Ni Yang

Determination of volatile marker compounds of common coffee roast defects

Highlights • Coffee was roasted and five typical roasted defects were replicated.• Light roast defect had increased indole.• Scorched roast defect had increased 4-ethyl-2-methoxyphenol.• Dark and baked roast defect had increased phenol and maltol respectively.• Underdeveloped roast defect had increased 2,5-dimethylfuran.

Impact of flavour solvent (propylene glycol or triacetin) on vanillin, 5-(hydroxymethyl)furfural, 2,4-decadienal, 2,4-heptadienal, structural parameters and sensory perception of shortcake biscuits over accelerated shelf life testing

The influence of choice of flavour solvent, propylene glycol (PG) or triacetin (TA), was investigated during accelerated shelf life (ASL) testing of shortcake biscuits. Specifically, the differential effect on the stability of added vanillin, the natural baked marker compound 5-(hydroxymethyl)furfural (HMF), specific markers of oxidative rancidity (2,4-decadienal, 2,4-heptadienal), and the structural parameters of hardness and fracturability. Significantly more HMF was formed during baking of biscuits prepared with TA; these biscuits were also more stable to oxidative degradation and loss of vanillin during ageing than biscuits prepared with PG. Fresh TA biscuits were significantly more brittle than fresh PG biscuits. There was no impact of solvent choice on hardness. Sensory evaluation of hardness, vanilla flavour and oily off-note was tested during ASL testing. There was no significant impact of storage on sensory ratings for either the PG or TA biscuits.

Corrigendum: Genetic improvement of tomato by targeted control of fruit softening

Nat. Biotechnol. 34, 950–952 (2016); published online 25 July 2016; corrected after print 14 September 2016 In the version of this article initially published, the volume and page numbers for reference 46 were incorrect. The error has been corrected in the HTML and PDF versions of the article

Modifying Robusta coffee aroma by green bean chemical pre-treatment

Highlights • Different levels of acetic acid were used to pre-treat Robusta green coffee beans.• Acetic acid pre-treated Robusta had a more similar aroma profile to Arabica.• The optimum level of acetic acid treatment was 2%.• The maximum level of Robusta coffee added in a blend increased from 20% to 80%.

A non-invasive measurement of tongue surface temperature

Oral temperature, tongue specifically, is a key factor affecting oral sensation and perception of food flavour and texture. It is therefore very important to know how the tongue temperature is affected by food consumption. Unfortunately, traditional methods such as clinical thermometers and thermocouples for oral temperature measurement are not most applicable during food oral consumption due to its invasive nature and interference with food. In this study, infrared thermal (IRT) imager was investigated for its feasibility for the measurement of tongue surface temperature. The IRT technique was firstly calibrated using a digital thermometer (DT). The technique was then used to measure tongue surface temperature after tongue was stimulated by (1) water rinsing at different temperatures (0-45 °C); and (2) treated with capsaicin solutions (5, 10, and 20 ppm). For both cases, tongue surface temperature showed significant changes as a result of the physical and chemical stimulation. Results confirm that IRT is feasible for tongue temperature measurement and could be a useful supporting tool in future for the study of food oral processing and sensory perception.

The role of phenolic compounds on olive oil aroma release

In this study, atmospheric pressure chemical ionisation-mass spectrometry (APCI-MS) was successfully applied to understand the effect of phenolic compounds on the release of olive oil aroma compounds. Eight aroma compounds were monitored under in-vivo and in-vitro dynamic conditions in olive oil with and without the addition of virgin olive oil (VOO) biophenols. Three model olive oils (MOOs) were set up with identical volatile compounds concentrations using a refined olive oil (ROO). Phenolics were extracted from VOOs and were added to two MOOs in order to obtain two different concentrations of phenolic compounds (P+ = 354 mg kg-1; P++ = 593 mg kg-1). Another MOO was without VOO biophenols (P-). Phenolic compounds impacted both the intensity and time of aroma release. In the in-vivo study, 1-penten-3-one, trans-2-hexenal and esters had lower release in the presence of higher levels of biophenols after swallowing. In contrast, linalool and 1-hexanol had a greater release. The more hydrophobic compounds had a longer persistence in the breath than the hydrophilic compounds. VOO phenolics-proline-rich proteins complexes could explain the binding of aroma compounds and consequently their decrease during analysis and during organoleptic assessment of olive oil.