SURVIVAL ANALYSIS TO ESTIMATE SENSORY SHELF LIFE USING ACCEPTABILITY SCORES

ABSTRACT

In the present study, survival analysis was applied on consumers' acceptability scores, focusing the shelf‐life risk on the consumers disliking the product. Shelf life was estimated as the time necessary to reach a fixed percentage of consumers disliking the product, that is, the percentage of consumers scoring the product's overall acceptability below 6 in a 9‐point hedonic scale. In the present work, this methodology was applied to estimate the sensory shelf life of whole pan bread and alfajores. Shelf lives estimated considering 50% of the consumers disliking the product were shorter than those estimated considering consumers' rejection to consume. These results suggest that a proportion of consumers might dislike the sample but still answer “yes” when asked if they would consume the product at their homes. This could be attributed to the fact that when consumers are asked whether they would consume the product, they might think about consuming it after being stored at their homes. In this situation, consumers might be more tolerant toward sensory defects because they do not want to discard the product.

PRACTICAL APPLICATIONS

Sensory shelf life can be estimated using survival analysis considering the percentage of consumers disliking the product. This methodology seems to be a conservative criterion in order to assure the product's quality throughout its storage.     

Prediction of beef eating quality in France using the Meat Standards Australia system

An experiment was set up for (i) comparing Australian and French consumer preferences to beef and to (ii) quantify how well the Meat Standards Australia (MSA) grading model could predict the eating quality of beef in France. Six muscles from 18 Australian and 18 French cattle were tested as paired samples. In France, steaks were grilled ‘medium’ or ‘rare’, whereas in Australia ‘medium’ cooking was used. In total, 360 French consumers took part in the ‘medium’ cooking test, with each eating half Australian beef and half French beef and 180 French consumers tested the ‘rare’ beef. Consumers scored steaks for tenderness (tn), juiciness (ju), flavour liking (fl) and overall liking (ov). They also assigned a quality rating to each sample: ‘unsatisfactory’, ‘satisfactory everyday quality’ (3*), ‘better than everyday quality’ (4*) or ‘premium quality’ (5*). The prediction of the final ratings (3*, 4*, 5*) by the French consumers using the MSA-weighted eating quality score (0.3 tn + 0.1 ju + 0.3 fl + 0.3 ov) was over 70%, which is at least similar to the Australian experience. The boundaries between ‘unsatisfactory’, 3*, 4* and 5* were found to be ca. 38, 61 and 80, respectively. The differences between extreme classes are therefore slightly more important in France than in Australia. On average, even though it does not have predictive equations for bull meat, the mean predicted scores calculated by the MSA model deviated from observed values by a maximum of 5 points on a 0 to 100 scale except for the Australian oyster blade and the French topside, rump and outside (deviating by <15). Overall, the data indicate that it would be possible to manage a grading system in France as there is high agreement and consistency across consumers. The ‘rare’ and ‘medium’ results are also very similar, indicating that a common set of weightings and cut-offs can be employed.     

Untrained consumer assessment of the eating quality of beef: 1. A single composite score can predict beef quality grades

Quantifying consumer responses to beef across a broad range of demographics, nationalities and cooking methods is vitally important for any system evaluating beef eating quality. On the basis of previous work, it was expected that consumer scores would be highly accurate in determining quality grades for beef, thereby providing evidence that such a technique could be used to form the basis of and eating quality grading system for beef. Following the Australian MSA (Meat Standards Australia) testing protocols, over 19 000 consumers from Northern Ireland, Poland, Ireland, France and Australia tasted cooked beef samples, then allocated them to a quality grade; unsatisfactory, good-every-day, better-than-every-day and premium. The consumers also scored beef samples for tenderness, juiciness, flavour-liking and overall-liking. The beef was sourced from all countries involved in the study and cooked by four different cooking methods and to three different degrees of doneness, with each experimental group in the study consisting of a single cooking doneness within a cooking method for each country. For each experimental group, and for the data set as a whole, a linear discriminant function was calculated, using the four sensory scores which were used to predict the quality grade. This process was repeated using two conglomerate scores which are derived from weighting and combining the consumer sensory scores for tenderness, juiciness, flavour-liking and overall-liking, the original meat quality 4 score (oMQ4) (0.4, 0.1, 0.2, 0.3) and current meat quality 4 score (cMQ4) (0.3, 0.1, 0.3, 0.3). From the results of these analyses, the optimal weightings of the sensory scores to generate an ‘ideal meat quality 4 score (MQ4)’ for each country were calculated, and the MQ4 values that reflected the boundaries between the four quality grades were determined. The oMQ4 weightings were far more accurate in categorising European meat samples than the cMQ4 weightings, highlighting that tenderness is more important than flavour to the consumer when determining quality. The accuracy of the discriminant analysis to predict the consumer scored quality grades was similar across all consumer groups, 68%, and similar to previously reported values. These results demonstrate that this technique, as used in the MSA system, could be used to predict consumer assessment of beef eating quality and therefore to underpin a commercial eating quality guarantee for all European consumers.     

THE ROLE OF THE KNOWLEDGE OF COLOR AND BRAND NAME ON THE CONSUMER'S HEDONIC RATINGS OF TOMATO PUREES

The objective of study was to assess the influence of the knowledge of color and brand name on consumer response to tomato purees. From focus group interviews it was found that taste and odor of fresh tomato were the most important drivers of consumer choice. To quantify that information a questionnaire was developed and it was submitted to fifty consumers of tomato puree. The questionnaires answers confirmed those coming from the focus group, although same discrepancies were found with those derived from the consumer test. Results showed that color and brand name seemed to be more important than taste and odor of fresh tomato, in fact those attributes, when consumers were tasting samples, affected not only hedonic judgments but sensory perception as well. Finally physico-chemical parameters derived from instrumental measurements have been compared to sensory data by means of PCA in order to validate the consumers'assessment of sensory attributes of tomato puree.     

Optimal taxonomic groups for biodiversity assessment: a meta‐analytic approach

A fundamental decision in biodiversity assessment is the selection of one or more study taxa, a choice that is often made using qualitative criteria such as historical precedent, ease of detection, or available technical or taxonomic expertise. A more robust approach would involve selecting taxa based on the a priori expectation that they will provide the best possible information on unmeasured groups, but data to inform such hypotheses are often lacking. Using a global meta‐analysis, we quantified the proportion of variability that each of 12 taxonomic groups (at the Order level or above) explained in the richness or composition of other taxa. We then applied optimization to matrices of pairwise congruency to identify the best set of complementary surrogate groups. We found that no single taxon was an optimal surrogate for both the richness and composition of unmeasured taxa if we used simple methods to aggregate congruence data between studies. In contrast, statistical methods that accounted for well‐known drivers of cross‐taxon congruence (spatial extent, grain size, and latitude) lead to the prioritization of similar surrogates for both species richness and composition. Advanced statistical methods were also more effective at describing known ecological relationships between taxa than simple methods, and show that congruence is typically highest between taxonomically and functionally dissimilar taxa. Birds and vascular plants were most frequently selected by our algorithm as surrogates for other taxonomic groups, but the extent to which any one taxon was the ‘optimal’ choice of surrogate for other biodiversity was highly context‐dependent. In the absence of other information – such as in data‐poor areas of the globe, and under limited budgets for monitoring or assessment – ecologists can use our results to assess which taxa are most likely to reflect the distribution of the richness or composition of ‘total’ biodiversity.     

SENSORY EVALUATION OF VANILLA-DAIRY DESSERTS BY REPERTORY GRID METHOD AND FREE CHOICE PROFILE

“Natillas” are semisolid dairy desserts widely consumed in Spain, with notable differences existing between commercial brands in their composition and sensory and physical properties. The repertory grid method, in conjunction with the free choice profile (FCP), was used to provide data on how consumers perceived eight commercial “natillas” samples. The most frequent terms used were: vanilla flavor, sweetness, consistency and liquid texture as described by 77, 67, 57 and 53% of the consumers, respectively. A three‐dimensional solution was chosen. Dimension 1 accounted for 27.23% of variance and separated the samples largely by yellow‐color intensity and consistency. Dimension 2 (15.88%) was mainly related to the visual attributes of texture, creaminess and different notes of flavor. The third dimension (11.34%) was related to structural‐texture attributes, orange‐yellow color and acid and artificial flavors. The assessors plot showed two clusters. Analysis of each group data revealed differences in their perception of sample variation, mainly regarding texture and color.     

Avoidance and suppression of plant defenses by herbivores and pathogens

Plants are nutritious and hence herbivores and phytopathogens have specialized to attack and consume them. In turn, plants have evolved adaptations to detect and withstand these attacks. Such adaptations we call ‘defenses’ and they can operate either directly between the plant and the plant consumer or indirectly i.e. when taking effect via other organisms such as predators and parasitoids of herbivores. Plant defenses put selection pressure on plant-consumers and, as a result, herbivores and pathogens have evolved counter-adaptations to avoid, resist, or manipulate plant defenses. Here we review how plant consumers have adapted to cope with plant defenses and we will put special emphasis on the phenomenon of suppression of plant defenses.     

SOME UNRESOLVED ISSUES OF CONTROL IN CONSUMER TESTS: THE EFFECTS OF EXPECTED MONETARY REWARD AND HUNGER

Consumer test subjects were split into four groups: (1) Rewarded — told they would receive payment; (2) Unrewarded — told they would not receive payment; (3) Hungry — told not to eat before the test; and (4) Pre-fed — told to eat a meal before the test. Hedonic responses for four breaded fish samples were collected. The test design was then repeated using microwave popcorn as stimuli. Rewarded subjects and hungry subjects rated samples higher than did either the unrewarded subjects or the pre-fed subjects. The responses of both the rewarded and the hungry subjects indicated no hedonic differences between samples; but among the unrewarded and the pre-fed subjects, significant differences between samples were found. Results present a dilemma for those experimenters using acceptance ratings by consumers to guide product development. This paper discusses the issue of whether these, and other unresolved factors, need to be controlled when conducting consumer tests.     

CONSUMERS REPORT PREFERENCES WHEN THEY SHOULD NOT: A CROSS-CULTURAL STUDY

If a chi‐squared analysis were to be performed to determine whether preferences were significant in a paired preference test, the appropriate expected frequencies in the analysis would represent those that would occur should the consumers have no preference. One way of determining these ‘no preference’frequencies, for a particular test situation, would be to note the preference responses obtained when the stimuli were putatively identical. Over 2000 consumers were given paired preference tests in which the stimuli were putatively identical. Response conditions and consumer groups were varied and the proportions of preference and no preference responses were noted. In a preliminary experiment, further research was seen to be justified when for putatively identical stimuli, judges did not exclusively express lack of preference; many expressed a preference for one or other of the stimuli. Further experiments were conducted using a written response condition and putatively identical potato chips (potato crisps) as stimuli. Using a single ‘no preference’option, variation in the placement of this option at either first, second or third place on the response sheet had no significant effect on the response frequencies. The proportion of ‘no preference’responses was approximately 30% in all cases. A previously reported 40‐20‐40 distribution was not always confirmed. The experiment was repeated with Korean consumers; these had fewer ‘no preference’responses. Deriving preferences from hedonic scales, rather than having judges respond to preference options, increased the proportion of ‘no preference’responses, with American judges still having more than Korean judges. Yet there are logical objections to extracting preference data from hedonic scales. Increasing the number of ‘no preference’options to two or three, had the effect of increasing the number of ‘no preference’responses up to as much as approximately 60%. Extending the results to Koreans, using two ‘no preference’options, it was seen that only the judges in an anonymous response condition had significantly fewer ‘no preference’responses than Americans. The use of these response frequencies as expected frequencies in chi squared analyses was illustrated, after adjustments for counterbalancing.     

Are all GMOs the same? Consumer acceptance of cisgenic rice in India

India has more than 215 million food‐insecure people, many of whom are farmers. Genetically modified (GM) crops have the potential to alleviate this problem by increasing food supplies and strengthening farmer livelihoods. For this to occur, two factors are critical: (i) a change in the regulatory status of GM crops, and (ii) consumer acceptance of GM foods. There are generally two classifications of GM crops based on how they are bred: cisgenically bred, containing only DNA sequences from sexually compatible organisms; and transgenically bred, including DNA sequences from sexually incompatible organisms. Consumers may view cisgenic foods as more natural than those produced via transgenesis, thus influencing consumer acceptance. This premise was the catalyst for our study—would Indian consumers accept cisgenically bred rice and if so, how would they value cisgenics compared to conventionally bred rice, GM‐labelled rice and ‘no fungicide’ rice? In this willingness‐to‐pay study, respondents did not view cisgenic and GM rice differently. However, participants were willing‐to‐pay a premium for any aforementioned rice with a ‘no fungicide’ attribute, which cisgenics and GM could provide. Although not significantly different (P = 0.16), 76% and 73% of respondents stated a willingness‐to‐consume GM and cisgenic foods, respectively.     

THE ‘WARRIOR GENE’ AND THE MÃORI PEOPLE: THE RESPONSIBILITY OF THE GENETICISTS

The ‘gene of’ is a teleosemantic expression that conveys a simplistic and linear relationship between a gene and a phenotype. Throughout the 20th century, geneticists studied these genes of traits. The studies were often polemical when they concerned human traits: the ‘crime gene’, ‘poverty gene’, ‘IQ gene’, ‘gay gene’ or ‘gene of alcoholism’. Quite recently, a controversy occurred in 2006 in New Zealand that started with the claim that a ‘warrior gene’ exists in the Mãori community. This claim came from a geneticist working on the MAOA gene. This article is interested in the responsibility of that researcher regarding the origin of the controversy. Several errors were made: overestimation of results, abusive use of the ‘gene of’ kind of expression, poor communication with the media and a lack of scientific culture. The issues of the debate were not taken into account sufficiently, either from the political, social, ethical or even the genetic points of view. After more than 100 years of debates around ‘genes of’ all kinds (here, the ‘warrior gene’), geneticists may not hide themselves behind the media when a controversy occurs. Responsibilities have to be assumed.     

CONSUMER ACCEPTABILITY OF VEGETABLE SOUPS

The aim of this study was to investigate whether product label information “produced with organic ingredients” and “stabilization technology” affects consumer acceptability of vegetable soups. Three focus group interviews were preliminarily conducted in order to gain information about the appropriate terminology to use in the next consumer test. In all, 109 subjects were recruited by means of a background questionnaire. They were then divided into three groups according to age, gender and soup preference. Each group evaluated three different types of soup in two phases, first blind and then with information. At the end of the second phase, the participants filled in a conjoint analysis questionnaire. The results demonstrated that if consumers were informed that soup is prepared with organic ingredients, they would improve their acceptability scores, whatever the soup type. Stabilization technology information had no effect. Conjoint results revealed that consumers appreciate soups made with organic legumes and cereals and without seasoning. However, differences among subgroups were found.     

WINTER ROOSTING AND FEEDING BEHAVIOUR OF PIED WAGTAILS MOTACZLLA ALBA NEAR OXFORD, ENGLAND

This study presents data on the roosting and feeding behaviour of Pied Wagtails around Oxford, England. During the winter of 1977–78, from two to 1200 wagtails roosted in a Phragmites reed-bed. Use of this roost was greatest during mild, windless weather and the birds apparently used alternate roosts during harsh weather. Movement between roosts sometimes occurred between sunset and sunrise. Morning ‘departure group’ size, number leaving per unit time and diversity of departure directions increased with roost size. Wagtails quickly left the vicinity in the morning. In the afternoon, they joined one or more pre-roost gatherings before entering the roost for the night. Behaviour upon arrival at the roost was variable: birds might enter the reeds quickly or circle in large groups before landing. Aerial revolutions and generally ‘restless’ behaviour often accompanied increases in roost size. Wagtail feeding rates varied significantly between and within habitats. Number of wagtails feeding on the flooded Port Meadow, located 2–3 km south of the main roost, varied from about five to over 60 on different days; these numbers were not correlated with feeding rates. In contrast, the number of birds feeding at a sewage farm was nearly constant all winter. Some wagtails show high fidelity to feeding areas but others do not. Five short-term food supplementation experiments indicated that wagtails knowledgeable about a dense food source are not followed in the morning by naive birds. Results of this study are discussed in relation to the predation, physiology and information centre hypotheses that have been suggested to explain communal roosting in birds. I conclude that the communal roosting system of Pied Wagtails has physiological and anti-predator functions. Wagtails appear to choose certain roosts because of the protection that they provide from adverse climate and predation.     

Meat eating in wild hamadryas baboons: Opportunistic trade‐offs between insects and vertebrates

The consumption of meat may provide herbivorous animals with important nutrients that are scarce in their plant‐based diet. Seasonal variation in plant food availability has been suggested to motivate dietary flexibility in a range of species and thus primates may seek more prey when key plant resources are unavailable. Alternatively, prey encounter rate may drive meat eating. Here we investigate patterns of meat eating in hamadryas baboons (Papio hamadryas) at Filoha, Awash National Park, Ethiopia. The Filoha baboons rely largely on doum palm fruit (Hyphaene thebaica), which are available most months of the year, and the young leaves of Acacia senegal, which are more abundant during the wet season. We hypothesized that the baboons would consume more meat when H. thebaica and A. senegal were less available, which we tested by comparing meat eating and consumption of these plant food species from March 2005 through February 2006. Our results reveal a high rate of vertebrate meat eating at Filoha (0.028/hour of observation) compared with other hamadryas sites. We found no relationship, however, between meat eating (either insect or vertebrate) and either rainfall or consumption of H. thebaica or A. senegal, indicating that availability of preferred plant resources does not drive meat consumption. Vertebrate consumption and time spent feeding were significantly negatively associated; there was no relationship, however, between the consumption of animal matter and either home range size or daily path length. Vertebrate and insect consumption alternated throughout the year such that the baboons maintained a small amount of animal matter in their diet year‐round. Our results suggest that the baboons do not often actively seek animal matter, but consume it opportunistically, with the presence of locust and dragonfly swarms driving insect consumption, and both prey availability and the availability of feeding time shaping vertebrate predation.     

THE DESTRUCTION OF XYLEM BY A PLASMODIAL PARASITE IN SEEDLINGS OF PISUM SATIVUM

The seedlings of Pisum sativum var. ‘Alaska’ grown either in complete darkness or in partial red light are often afflicted by a plasmodial parasite, which either partially or completely destroys the tracheids. The vegetative stage of the organism consists of small cells connected with each other by hyaline filaments. These cells are seen inside the tracheids, where they presumably hydrolyze cellulose to separate the lignified helical wall thickenings from the cell wall. The spirals are then incorporated into a plasmodium. The plasmodia are found both inside and outside the plant tissue. The younger portions of the seedlings often contain large plasmodia with engulfed helical wall thickenings, which are gradually dissolved, presumably by means of a peetinolytic enzyme, at the time of sporulation. The spores (4–5μ) are borne in small numbers, ca. 10–16 per well-defined oval or elongate sporangium. The pitted vessels are not destroyed by the organism. Pea seedlings can be badly infected without showing externally visible pathology. Unless the xylem is destroyed and the plant tissues are filled with plasmodia, recovery from the infection is possible. Pisum sativum, a homozygous variety ‘L’ grown aseptically in light on an agar medium, also contained all the stages in the development of this organism.     

Are kubo hunters ‘show offs’?

The ‘show off’ hypothesis proposed by K. Hawkes, and tested using data on Ache foragers, makes important connections between food resource choice, reproductive strategies, and food sharing by human foragers. We test predictions derived from that hypothesis concerning contexts of meat acquisition, association between individuals, mobility, and reproductive success among Kubo hunter-horticulturalists of the interior lowlands of Papua New Guinea. Application of the hypothesis to both the Kubo and Ache cases is questioned. Differences between Kubo males in means and variances of returns from hunting arise as a consequence of differential target specialization; they do not map onto variation in reproductive success.