Fruit sensory evaluation

Esters are widespread in fruits and especially those with a relatively low molecular weight usually impart a characteristic fruity note to many foods, e.g. fermented beverages [49]. From the industrial viewpoint, esterases and lipases play an important role in synthetic chemistry, especially for stereoselective ester formations and kinetic resolutions of racemic alcohols [78]. These enzymes are very often easily available as cheap bulk reagents and usually remain active in organic reaction media. Therefore they are the preferred biocatalysts for the production of natural flavour esters, e.g. from short-chain aliphatic and terpenyl alcohols [7, 8], but also to provide enantiopure novel flavour and fragrance compounds for analytical and sensory evaluation purposes [12]. Enantioselectivity is an impor-... 

This paper is an attempt to document certain problems peculiar to sensory evaluation of citrus fruit or products primarily as they pertain to Florida and to perhaps offer some solutions or alternatives to these problems. 

Excessive pressure used in hand-reaming of citrus fruit can also result in juice containing high peel oil content and perhaps significant amounts of undesirable flavor constituents (primarily of a bitter nature) as well. Since high peel oil and undesirable flavor constituents would seriously affect sensory evaluation results in a negative way, care should be taken in hand-reaming citrus fruit to apply only as much pressure as necessary to extract most but not all of the juice. In this way the amounts of peel oil and undesirable flavor factors will be held to normal levels. 

Jellinek, G. Modern Scientific Sensory Methodology and Its Application to the Sensory Evaluation of Fruit Juices", International Federation of Fruit Juice Producers Meeting Madrid, Spain, 1967. 

In sensory evaluation consumers estimate fruit firmness on the basis of the deformation resulting from physical pressure applied by the hand and fingers. The toughness or tenderness of meat is subjectively evaluated in terms of the effort required for the teeth to penetrate and masticate the flesh tissues. Therefore, determination of rheological properties of foodstuffs is important in evaluation of consumer-determined quality by correlating rheological measurements with sensory tests. 

Sensory evaluations of the treated wine and fruit juice compared to the control were conducted. 9 of 10 judges identified correctly the treated Muscat wine and found a significant increase in the flavor and a richer Muscat flavor. 10 of 10 judges correctly identified the treated Apricot juice. In many cases, treated juice were prefered, in particular because of an intense fruitiness flavor. 

More cind more work is being done in correlating instrumental analysis with sensory evaluation. McCarthy et al (38) and Heinz et al (39) did earlier correlation studies on fruit. More recent works were done by Dupuy et al (40) amd Warner et al (41). They correlated sensory score vs G.C. euialysis on vegetable oils obtaining excellent results. 

C,H,60S, Mr 160.27 discovered and synthesized in 1976 as the typical flavor compound of the yellow passion fruit (Passiflora edulis) (see fruit flavors). Racemic cis-Zira/is-mixture 1 10, oil with an exotic fruity odor, bp. 85 -86 °C (1.6 kPa). Synthesis and sensory evaluation of the four stereoisomers demonstrated that the (-F)-(2S,4/f)-form was the compound with the typical passion fruit character, olfactory threshold in water 2 jmb, [alo" -f56.1 (CCI4). According to chiral analysis, however, the passion fruit contains the (4S)-epimer pair with an untypical, sulfurous, herby-green or, respectively flowery odor (-)-(2R,4S), [a]g -56.1 , and (-)-(2S,4S), (a]g -117.6°. For biosynthesis, see Ut.. ... 

The off-flavors due to the Maillard reaction are most typically labeled as being stale in character. Stale is one of the more nebulous terms used in sensory evaluation. Stale is a rather nondescript term denoting a lack of fresh character. Benzothiazole and 0-aminoacetophenone are two compounds believed to be formed via Maillard browning, which are responsible for this stale flavor. These compounds were found in stale, dry milk by Parks et al. [88]. 0-aminoacetophenone along with some furans were also found to be partially responsible for the gluey flavor of old casein [89]. There is also some work in this area related to fruit juices. 

Fruit juices and fruit-based flavorings should be kept chilled unless the soluble solids content exceeds 65°C Brix, or they should be suitably preserved. Samples should be made uniform and should be subjected to sensory evaluation before applying any of the physicochemical tests. 

In the case of pineapples, the 12 odorants listed in Table 16.7 were dissolved in water in concentrations equal to those determined in the fruit [50]. Then the odour profile of this aroma model was evaluated by a sensory panel in comparison to fresh pineapple juice. The result was a high agreement in the two odour profiles. Fresh, fruity and pineapple-like odour notes scored almost the same intensities in the model as in the juice. Only the sweet aroma note was more intense in the model than in the original sample [50]. In further experiments, the contributions of the six odorants showing the highest OAV (Table 16.7) were evaluated by means of omission tests [9]. The results presented in Table 16.8 show that the omission of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, ethyl 2-methylbutanoate or ethyl 2-methylpropanoate changed the odour so clearly that more than half of the assessors were able to perceive an odour difference between the reduced and the complete aroma model. Therefore, it was concluded that these compounds are the character-impact odorants of fresh pineapple juice. 

For many foods one of the most important quality criterion is freshness. This is especially so in numerous species of vegetables, fruits, and seafood. Fish of valuable species at the state of prime freshness, suitable to be eaten raw, may have a market price that is ten times higher than that of the same fish after several days of storage in ice but still very fit for human consumption. The characteristic freshness attributes of different foods are usually evaluated by sensory examination and by determination of specific indices, e.g., nucleotide degradation products in fish. 

Delarue, J. and Sieffermann, J.M. (2004). Sensory mapping using flash profile. Comparison with a conventional descriptive method for the evaluation of the flavor of fruit dairy products. Food Qual. Prefer., 15, 383-392. 

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