Odour profiling of apple cultivars and correlation with volatile compounds

We are using a trained sensory panel to define the sensory attributes profile of a wide number of apple commercial cultivars and new selections under evaluation at FEM (Fondazione Edmund Mach). The same fruit are evaluated through instrumental determinations as well. Here we present the correlations found between perceived odours (by trained panel) and volatile compounds (by SPME‐GC‐MS) in 18 apple cultivars. It is known that perceived odours are mainly the result of mixture of odorants (more than 300 compounds that can contribute to apple odour and flavour have been identified) and the single components of a mixture may lose their individual identity and a new mixture with a specific odour quality could emerge. Thus the correlations between odours and volatile compounds in apples were investigated by a multivariate approach. Regression models allowed the identification of compounds highly contributing to the odours arising from the complex mixture of volatile compounds released by apples. For example acetate esters strongly contribute to different fruity attributes and the results suggest that perceived odours are due to the relative proportions among esters rather than their presence/absence. In conclusion, sensory and instrumental profiling in combination with appropriate chemometric analyses can help to elucidate the relationships between the perceived odours in real food and the complex mixture of released volatile compounds

Effects of sensory characteristics and health information on acceptability of apples

Recent studies incorporating product tasting in a conjoint framework have shown that sensory aspects have a primary influence on product liking whereas extrinsic factors may have a secondary role (1). Nevertheless there are, to the authors’ knowledge, no conjoint studies based on measuring the effects of different levels of sensory characteristics in fruit and vegetable. Aim of this work is to study whether the varying of different levels of intrinsic sensory attributes (crunchiness and sweetness) and of the information about fibres and antioxidants content (extrinsic) given just before tasting can influence the acceptability of apples. A fractional factorial design was applied to evaluate the influence of intrinsic factors and extrinsic factors on the liking of 8 products. Four apple cultivars with 2 levels of crunchiness and sweetness were selected on the basis of the quantitative descriptive analysis of 21 varieties under study in a larger project supported by the Autonomous Province of Trento, Italy (AP 2010/2011). Then, 221 consumers were asked to evaluate the global liking of the 4 cultivars which were presented twice and were accompanied with different information about their contents in fibres and antioxidants. A preliminary blind test was also performed in order to measure their acceptability without any information. Additional data regarding consumer opinions, knowledge about healthy aspects, fruit consumptions and demographic data were also recorded. Significant effects were found for sensory factors while the extrinsic factors did non affect the consumers’ preference. In particular, global liking is positively influenced by high levels of crunchiness and sweetness. This confirms the importance of sensory characteristics in consumer acceptability, whereas it suggests that information about the amount of healthy components are of far less relevance at least for population average. This may not be the case for products that are not widely considered as healthy as apple

Sensory profiling of apple cultivars

Sensory quality of apples, recognised as a key factor driving consumer choice, is frequently indirectly measured using basic instrumental or pomological descriptors. Several studies so far investigated the correlations between instrumental measurements and sensory properties, these latter not always analysed by trained panel according to proper sensory science principles. Here, we present the setting up and the application of a trained panel sensory evaluation tool for the characterization of apple. Fruit physical and chemical parameters related to sensory descriptors of flavour and texture (basic composition, volatile metabolite profiling and texture profiling) were instrumentally measured as well. The proposed methodology, validated on a wide selection of apple cultivars (more than 20 commercial varieties and 11 new FEM accessions) over 2 years of production, allows to discriminate among different cultivars and highlights the perceivable changes developed during postharvest. Multivariate regression models show that it is possible to predict by instrumental measurements most of the textural sensory properties together with some flavour attributes. The opportunity to monitor several important sensory attributes makes the proposed sensory/instrumental approach a valuable tool for cultivar evaluation in breeding programs to assist the genetic improvement of new apple accession characterised by a better fruit quality, oriented towards the consumer preferences

Odour profiling of apple cultivars and correlation with volatile compounds

We are using a trained sensory panel to define the sensory attributes profile of a wide number of apple commercial cultivars and new selections under evaluation at FEM (Fondazione Edmund Mach). The same fruit are evaluated through instrumental determinations as well. Here we present the correlations found between perceived odours (by trained panel) and volatile compounds (by SPME‐GC‐MS) in 18 apple cultivars. It is known that perceived odours are mainly the result of mixture of odorants (more than 300 compounds that can contribute to apple odour and flavour have been identified) and the single components of a mixture may lose their individual identity and a new mixture with a specific odour quality could emerge. Thus the correlations between odours and volatile compounds in apples were investigated by a multivariate approach. Regression models allowed the identification of compounds highly contributing to the odours arising from the complex mixture of volatile compounds released by apples. For example acetate esters strongly contribute to different fruity attributes and the results suggest that perceived odours are due to the relative proportions among esters rather than their presence/absence. In conclusion, sensory and instrumental profiling in combination with appropriate chemometric analyses can help to elucidate the relationships between the perceived odours in real food and the complex mixture of released volatile compounds

L'interazione multisensoriale nella percezione della texture della mela

Il ruolo del suono è determinante per l’accettabilità di alcune categorie di alimenti secchi e di prodotti vegetali ad elevato contenuto d’acqua. Zampini e Spence (2004), ad esempio, hanno dimostrato che la percezione della croccantezza e freschezza delle patatine è modulabile modificando il suono prodotto durante la masticazione. In questo studio l’attenzione si è focalizzata sulle mele e su come la percezione di parametri di texture correlati o meno al suono (croccantezza e durezza) possa essere influenzata dal suono prodotto al primo morso. In un primo test sono state scelte tre varietà di mela con profili di texture distinti (Renetta, Golden e Fuji). I partecipanti, indossando delle cuffie, mordevano i campioni di mela con gli incisivi stando vicini ad un microfono. Le alte frequenze del suono prodotto dal morso (2-20kHz) potevano essere ridotte (-12dB e -24dB) o lasciate invariate (0dB). I risultati indicano che l’intensità della croccantezza decresce in maniera significativa in tutte e 3 le tipologie di mela con le due attenuazione del suono. Le condizioni sono state replicate in un secondo test limitandosi però alle due varietà di mela con valori di texture più estremi e introducendo la condizione di suono non amplificato (microfono spento) accanto ai livelli di attenuazione 0dB e -24dB già testati. I partecipanti valutavano oltre alla croccantezza anche la durezza. I risultati confermano la modulazione della percezione della croccantezza e indicano un interessante effetto del suono sulla durezza, un parametro non acustico valutato attraverso meccano-recettori: nel test la sua intensità si riduce infatti quando il microfono è spento rispetto a quando il suono non è manipolato. Questa ricerca conferma il ruolo del suono nella percezione della croccantezza anche in cibi ad elevato contenuto d’acqua e dimostra, per la prima volta, l’influenza del suono nella valutazione di parametri non acustici (durezza), offrendo nuovi spunti allo studio sensoriale della mela

Multisensory modulation of texture perception in apples

Crispness is an important texture parameter influencing sensory evaluation of food, as it works as a predictor of overall food quality. Previous research demonstrated that crispness perception of dry foods could be modulated by the sound the perceiver produced while biting into them (1). Therefore, we investigated whether multisensory effects on crispness perception could be extended to wet food (apples). Additionally, we were interested in verifying whether sound could also modulate perceived hardness, given that hardness (unlike crispness; 2) is considered to mainly rely on mechanical cues. Participants here were asked to bite a series of apple cylinders and to rate their crispness or hardness using a rating scale. Crucially, they heard their biting sound (either realistic or manipulated) through headphones. Measures have been replicated with different apple varieties with the aim to study the sound manipulation effect at different intensity levels for crispness and hardness. In experiment 1, participants evaluated the perceived crispness of cylinders from 3 apple varieties differing in crispness (‘Reinette’-low, ‘Golden’-medium, and ‘Fuji’-high). High frequencies of sound (2-20 kHz) were reduced (-12 dB or -24 dB) or were left unmodified (realistic sound). The results confirmed the role of sound manipulation in crispness perception also in the case of wet food: Apples were perceived as being less crispy when both sound reductions were applied than with the realistic sound. Additionally, apple varieties were correctly perceived as differing in terms of crispness (‘Reinette’<‘Golden’<‘Fuji’). In experiment 2, participants evaluated the perceived crispness and hardness of cylinders obtained from apples differing both in crispness and in hardness (‘Reinette’-low vs. ‘Fuji’-high). Sound manipulation consisted in presenting the realistic sound, or in reducing high frequencies of -24 dB, or else in switching the microphone off (thus dampening the acoustic cues overall). The results for both crispness and hardness confirmed that apples were rated significantly different (‘Fuji’ was perceived as the hardest and most crispy). As for sound, any reduction (-24 dB or microphone off) in the auditory information lowered the perceived crispness of apples as compared to the realistic sound. Interestingly, apples were perceived as being less hard when the microphone was switched off than when the real sound was presented. This supports the existence of multisensory effects of sound also for mechanical texture parameters. In experiment 3, participants underwent the same conditions as in experiment 2 with the sole difference of white noise being continuously presented through the headphones. The volume was such as to try and cover any sounds coming from outside the headphones. The results replicated those obtained in experiment 2 as to the effects of apples both for crispness and for hardness. The effect of sound, though, disappeared for crispness, while it was marginal for hardness (with apples judged as being softer only with the microphone switched off). This research effectively extends to wet foods the study of sound effects on perceived crispness. Additionally, it demonstrates for the first time that such multisensory effects can be highlighted in evaluations considered as being mainly guided by mechanical cues. REFERENCES (1) Zampini, M., & Spence, C. (2004). The role of auditory cues in modulating the perceived crispness and staleness of potato chips. Journal of Sensory Studies, 19, 347-363. (2) Christensen, C. M., Vickers, Z. M. (1981). Relationships between chewing sounds to judgments of food crispness. Journal of Food Science, 46, 574-578

A combined sensory-instrumental approach for apple texture profiling

Apple texture attributes, as crunchiness and juiciness, are important quality features which affect consumer’s appreciation [1]. Although previous studies proved the usefulness of instrumental characterization of textural properties, sensory analysis can directly measure physico-mechanical differences which are perceived by consumers. In this work we implemented and applied to 21 apple cultivars the combination of sensory and instrumental techniques in order to provide an effective characterization of their texture. The cultivars, selected from a large collection at Fondazione Edmund Mach, well represent the expected variability on the basis of a previous phenotyping [2]. Sensory profiling was provided by a trained panel, which developed a consensus vocabulary including 7 texture (firmness, crispness, juiciness, crunchiness, flouriness, mealiness, fibrousness), 2 visual and 6 odour/flavour attributes. On the same samples, mechanical and acoustic response under flesh compression have been simultaneously recorded (TA-XT texture analyzer equipped with an Acoustic Envelop Detector). This instrumental characterization has shown to be a promising strategy for dissecting the fruit texture variability [2]. Both sensory and instrumental profiles were effective in describing and discriminating the apple cultivars. PLS regression between sensory and instrumental data provided models with good predictive performances: cross-validated R2 > 0.81, for all attributes with the exception of juiciness (0.71). This indicates that juiciness perception is modulated also by chemical stimuli that are not accounted for in our instrumental textural data. Calibration models considering both mechanical/acoustic data and chemical composition data are under study. Our results, from a large cultivar selection, show that it is possible to quantify some important perceived apple characteristics related to texture by sensory methods and that our rapid instrumental approach can predict some important textural attribute. We propose it as a valuable tool for cultivar evaluation in breeding programs and possibly also for quality control

Application of fundamental principles of sensory analysis to support the quality control of PDO products based on expert panel evaluations

A quality control based on sensory analysis is particularly important in the case of PDO products because the perceived quality is one of the key elements to support competitiveness and profitability. In this study, we consider Trentingrana cheese, a variety of the PDO Grana Padano, exclusively produced in a restricted mountain region in northern Italy, where it represents the most important dairy product. Since 11 years, the Trentingrana Consortium supervises the production of cooperative dairies in two phases: Firstly, official inspectors classify cheese wheels on-site as “first quality”, “second quality” or “discarded” and, secondly, “first quality” wheels are sampled every 2 months within each dairy and assessed by a panel of experts for 7 sensory attributes. Based on the results of the assessment, dairies receive a price premium or penalty depending on a quality index, which is the weighted average of the scores assigned to each sensory attributes for the sampled wheel [1]. In the frame of the research project “Quality aspects of Trentingrana production chain” supported by Autonomous Province of Trento (Italy), we improved the Consortium procedure by implementing its scientific sensory approach. The data set collected over 8 years and the evaluation procedures applied by the Consortium were critically analyzed: A few critical points were then highlighted and the corresponding solutions were suggested (e.g., the application of a real experimental design, the definition of sensory specifications for attributes, the implementation of a systematic judges’ training and performance check). Here, we describe the improvement obtained by the implementation of some proposed changes to demonstrate how the applications of fundamental principles of sensory analysis improved the quality control system. With this work, we would like to provide methodological hints for the proper implementation of sensory analysis for the quality control in productive context

Thinning via shading: the sensory quality of apples grown by a new technique

Managing the orchard light microclimate is an emerging technology to improve high quality fruit production. Sensory analysis was used to evaluate eating quality of apples from trees either thinned by photosynthetic inhibition or grown under photoselective hail nets. Apples were evaluated by a trained panel (10 judges) according to quantitative descriptive analysis for 13 attributes (2 for odour and flavour, 2 for external appearance, 6 for texture, and 3 for taste properties). The same fruit were subjected to instrumental measurements by a TA-XT texture analyzer, to measure mechanical and acoustic response during a compression test: Furthermore cell anatomical features were studied by microscopy. Rosy Glow trees were thinned by 90% neutral shading cloth applied 30 days after full bloom for one week, and fruit were compared with fruit from chemically thinned trees. The efficacy of shading is comparable with the chemical thinner, although the costs are not comparable yet. Fuji apples were sourced from sectors of an orchard covered with photoselective hail nets: black (control), white, red, yellow, blue. Rosy Glow apples showed no sensory, instrumental or histological differences between chemical or shade-thinning: although shading is applied later than chemical thinning (i.e. further down the cell division stage), this did not have an impact. In Fuji, the panel did not perceive any difference among the coloured nets. Nevertheless, small but significant differences were found in mechanical and acoustic properties of these fruit, related to cell packing. Variations in spectral light composition may cause different cell division and expansion rates in the fruit, which could affect texture characteristics. These preliminary results confirm light management in the orchard as promising to improve quality and reduce chemical use in apple production