Determine Food Preferences Research Articles

Children’s physiological and behavioural response during the observation, olfaction, manipulation, and consumption of food products with varied textures. Part 2: Solid products

Texture is one of the main attributes that determine food preferences in schoolchildren. While texture acceptance and preference has been widely investigated in this target group, the effect of texture on other aspects of the food behaviour is still lacking. In this regard, one previous study evaluated the emotional response elicited by liquid textures showing that thicker liquids are less liked by schoolchildren and generally evoked a more negative emotional response. The current work was designed to extend the research conducted with liquid textures to solid food products. To achieve these goals, 45 children (5–12 yrs old) evaluated three solid products designed to only vary in texture following four sensory tasks: observation, olfaction, manipulation, and consumption. After each sample was tasted, children rated liking with a 7-pt hedonic scale. Facial expressions and Skin Conductance Response (SCR) were monitored during the test, and they were analysed as action units (AUs) and basic emotions as well as changes in SCR.Results showed that the three texture-modified solids tested were equivalently liked by the children. However, the products induced a significantly different emotional response at both unconscious and conscious level measured through automatic facial coding and SCR. The combined method used in this study showed good discrimination ability among the three samples tested, confirming that facial coding and SCR are suitable methods to measure the behavioural and physiological inherent of emotions in schoolchildren in a broad range of sensory tasks, such as the observation, olfaction, manipulation, and consumption of food samples.

Brain responses and connectivity to visual meal compositions: An EEG investigation into food liking

Understanding food liking, which shapes individual preferences for certain foods, is important for enhancing consumer satisfaction, encouraging healthier eating habits, and developing effective nutritional interventions. In this study, we aimed to investigate the neural underpinnings of food liking. We used electroencephalography (EEG) as a neuroscientific approach and visual food stimuli comprising various compositions of Korean meals. Our focus was to examine changes in brain responses and functional connectivity resulting from variations in visual meal compositions. The behavioral results showed that participants exhibited increased liking for meals with increased compositions. EEG source analysis demonstrated increased activity in the anterior insula, fusiform gyrus, precuneus, ventromedial prefrontal cortex, and medial orbitofrontal cortex (mOFC) and decreased activity in the dorsolateral prefrontal cortex (dlPFC) with increased meal liking. Furthermore, functional connectivity analysis revealed reduced connectivity between the dlPFC and both the mOFC and the anterior insula with increased meal liking. Notably, lower dlPFC-mOFC connectivity was associated with a greater preference for visual meal stimuli. Together, these results suggest that a decrease in neural communication between the brain regions responsible for subjective reward value processing and cognitive control, indicating a shift in attention towards the rewarding aspects of food, plays a significant role in food-liking decisions. Our study also emphasizes the integral role of various brain regions in determining food preference, thereby providing evidence for further neuroscientific investigations into dietary decision-making processes.

The effect of food shape on children’s implicit and explicit emotional response

The appearance of food products is one of the most important aspects that determine food preferences and food choices in children. One of the approaches suggested to prevent children’s rejection of food products is controlling the visual appearance attributes to enhance acceptability and a more positive emotional response. In this regard, the main objective of this study was to determine the influence of food shapes on the holistic emotional response of schoolchildren. A group of 50 children (5–12 years old) took part in individual sessions to observe and to consume two food products designed from apple juice to have the same sensory properties, except the shape (i.e., triangle vs. apple). To measure the emotional response holistically, an emoji-based questionnaire was used to capture children’s self-reported emotions, while facial expressions and the skin conductance response (SCR) were monitored to represent the behavioural and physiological responses. Results showed that there were no significant differences in acceptability when data were analysed on average, but 31% of the children were influenced by the food shape, the apple shape was more accepted than the triangle shape. On the other hand, the holistic emotional response elicited by both food products were significantly different. In this regard, the apple shape evoked a more positive emotional response compared to the triangle shape. The study of children’s preferences and emotional response towards food shapes may help the food industry and other researchers to develop new food products from a child-centric perspective, enhancing acceptability and a more positive emotional response in schoolchildren.

Nutritional and Lifestyle Factors Determining the Problem of Overweight and Obesity Among Teenagers and Youth During the COVID-19 Pandemic – A Comparative Survey Study Among Poles and Belarusians

Abstract Introduction: The prevalence of obesity is increasing worldwide, especially among youth. The main cause of obesity in young people is a combination of excessive caloric intake and reduced physical activity. In addition to individual dietary and physical activity behaviors, genetic predisposition, socioeconomic and environmental factors, and comorbidities may contribute to obesity. Aim: The study aims to examine and compare the factors determining food preferences and habits as well as the occurrence of overweight and obesity among teenagers and youth in Poland and Belarus. Material and methods: An anonymous questionnaire consisting of 58 questions based on the Eating Behavior Questionnaire (QEB) was used. Responses were received from 700 young people from Poland and 690 from Belarus, some of whom were rejected. The data was collected in May and June 2021 and analyzed in the Statistica program (statistically significant results at p<0.05). The research was financed by a grant from the Polish National Agency for Academic Exchange. Results: The study group was divided into four groups in terms of age and nationality: Poles <20 years old (428 people), Belarusians <20 years old (222 people), Poles 20-29 years old (210 people), and Belarusians 20-29 years old (295 people ). The correct BMI had 66.7%, 74.3%, 70.7%, and 71.2% of the respondents, respectively (p=0.057; p=0.888). In both age groups, in the Mann-Whitney U test, there are significant differences in the number of meals per day (p<0.001) - Poles eat 4 or 5 meals a day more often, and Belarusians 3. In the chi-square test, both age groups showed a significant statistical difference (p<0.001) in the question about eating breakfast every day - Poles eat breakfast more often than Belarusians. The Mann-Whitney U test showed no differences in sleep duration between the respondents from both countries (p=0.453; p=0.905). Conclusions: The results of the research indicate a strong need to implement educational programs to raise the awareness among young people about healthy eating. Obesity, skipping breakfast, too few meals during the day, and their incorrect composition indicate the direction of pro-health policy, which will be conducive to making the right food choices for youth.

Food Preference, Fecundity, Proximate Analysis on Eggs and Meat of <i>Turbo crassus</i> (W. Wood 1828) and <i>Turbo setosus</i> (Gmelin 1791) in Sepanjang Beach, Gunungkidul, Special Region of Yogyakarta

Turbo snails have important roles in the ecosystem as prey for predators, and decomposition of dead objects, and it is starting to decrease. This is quite worrying so that conservation efforts must be carried out immediately. Turbo snail species found in Sepanjang Beach, Gunungkidul are Turbo crassus and Turbo setosus. The aims of this study were to determine food preferences, the relationship between body size and fecundity, analyze egg quality based on proximate levels of the two species, and meat proximate of T. crassus and T. setosus. Samples were taken from Sepanjang Beach, Gunungkidul. Food preference was observed using the sedgwick rafter, fecundity was counted using the gravimetric method. Moisture content, protein content, fat content, ash, and carbohydrate content of both species eggs and meat were determined with proximate analysis at the UGM Central Laboratory for Food and Nutrition Studies. The results showed that the dominant food for T. setosus was Phaeophyta, whereas the dominant food for T. crassus was Microcoleus sp. and Phaeophyta. The fecundity of both Turbo species is exponentially positively correlated with all body sizes. Proximate analysis showed that the levels of fat and protein in the eggs of both species were quite high, which meant that the eggs are in good quality. The conclusion of this study is both species have slightly different food preferences. The fecundity of both species will increase exponentially with increasing body size and the broodstock of T. crassus and T. setosus Sepanjang Beach has good quality.

The Effect of the Musca domestica Salivary Gland Hypertrophy Virus on Food Consumption in Its Adult Host, the Common House Fly (Diptera: Muscidae).

The Musca domestica salivary gland hypertrophy virus (MdSGHV) substantially enlarges the house fly's salivary glands and prevents or delays ovarian development in its adult host, but the effect that MdSGHV has on the house fly's food consumption is currently unknown. Using house flies from a laboratory-reared colony, we evaluated the effect of MdSGHV infection on food consumption over a 7-d period. Both treatment (virus-infected) and control (saline-injected) flies were provided with a choice of 8% sucrose solution and 4% powdered milk solution to determine food preferences. Quantities of each solution consumed were measured every 24 h for each fly to measure food consumptions. Infected house flies were shown to consume less overall of both solutions than house flies injected with saline. The largest consumption discrepancy was seen between female house flies. Healthy female flies with developing ovaries continued to consume a sugar and protein diet, whereas infected female flies fed predominantly on a sugar diet. Additionally, infected male and female flies consumed significantly lower quantities of protein and sucrose than control flies. This suggests that MdSGHV has a negative consumption effect (e.g., hunger, starvation) on its host. Thus, differences in food consumption of infected and control flies probably represent differences in the nutritional requirements of flies resulting from viral infection.

Factors Associated with Sweet Taste Sensitivity in Patients with Type 2 Diabetes Mellitus (T2DM)

Introduction: Taste sensitivity plays a vital role in determining food preferences. Evidence suggests that patients with diabetes are less sensitive to sweet taste. Increased sugar consumption due to low sensitivity adversely affect the glycemic control in Type 2Diabetes Mellitus (T2DM). Although the factors associated with taste sen­sitivity have been assessed in healthy individuals, it is less reported in T2DM. Thus, the aim of this study was to determine the factors associated with taste sensitivity for sucrose in patients with T2DM.Method: A sample of 111 patients, aged between 35-60 years, having T2DM for > 5 years were considered. Baseline sociodemographic and anthropometric parameters were obtained. Supra-threshold intensity ratings for a range of sucrose concentrations were assessed using ‘general Labeled Magnitude Scale’. HbA1c was deter­mined at recruitment. Data was analyzed using Multiple Linear Regression.Results: Results showed that in patients with T2DM,a significant association was evident between the supra­threshold intensity ratings for the highest concentration of sucrose (2.02M) tested and the waist circumference (p=0.022), hip circumference (p=0.039) and waist-hip ratio (p=0.022). None of the other factors were signifi­cantly associated with either the highest or any other concentration tested.Conclusion: Reduction in waist circumference, hip circumference and waist hip ratio is likely to improve the sweet taste sensitivity in T2DM patients and vice versa. Maintaining these parameters within healthy limits may helpachieving a better glycemic profile through reducing the sugar consumption in patients with T2DM.

Trophic ecology of invasive marbled and spiny-cheek crayfish populations

North American cambarid crayfish have been highly successful in establishing and spreading across Europe and are now over-invading earlier arrivals in many water bodies. Parthenogenetic marbled crayfish (Procambarus virginalis), which originated from aquarium stocks, are relatively recent invaders and have established in lakes previously invaded by spiny-cheek crayfish (Faxonius limosus). However, the feeding ecology of marbled crayfish and consequential impacts on the non-native species’ coexistence are largely unexplored. By combining laboratory experiments with stable isotope analyses of field samples, we were able to (1) determine food preferences of both species under controlled conditions and (2) explore their trophic niches in three lakes where both species co-occur. In the food-choice laboratory experiments, the two species showed similar food preferences and consumption rates. Consistently, the stable isotope analyses (δ13C and δ15N) highlighted the intermediate trophic position of both species. Marbled crayfish and spiny-cheek crayfish occupied a wide range of trophic positions corresponding to a very generalist diet. However, marbled crayfish were more relying on arthropod prey than spiny-cheek crayfish which fed more on mollusks. This is the first work providing evidence for trophic plasticity of marbled crayfish in lake food webs. Our results suggest that the addition of marbled crayfish increases grazing pressure on macrophytes and macrophyte-dependent organisms and the allochthonous detritus decomposition in ecosystems already invaded by spiny-cheek crayfish. Since both species are listed as invasive alien species of EU concern, further assessments of potentially endangered food organisms are needed.

From Synapse to Supper: A Food Preference Recipe with Olfactory Synaptic Ingredients

C1ql3 protein and its receptor Bai3 are involved in synaptic organization and function. In this issue of Neuron, Wang etal. (2020) report that both are essential for synaptic function between the anterior olfactory nucleus and the olfactory bulb and for the generation, but not recall, of associative olfactory memories determining food preference in mice.

Effect of Pleurotus ostreatus powder addition in vegetable soup on ß-glucan content, sensory perception, and acceptability.

Pleurotus ostreatus is an edible mushroom with interesting nutritional properties, which is able to grow on agri‐food waste and could in turn be used as an ingredient for food fortification. However, new food products have to face with the growing consumer consciousness about what they eat and hedonic responses, which represent a key factor in determining food preference and choices. The aim of this study was to design a vegetable‐based product (a pumpkin and carrot soup) added with increasing concentration of P. ostreatus powder rich in β‐glucans, which are fibers with demonstrated bioactivity in humans, and to obtain a sensory description of these fortified products to find the desirable and undesirable sensory properties that affect their acceptance. A total of 109 subjects (women N = 52; men N = 57; age = 36.1 ± 14.4 years) evaluated five samples of pumpkin and carrot soup added with increasing concentrations of mushroom powder (0%, 2%, 4%, 6%, and a hidden control at 0%) for liking and sensory properties by means of the check‐all‐that‐apply method. Results showed that creaminess, orange color, mild odor, and taste were positively related to vegetable soups liking, whereas strong taste, dark color, and mushroom odor described the less liked samples. Sample added with 2% of mushroom powder obtained comparable liking scores to the unmodified sample, while liking decreased with increasing concentration of P. ostreatus powder. The present results demonstrated that it is possible to fortify a vegetable soup with P. ostreatus powder developing well‐accepted foods by consumers. This product could be used to implement an everyday dietary intervention of β‐glucans over a long‐term period.

Key physical wood properties in termite foraging decisions.

As eusocial and wood-dwelling insects, termites have been shown to use vibrations to assess their food, to eavesdrop on competitors and predators and to warn nest-mates. Bioassay choice experiments used to determine food preferences in animals often consider single factors only but foraging decisions can be influenced by multiple factors such as the quantity and quality of the food and the wood as a medium for communication. A statistical analysis framework is developed here to design a single bioassay experiment to study multifactorial foraging choice ( Pinus radiata) in the basal Australian termite species Coptotermes ( C.) acinaciformis (Isoptera: Rhinotermitidae). By employing a correlation analysis, 17 measured physical properties of 1417 Pinus radiata veneer discs were reduced to five key material properties: density, moisture absorption, early wood content, first resonance frequency and damping. By applying a fuzzy c-means clustering technique, these veneer discs were optimally paired for treatment and control trials to study food preference by termites based on these five key material properties. A multifactorial analysis of variance was compared to a permutation analysis of the results indicating for the first time that C. acinaciformis takes into account multiple factors when making foraging decisions. C. acinaciformis prefer denser wood with large early wood content, preferably humid and highly damped. Results presented here have practical implications for food choice experiments and for studies concerned with communication in termites as well as their ecology and coevolution with trees as their major food source.

Exotic Eucalyptus leaves are preferred over tougher native species but affect the growth and survival of shredders in an Atlantic Forest stream (Brazil).

We evaluated the effect of leaves of native and exotic tree species on the feeding activity and performance of the larvae of Triplectides gracilis, a typical caddisfly shredder in Atlantic Forest streams. Leaves of four native species that differ in chemistry and toughness (Hoffmannia dusenii, Miconia chartacea, Myrcia lineata and Styrax pohlii) and the exotic Eucalyptus globulus were used to determine food preferences and rates of consumption, production of fine particulate organic matter (FPOM), growth and survival of shredders. We hypothesized that the consumption rates of leaves of Eucalyptus and their effects on the growth and survival of shredders could be predicted by leaf chemistry and toughness. The larvae preferred to feed on soft leaves (H. dusenii and M. chartacea) independently of the content of nutrients (N and P) and secondary compounds (total phenolics). When such leaves were absent, they preferred E. globulus and did not consume the tough leaves (M. lineata and S. pohlii). In monodietary experiments, leaf consumption and FPOM production differed among the studied leaves, and the values observed for the E. globulus treatments were intermediate between the soft and tough leaves. The larvae that fed on H. dusenii and M. chartacea grew constantly over five weeks, while those that fed on E. globulus lost biomass. Larval survival was higher on leaves of H. dusenii, M. chartacea and S. pohlii than on E. globulus and M. lineata leaves. Although E. globulus was preferred over tougher leaves, long-term consumption of leaves of the exotic species may affect the abundance of T. gracilis in the studied stream. Additionally, our results suggest that leaf toughness can be a determining factor for the behavior of shredders where low-quality leaves are abundant, as in several tropical streams.

Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae).

The widespread African clawed frog (Xenopus laevis) occurs in sympatry with the IUCN Endangered Cape platanna (Xenopus gilli) throughout its entire range in the south-western Cape, South Africa. In order to investigate aspects of the interspecific competition between populations of X. laevis and X. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the Cape of Good Hope (CoGH) and Kleinmond. A total of 399 stomach contents of X. laevis (n = 183) and X. gilli (n = 216) were obtained together with samples of available prey to determine food preferences using the Electivity index (E*), the Simpson’s index of diversity (1 − D), the Shannon index (H′), and the Pianka index (Ojk). Xenopus gilli diet was more diverse than X. laevis, particularly in Kleimond where the Shannon index was nearly double. Both species were found to consume large amounts of tadpoles belonging to different amphibian species, including congeners, with an overall higher incidence of anurophagy than previously recorded. However, X. laevis also feeds on adult X. gilli, thus representing a direct threat for the latter. While trophic niche overlap was 0.5 for the CoGH, it was almost 1 in Kleinmond, suggesting both species utilise highly congruent trophic niches. Further, subdividing the dataset into three size classes revealed overlap to be higher in small frogs in both study sites. Our study underlines the importance of actively controlling X. laevis at sites with X. gilli in order to limit competition and predation, which is vital for conservation of the south-western Cape endemic.

Emotional responses to sweet foods according to sweet liker status

Sweetness is usually associated with positive affect, but it is known that there are systematic individual variations in the degree of pleasantness of sweet tastes. These variations are thought to be important in determining food preferences. The objectives of this study were to classify people according to sweet liker status, and to examine how they expressed emotions to foods varying in sweetness. The samples used in the study were four commercial products: two beverages (OD and MJ) and two biscuits (WB and CB), each pair differing in sweetness. Subjects were asked to rate their liking for the samples and any emotions elicited by them immediately after they consumed each of the products. Sweet likers (SL) and sweet dislikers (SD) were selected by hierarchical cluster analysis based on hedonic responses to the five concentrations of sucrose solution. SL expressed strong positive emotions in response to the CB and MJ, which were both highly sweet and highly liked by SL. However, they expressed relatively strong negative emotions to the far less sweet OD. In contrast, SD expressed relatively strong positive emotions to WB and MJ which were both liked, while they neither were positive about, nor liked, CB. This study clearly shows that emotional responses are subject to similar individual variations to sweet foods as are measures of liking. In turn, sweet liker status can be shown to be associated with varied emotional states elicited by foods varying in sweetness.

Salivary proteome and glucose levels are related with sweet taste sensitivity in young adults

ABSTRACTSweet taste plays a critical role in determining food preferences and choices. Similar to what happens for other oral sensations, individuals differ in their sensitivity for sweet taste and these inter-individual differences may be responsible for variations in food acceptance. Despite evidence that saliva plays a role in taste perception, this fluid has been mainly studied in the context of bitterness or astringency. We investigated the possible relationship between sweet taste sensitivity and salivary composition in subjects with different sucrose detection thresholds. Saliva collected from 159 young adults was evaluated for pH, total protein concentration and glucose. One- and bi-dimensional electrophoresis (2-DE) were performed and protein profiles compared between sweet sensitivity groups, with proteins that were differently expressed being identified by MALDI-FTICR-MS. Moreover, Western blotting was performed for salivary carbonic anhydrase VI (CA-VI) and cystatins and salivary amylase enzymatic activity was assessed in order to compare groups. Females with low sensitivity to sweet taste had higher salivary concentrations of glucose compared to those with sensitivity. For protein profiles, some differences were sex-dependent, with higher levels of α-amylase and CA-VI in low-sensitivity individuals and higher levels of cystatins in sensitive ones for both sexes. Body mass index was not observed to affect the association between salivary proteome and taste sensitivity. To our knowledge, these are the first data showing an association between sweet taste and saliva proteome.

Differences in food intake and genetic variability in taste receptors between Czech pregnant women with and without gestational diabetes mellitus.

Gestational diabetes mellitus (GDM) represents the most frequent metabolic disorder in pregnancy. Since dietary intake plays an important role in obesity and type 2 diabetes development, it is likely to be for the susceptibility to GDM too. Food preferences, driving partly the diet composition, are changing during pregnancy. Taste and genetic variability in taste receptors is an important factor in determining food preferences. Aims of our study were (1) to characterize dietary habits of pregnant women and to find possible differences in food preferences between healthy pregnant women and those with GDM and (2) to ascertain possible association of several single nucleotide polymorphisms (SNPs) in taste receptor (TR) genes with GDM. A total of 363 pregnant women (293 with GDM and 70 with physiologic pregnancy) were included in the study. Dietary pattern spanning the period of approx. 6months preceding the time of GDM screening was assessed using a semi-quantitative food frequency questionnaire. A total of five SNPs in TR genes were selected for genotyping based on their functionality or previous associations. Women with GDM exhibited significantly more frequent meat consumption (esp. poultry, pork and smoked meat), dairy products and sweet beverages consumption. The legumes consumption was found to be inversely correlated with fasting glycaemia (P=0.007, Spearman). CC genotype in TAS2R9 gene (SNP rs3741845) was significantly associated with GDM (P=0.0087, Chi-square test). Our study showed differences in dietary intake of selected food items between healthy pregnant women and those with GDM and genetic association of bitter taste receptor allele with GDM.

Diet composition and selection of the bighorn sheep (Ovis canadensis) in Sierra El Mechudo, Baja California Sur, Mexico

Water, food and nutrition are three of the main factors that regulate the distribution and abundance of wildlife species in a given area. In Baja California Sur, Mexico, the bighorn sheep is one of the most appreciated species for its ecological and economic value within the peninsular desert ecosystem; however, many aspects of its biology, ecology and population status remain unknown. The objective of the present study was to evaluate the diet composition of the bighorn sheep, analyzing the seasonal use and availability patterns of the plant species consumed. Using two food selection indices, we tested the hypothesis that the bighorn sheep opportunistically selects plant species from its habitat in the southern zone of Sierra El Mechudo, Baja California Sur, Mexico. The vegetation was characterized by means of 50 linear transects measuring 100 m x 5 m (500 m 2 ). The diet of the bighorn sheep was evaluated through the microhistological analysis of feces. We calculated the percentage of in-vitro dry-matter digestibility and the digestible energy of forage consumed by sheep. The similarity of seasonal vs. annual diet was determined through a cluster analysis. From two food selection indices (Ivlev’s electivity, Bonferroni), we estimated the proportion of use of plant species consumed by sheep to determine food preferences. In the habitat, we identified 21 families with 63 species in 2010 and 22 families with 50 species in 2011. Shrubs were the dominant forms. The analyses of faeces identified 47 species, consisting of 27 shrubs (62.1 %), 12 forbs (26.9 %), six trees (10.6 %), one succulent (0.2 %) and one unidentified species (0.1 %). The cluster analysis showed seven similar groups. Ivlev’s and Bonferroni indices showed the selection of Bourrieria sonorae , Melochia tomentosa and Caesalpinia placida by bighorn sheep in 2010; in 2011, it selected Bursera epinnata , Caesalpinia placida and Larrea tridentata . Non-significant differences between seasons were observed regarding the composition of plant species in the diet. Shrubs were the dominant life forms, followed by trees and succulents. Shrubs were the preferred food foraged by sheep, accounting for 62.1 % of the diet; this finding is consistent with values reported for Arizona and California. Non-significant differences were observed in the percent in-vitro dry matter digestibility and digestible energy of the plant species foraged by sheep. However, we found that sheep grazed preferentially on four plant species, three shrubs and one tree, of high food quality. In this study, the bighorn sheep behaved like a specialist; therefore, we rejected the hypothesis that this species forages opportunistically on plant species. Studies on the diet of the bighorn sheep are valuable to develop management plans for the species and its habitat, since these provide information to better understand the extent of vegetation use and whether distribution sites are suitable and meet with the requirements for the conservation of the species and its populations.

Behaviour directed towards inaccessible food predicts consumption—A novel way of assessing food preference

When determining an animal’s food preference based on comparative consumption, a major problem is the potential for individuals to over-eat, rendering subjects unavailable for subsequent tests as well as exposing them to potentially adverse health implications. Here, we explored alternative, simple and quick ways of assessing food preference that involved only minimal training and avoided satiation. In Study 1, we investigated whether behaviour directed towards inaccessible food predicted consummatory choice. Following a prime with small quantities of two types of food of putatively different quality, 18 pet dogs were concurrently presented with the same two food types in a manner that they could see and smell, but not physically access. Time spent investigating the two inaccessible food types was measured. Subsequently, the dogs were given the opportunity to consume the same two food types but this time in a restricted-intake consummatory test: two puzzle feeders were presented simultaneously, each containing 18 pieces of one of the two food types. The proportion of food types making up the first 18 pieces consumed was recorded. Subjects showed a highly significant preference for the food type predicted to be of higher value in both the non-consummatory and the consummatory test. Moreover the proportion of time spent investigating the two food types in the non-consummatory test was very similar to the proportion of the two food types consumed from the puzzle feeders, demonstrating validity of both test methods. There are, however, some limitations to the consummatory test, in particular that it can only be valid if the two food types to be compared are of similar ease to extract from the boards. To assess the generalizability of the non-consummatory food preference test, in Study 2 we investigated test-retest reliability in 20 dogs, as well as consistency of preferences across populations by comparing 20 owned pet dogs and 25 dogs housed in rescue shelters. Findings were consistent across repetitions of the test as well as across the two test populations. Thus, relative food preference could be confidently and reliably inferred from behaviour during a non-consummatory exposure. The ease and speed of use, the lack of training required and the avoidance of satiation make this an ideal test for determining food preference.

Molecular mechanisms of taste recognition: considerations about the role of saliva.

The gustatory system plays a critical role in determining food preferences and food intake, in addition to nutritive, energy and electrolyte balance. Fine tuning of the gustatory system is also crucial in this respect. The exact mechanisms that fine tune taste sensitivity are as of yet poorly defined, but it is clear that various effects of saliva on taste recognition are also involved. Specifically those metabolic polypeptides present in the saliva that were classically considered to be gut and appetite hormones (i.e., leptin, ghrelin, insulin, neuropeptide Y, peptide YY) were considered to play a pivotal role. Besides these, data clearly indicate the major role of several other salivary proteins, such as salivary carbonic anhydrase (gustin), proline-rich proteins, cystatins, alpha-amylases, histatins, salivary albumin and mucins. Other proteins like glucagon-like peptide-1, salivary immunoglobulin-A, zinc-α-2-glycoprotein, salivary lactoperoxidase, salivary prolactin-inducible protein and salivary molecular chaperone HSP70/HSPAs were also expected to play an important role. Furthermore, factors including salivary flow rate, buffer capacity and ionic composition of saliva should also be considered. In this paper, the current state of research related to the above and the overall emerging field of taste-related salivary research alongside basic principles of taste perception is reviewed.

Feeding properties of tench (Tinca tinca (Linnaeus, 1758)) in Hirfanlı Dam Lake (Kırşehir, Turkey)

Feeding biology of 249 tench (Tinca tinca) specimens varied between 0-VI years of age groups caught in Hirfanlı Dam Lake was investigated. The Geometric Index of Importance (GII) was used to determine food preferences of Tinca tinca. The monthly, seasonal and annual dependent preference of food of Tinca tinca were also investigated. Zooplanktonic (Copepoda, Rotifera, Cladocera, Ostracoda, Ephippium) and benthic (Chironomus, Oligochaeta, Gastropoda, Corethra, Gammarus) organisms along with extremities of these organisms, phytoplanktonic organisms (Bacillariophyta, Cyanophyta, Chlorophyta, Pyrrophyta, Euglenophyta), mud, detritus and fish eggs were determined in observed in the alimentary canal of fish. In this study algae were determined to be the most considerable food types which is followed by zooplanktonic and bentic organisms. 60 food items (44 organisms were plants and 16 were animals) were found in the alimentary canal of Tinca tinca. It was found the most feeding was occured in summer, fall, winter and spring, respectively. It was also found that the number of individuals with filled alimentary canal was higher in summer and fall months.