures. The tests performed were colony count, titratable acidity and pH modification, organoleptic assessment, stability towards ethanol (68, 80 and 88% v/v), resazurin and nitrate reduction. After 3 d incubation at 30 degrees C every case was detected by the resazurin test with a good statistical probability (P = 0 x 999). Reliability was not so high in all other tests, even after 14 d incubation.     

Using biodynamic models to reconcile differences between laboratory toxicity tests and field biomonitoring with aquatic insects

Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity in the laboratory are considerably higher than those found to impact insect communities in the field. New approaches are therefore needed to better understand how and why insects are differentially susceptible to metal exposures. Biodynamic modeling is a powerful tool for understanding interspecific differences in trace metal bioaccumulation. Because bioaccumulation alone does not necessarily correlate with toxicity, we combined biokinetic parameters associated with dissolved cadmium exposures with studies of the subcellular compartmentalization of accumulated Cd. This combination of physiological traits allowed us to make predictions of susceptibility differences to dissolved Cd in three aquatic insect taxa: Ephemerella excrucians, Rhithrogena morrisoni, and Rhyacophila sp. We compared these predictions with long-term field monitoring data and toxicity tests with closely related taxa: Ephemerella infrequens, Rhithrogena hageni, and Rhyacophila brunea. Kinetic parameters allowed us to estimate steady-state concentrations, the time required to reach steady state, and the concentrations of Cd projected to be in potentially toxic compartments for different species. Species-specific physiological traits identified using biodynamic models provided a means for better understanding why toxicity assays with insects have failed to provide meaningful estimates for metal concentrations that would be expected to be protective in nature.     

Consumer data—Statistical tests for differences in dispersion

Three types of category or rank data, commonly obtained in consumer taste tests will be analysed via a ranks transformation followed by a partition of Pearson's X². These three types of data are: independent samples data with ties, related samples data without ties, and related samples data with ties. The data are summarized as two-way tables of counts, where some of the counts are zero or small. Thus Monte Carlo P values are appropriate. The partition of X² method places a number of common nonparametric statistics in the same family. All the examples relate to actual taste tests done at the CSIRO Food Research Laboratory.     

Laboratory tests for assessing efficacy of atoxigenic Aspergillus flavus strains as biocontrol agents

Biocontrol by competitive inhibition using atoxigenic Aspergillus flavus strains has been shown to be an effective method for controlling aflatoxin production in peanuts, maize and cottonseed. Selecting biocontrol strains is not straightforward, as it is difficult to assess fitness for the task without expensive field trials. Reconstruction experiments have been generally performed under laboratory conditions to investigate the biological mechanisms underlying the efficacy of atoxigenic strains in preventing aflatoxin production and/or to give a preliminary indication of strain performance when released in the field. The study here described was conducted in order to evaluate the potential of the different atoxigenic A. flavus strains, colonizing the corn fields of the Po Valley, in reducing aflatoxin accumulation when grown in mixed cultures together with atoxigenic strains; additionally, we developed a simple and inexpensive procedure that may be used to scale-up the screening process and to increase knowledge on the mechanisms interfering with mycotoxin production during co-infection.     

Psychographic measures and sensory consumer tests: When emotional experience and feeling-based judgments account for preferences

The aim of this study is to explore psychological and psychosocial individual differences in order to understand heterogeneous sensory preference clusters identified in consumer tests. We conducted two studies with 100 participants in each. Six seat car fabrics were rated on liking items. A questionnaire composed of the Affect Intensity Measure (AIM) [Larsen, R. J. (1984). Theory and measurement of affect intensity as an individual difference characteristic. Dissertation Abstracts International, 85, 2297B], the Rational-Experiential Inventory (REI), the Iowa–Netherlands Comparison Orientation Scale, (INCOM) [Gibbons, F. X., & Buunk, B. P. (1999). Individual differences in social comparison: Development of a scale of social comparison orientation. Journal of Personality and Social Psychology, 76, 129–142], and the Centrality of Visual Products Aesthetics (CVPA) [Bloch, P. H., Brunel, F. F., & Arnold, T. J. (2003). Individual differences in the centrality of visual product aesthetics: Concept and measurement. Journal of Consumer Research, 29, 551–565] was used. Two clusters of preferences were characterized by the AIM and REI measures. One group, “the velvet fabrics likers”, experienced emotions more intensely than the “non-velvet likers” who in turn, appeared to rely mostly on feelings in the judgment process. We discuss the possible influence of these psychological factors on the significance of sensory input used in the evaluation process.     

Comparison of the efficiency of triangle and tetrade tests for discrimination sensory analysis of food

The efficiencies of triangle and tetrade tests for discrimination between samples of closely resembling organoleptic properties were compared on a variety of food products. The tetrade test was found in most cases better than or at least equal to the triangle test and easy to carry out for both the experienced and unexperienced judges.     

Short communication: Discrimination between retail bovine milks with different fat contents using chemometrics and fatty acid profiling

We used a multivariate chemometric approach to differentiate or associate retail bovine milks with different fat contents and non-dairy beverages, using fatty acid profiles and statistical analysis. We collected samples of bovine milk (whole, semi-skim, and skim; n = 62) and non-dairy beverages (n = 27), and we analyzed them using gas-liquid chromatography. Principal component analysis of the fatty acid data yielded 3 significant principal components, which accounted for 72% of the total variance in the data set. Principal component 1 was related to saturated fatty acids (C4:0, C6:0, C8:0, C12:0, C14:0, C17:0, and C18:0) and monounsaturated fatty acids (C14:1 cis-9, C16:1 cis-9, C17:1 cis-9, and C18:1 trans-11); whole milk samples were clearly differentiated from the rest using this principal component. Principal component 2 differentiated semi-skim milk samples by n-3 fatty acid content (C20:3n-3, C20:5n-3, and C22:6n-3). Principal component 3 was related to C18:2 trans-9,trans-12 and C20:4n-6, and its lower scores were observed in skim milk and non-dairy beverages. A cluster analysis yielded 3 groups: group 1 consisted of only whole milk samples, group 2 was represented mainly by semi-skim milks, and group 3 included skim milk and non-dairy beverages. Overall, the present study showed that a multivariate chemometric approach is a useful tool for differentiating or associating retail bovine milks and non-dairy beverages using their fatty acid profile.     

Development of DNA markers for discrimination between domestic and imported beef

In the meat industry, correct breed information in food labeling is required to assure meat quality. Genetic markers provide corroborating evidence to identify breed. This paper describes the development of DNA markers to discriminate between Japanese and Australian beef. Two Bos indicus-specific markers and MC1R marker were used as possible candidate markers. Amplified fragment length polymorphism method was employed to develop additional candidate markers. The 1564 primer combinations provided three markers that were converted into single nucleotide polymorphisms markers for high-throughput genotyping. In these markers, the allele frequencies in cattle from both countries were investigated for discrimination ability using PCR-RFLP. The probability of identifying Australian beef was 0.933 and probability of misjudgment was 0.017 using six selected markers. These markers could be useful for discriminating between Japanese and Australian beef and would contribute to the prevention of falsified breed labeling of meat.     

Use of cold microfiltration retentates produced with polymeric membranes for standardization of milks for manufacture of pizza cheese

Pizza cheese was manufactured with milk (12.1% total solids, 3.1% casein, 3.1% fat) standardized with microfiltered (MF) and diafiltered retentates. Polymeric, spiral-wound MF membranes were used to process cold (<7°C) skim milk, and diafiltration of MF retentates resulted in at least 36% removal of serum protein on a true protein basis. Cheese milks were obtained by blending the MF retentate (16.4% total solids, 11.0% casein, 0.4% fat) with whole milk (12.1% total solids, 2.4% casein, 3.4% fat). Control cheese was made with part-skim milk (10.9% total solids, 2.4% casein, 2.4% fat). Initial trials with MF standardized milk resulted in cheese with approximately 2 to 3% lower moisture (45%) than control cheese (∼47 to 48%). Cheese-making procedures (cutting conditions) were then altered to obtain a similar moisture content in all cheeses by using a lower setting temperature, increasing the curd size, and lowering the wash water temperature during manufacture of the MF cheeses. Two types of MF standardized cheeses were produced, one with preacidification of milk to pH 6.4 (pH6.4MF) and another made from milk preacidified to pH 6.3 (pH6.3MF). Cheese functionality was assessed by dynamic low-amplitude oscillatory rheology, University of Wisconsin MeltProfiler, and performance on pizza. Nitrogen recoveries were significantly higher in MF standardized cheeses. Fat recoveries were higher in the pH6.3MF cheese than the control or pH6.4MF cheese. Moisture-adjusted cheese yield was significantly higher in the 2 MF-fortified cheeses compared with the control cheese. Maximum loss tangent (LT_max) values were not significantly different among the 3 cheeses, suggesting that these cheeses had similar meltability. The LT_max values increased during ripening. The temperature at which the LT_max was observed was highest in control cheese and was lower in the pH6.3MF cheese than in the pH6.4MF cheese. The temperature of the LT_max decreased with age for all 3 cheeses. Values of 12% trichloroacetic acid soluble nitrogen levels were similar in all cheeses. Performance on pizza was similar for all cheeses. The use of MF retentates derived with polymeric membranes was successful in increasing cheese yield, and cheese quality was similar in the control and MF standardized cheeses.     

Scandinavian consumer preference for beef steaks packed with or without oxygen

Beef steaks retail-packed with (80% O₂, 20% CO₂) or without oxygen (either skin-packed or gas-packed (69.6% N₂, 30% CO₂, 0.04% CO or 70% N₂, 30% CO₂)) were compared by consumers in Denmark (n = 382), Norway (n = 316) and Sweden (n = 374). Two pairs of two steaks – one steak packed in a high oxygen atmosphere and one packed without oxygen – were given to the consumers. They were instructed to prepare the steaks at home on two consecutive days, and two persons had to taste each steak. In Denmark, the oxygen-free packing was either gas packing with CO (69.6% N₂, 30% CO₂, 0.04% CO) or without CO (70% N₂, 30% CO₂), in Norway it was either gas packing with CO (69.6% N₂, 30% CO₂, 0.04% CO) or skin packing, and in Sweden it was either skin packing or gas packing without CO (70% N₂, 30% CO₂). The meat represented animals that were between 17 and 80 months old (Denmark) and young bulls (Norway and Sweden).     

Evidence for differences in mode of action between two related carbamate insecticides

Carbaryl (1-naphthyl N-methylcarbamate) and its N-acetyl derivative have been compared in respect of toxicity (LD₅₀), rates of kill and anticholinesterase activity in vitro and in vivo, using the honeybee as test organism. Results obtained indicate that carbaryl does not act solely on brain cholinesterase. Alternative suggestions are discussed, together with observations supporting the idea that the N-acetyl derivative iS metabolised to a more potent cholinesterase inhibitor.     

Suitability of instrumental analysis for the discrimination between wild-caught and conventionally and organically farmed shrimps

Shrimps, primarily Penaeus monodon and Litopenaeus vannamei, from organic and conventional farms and free-living stocks were purchased from the German market over 1 year. This study examined the applicability of established analytical methods for the confirmation of the correct labelling of shrimp products. After species identification of 77 shrimp products, the proximate composition, carotenoid pattern, fatty acid profile and stable isotopes of carbon and nitrogen in the lipids and/or the defatted dry matter (DDM) were determined. To differentiate between the three types of production (wild, organically farmed or conventionally farmed), parameters alone or in combination, partly derived by multivariate tests, were considered. Stable isotope ratio mass spectrometry allowed the differentiation between organically and conventionally farmed Litopenaeus vannamei using the combination of ?δ¹³C and δ¹⁵N_DDM values. The gas chromatographic analysis of fatty acids also distinguished between organically and conventionally farmed shrimp of this species. The ratio of the free astaxanthin configurational isomers in shrimp flesh, analysed by high-performance liquid chromatography (HPLC), was inadequate for any assignment, because of the apparent ability to alter the structure of the ingested carotenoids. Thus, a general differentiation of the three production types, irrespective of individual species, could not be achieved by any single method.     

Relationship between total mercury concentration and fish size in two pelagic fish species: implications for consumer health

Total mercury concentrations were determined in different size classes of two pelagic fish species of great commercial importance, horse mackerel (Trachurus trachurus) and Mediterranean horse mackerel (Trachurus mediterraneus), to evaluate the relationship between total mercury concentration and fish size and to determine whether any differences might affect the quantitative assessment of mercury exposure for consumers. Mercury concentrations in horse mackerel and in Mediterranean horse mackerel were between 0.16 and 2.41 microg g(-1) of weight wet (mean, 0.68 microg g(-1)) and between 0.09 and 1.62 microg g(-1) (mean, 0.51 microg g(-1)), respectively. The regression curves revealed a significant relationship between mercury concentration and fish size (length and weight) for both species. Concentrations exceeding the proposed limit for human consumption were observed in 33.3% of the samples of both species and were associated with larger specimens. The consumption of the larger specimens could lead to an increase in mercury exposure for consumers. Estimated weekly intakes, calculated on the basis of concentrations relative to each size class, revealed a high exposure associated with the consumption of fish larger than 30 cm (horse mackerel, 11.63 to 20.16 microg/kg of body weight; Mediterranean horse mackerel, 5.86 to 13.55 microg/kg of body weight). An understanding of the factors leading to an increase in mercury exposure can help consumers make informed decisions about eating fish.     

Consumer neuroscience: an overview of an emerging discipline with implications for consumer policy

In recent years, interest in the integration and application of neuroscientific theories, concepts, findings and methods to the research discipline of consumer behavior has been increasing. The sub-discipline of consumer neuroscience that has resulted from that interest belongs to the innovative approach of neuroeconomics. Consumer neuroscience investigates problems of consumption and marketing through methods and findings from neuroscience. Conventional research in consumer behavior and marketing necessarily looked at the human organism as being a “black box??which cannot be assessed directly, or physiologically. This was a time when research mainly used theoretical constructs to interpret these bodily processes and resulting behavior. More recently, however, modern techniques and methods in neuroscience have facilitated a far more direct look into the “black box??of the organism as the basis for the sub-discipline of consumer neuroscience. Consumer neuroscience, therefore, can significantly benefit research in the field of consumer behavior, particularly in the attempt to better understand human behavior in decision-making processes. Although consumer neuroscience is a fledgling discipline, it constitutes a complementing advancement toward more comprehensive testing and expansion of theory. Against this background, the primary goal of the paper is to provide an overview of methods, findings, and implications of selected studies in consumer neuroscience. Furthermore, we integrate aspects of consumer policy and neuroethics, discussing the possible implications of these insights for consumer protection.     

Application of molecular identification tools for Lactobacillus, with a focus on discrimination between closely related species: A review

Lactobacillus is among the most important GRAS food lactic acid bacteria, with nearly 140 species at present, mostly of industrial importance. Being part of the natural flora of a range of food products like raw milk, fermented dairy products, fruits, vegetables, meat products they also serve as starters for a number of fermented food products either to enhance the quality or to add health benefits. These groups of economically important species are often alike in phenotypic and physiological characteristics, probably due to their co-evolution in the same ecological niches; hence they are difficult to be differentiated. This demands advanced methods for their proper identification and characterization. With the advancement of molecular biology, a range of DNA-based molecular techniques has replaced the largely cumbersome phenotypic methods. This review summarizes the various molecular techniques available for detection and identification within the genus Lactobacillus, with special emphasis on the four groups of closely resembling species: L. casei group, L. acidophilus group, L. delbrueckii subspecies, and L. plantarum group. This review also provides insights into current trends for alternative molecular markers other than 16S rRNA to resolve the ambiguity within phylogenetically close species in the genus Lactobacillus.     

A proposed standard procedure for taint tests with agricultural chemicals

Summary. This paper has been prepared under the auspices of the Advisory Committee on Taint of the Ministry of Agriculture, Fisheries and Food and is intended to meet the need for a standard procedure for taint tests with agricultural chemicals on processed foodstuffs of plant origin. the paper is divided into two main parts. the first section deals with trial design and site, chemical application, crops, sampling procedure, packing of raw materials, transport and storage of samples, processing and number of tests required to indicate whether a chemical substance may be accepted as being free from tainting characteristics. the second section deals with various aspects of the tasting tests, such as method employed, suitability and numbers of tasters, place and time of tasting and preparation of samples for tasting. the proposed method of tasting is the triangular test and details of calculating the results are given, together with appendices presenting the necessary tables and a worked example.     

Modelling consumer behavioural intentions towards food with implications for marketing quality low-input and organic food

The paper is based upon a study of European consumers’ behavioural intentions towards food purchase for four food products in six countries. The analytical method employs a structural equation model within the marketing framework of the quality-value-satisfaction-loyalty (QVSL) paradigm. The paper focuses on country-based versions of the model. The sample consists of 5072 regular consumers of the four products and includes consumers of conventional foods, quality low-input foods and organic foods. The model establishes the determinants of behavioural intentions towards foods that consumers purchase regularly. In addition, it provides the facility to examine the potential of quality low-input foods and organic foods. The results reveal the contribution of satisfaction, perceived value and perceived quality to improving behavioural intentions and how these constructs could contribute to the improved effectiveness of marketing conventional, quality low-input and organic foods to existing and potential consumers.