The electronic nose (e-nose) is designed to crudely mimic the mammalian nose in that most contain sensors that non-selectively interact with odor molecules to produce some sort of signal that is then sent to a computer that uses multivariate statistics to determine patterns in the data. This pattern recognition is used to determine that one sample is similar or different from another based on headspace volatiles. There are different types of e-nose sensors including organic polymers, metal oxides, quartz crystal microbalance and even gas-chromatography (GC) or combined with mass spectroscopy (MS) can be used in a non-selective manner using chemical mass or patterns from a short GC column as an e-nose or “Z” nose. The electronic tongue reacts similarly to non-volatile compounds in a liquid. This review will concentrate on applications of e-nose and e-tongue technology for edible products and pharmaceutical uses.

Huanglongbing (HLB) or citrus greening disease is the most severe citrus disease, devastating the industry worldwide. The presumed causal bacterial agent Candidatus Liberibacter spp. affects tree health as well as fruit development, ripening and quality of citrus fruit and juice. Fruit from infected trees can be either symptomatic or asymptomatic. Symptomatic fruit are small, asymmetrical and greener than healthy fruit. Furthermore, symptomatic fruit show higher titratable acidity and lower soluble solids, solids/acids ratio, total sugars and malic acid levels, lower ethyl butanoate, valencene, decanal and other ethyl esters, straight-chain aldehydes and sesquiterpenes, but higher in many monoterpenes compared to healthy and asymptomatic fruit. The disease also causes an increase in secondary metabolites in the orange peel and pulp, including hydroxycinnamic acids, limonin, nomilin, narirutin and hesperidin. Resulting from these chemical changes, juice made from symptomatic fruit is described as distinctly bitter, sour, salty/umami, metallic, musty, and lacking in sweetness and fruity/orange flavor. Those effects are reported in both Valencia and Hamlin oranges, two cultivars that are commercially processed for juice. The presumed HLB pathogen remains unconfirmed and its management is challenging due to the unpredictable latency times for symptoms after the tree has become infected, and the lack of effective curative treatment methods. When present, disease management depends on incidence rate, and relies on vector control, tree eradication, nutritional programs and use of plant varieties with increased tolerance. Earlier research showed that HLB-induced off-flavor was not detectable in juice made with up to 25% symptomatic fruit. In some production regions, it is increasingly difficult to find fruit not showing HLB symptoms. This review focuses on the effects of HLB on orange juice quality regarding chemical, physicochemical and biochemical characteristics, including levels of sugars, organic acids, secondary metabolites, levels and profiles of amino acids, bioactive amines, volatile compounds and sensory characteristics, as well as future research needs.

The aim of this study was to understand the flavor components of eating quality of several strawberry ( Fragaria × ananassa Duch.) genotypes grown in Florida over two harvest seasons. Five selections and one cultivar of the University of Florida Breeding program as well as two new cultivars from Australia (Rubygem and Sugarbaby) harvested on different dates from the same grower were evaluated by sensory evaluation. Festival, the main strawberry cultivar grown in Florida, had low ratings for flavor and sweetness in January and March. Selection FL 00-51 and ‘Rubygem’ had relatively high and consistent ratings for flavor and sweetness compared with the other selections. Genotypes with low flavor ratings were always judged as “not sweet enough” by the panelists, thus linking flavor to sweetness preference. Instrumental analysis confirmed that typically these selections had low soluble solids content (SSC) and/or high titratable acidity (TA), thus explaining their lack of sweetness. Volatile compounds that varied only quantitatively did not seem to influence the flavor rating except for ‘Sugarbaby’. This cultivar contained between seven and 40 times less total ester content than the other selections and was disliked by panelists despite its high sugar content and perceived sweetness. It was perceived as having an artificial peach- or blueberry-like flavor. A principal component analysis was performed with chemical parameters (SSC, TA, and volatile content) and selections over the two harvest seasons. Chemical composition was mainly influenced by harvest date, except for FL 00-51. This selection maintained high volatile content and SSC throughout the seasons, explaining consistently high flavor ratings.

There is interest in improving the flavor of commercial strawberry (Fragaria × ananassa) varieties. Fruit flavor is shaped by combinations of sugars, acids and volatile compounds. Many efforts seek to use genomics-based strategies to identify genes controlling flavor, and then designing durable molecular markers to follow these genes in breeding populations. In this report, fruit from two cultivars, varying for presence-absence of volatile compounds, along with segregating progeny, were analyzed using GC/MS and RNAseq. Expression data were bulked in silico according to presence/absence of a given volatile compound, in this case γ-decalactone, a compound conferring a peach flavor note to fruits.