Odour and flavour thresholds for key aroma components in an orange juice matrix: esters and miscellaneous compounds

Abstract

Thresholds for flavour volatiles have been traditionally calculated in water or air but they may vary widely in more complex matrices such as milk, gels or fruit slurries. The data presented are part of a continuing study to provide the industry with threshold guidelines more adequate for the use of flavours in citrus juices. Thresholds of aroma compounds of orange juice (OJ) were determined in reconstituted pump-out (RPO), approaching a deodorized OJ matrix and served at 10-12°C, the temperature at which OJ is consumed. The three-alternative forced choice (3-AFC) method was used (ASTM: E-679). Sixteen to twenty panelists were presented with RPO samples arranged in five rows of three samples corresponding to five spiking levels, each separated by a factor of 3, with a 3-AFC presentation at each level. For each compound, the test was repeated four times. Compounds tested were verified for purity by GC-MS and GC-O. Orthonasal and retronasal thresholds for esters were twice (methyl butanoate) to 30 times (ethyl propanoate) higher in the orange juice matrix than published values in water. The odour activity values (OAVs) of volatile compounds were calculated for two OJs; nine compounds had an orthonasal OAV < 1 when using thresholds determined in RPO, while in contrast, these compounds had an OAV > 1 when calculated with published thresholds determined in water. The relative OAV of some compounds had changed with respect to each other, indicating a different contribution of these compounds to OJ flavour when their OAV was calculated in RPO. These results show the importance of non-water-soluble compounds on odour and flavour perception. The threshold values provided herein are directly usable by the industry, in comparison with the current values published in water, and will help in developing models that would explain OJ flavour based on interactions with the matrix.

Changes in Volatile and Non-Volatile Flavor Chemicals of “Valencia” Orange Juice over the Harvest Seasons

“…, the odor active value (OAV) > 1 for at least one harvest (Table 2). It is important to note that the odor thresholds listed are based on an OJ matrix, and the values are much higher than those reported for water based thresholds [10,11]. …”

“…Table 2 listed 23 important aroma contributors in orange juice [10,11,67] and their changes during the 2007 and 2012 harvest seasons. In 2007, DHS sampling method was used and only 22 volatiles were detected, and of which 13 important compounds were listed in Table 2.…”

“…al . [10] and Qiao et al . [68]; b Retronasal identification threshhold in a reconstituted pump-out adapted from Plotto et al .…”

“…Of those, only 20–40 are generally recognized as important aroma contributors to OJ, including esters, aldehydes, monoterpenes, sesquiterpenes, alcohols, ketones, and hydrocarbons [10,11,12,13]. Over the last half century, much effort has been focused on varietal selections, pre- and postharvest treatments, processing methods (such as extractor and finisher settings) and thermal pasteurization or concentration.…”

Physiological, biochemical and sensory characterization of the response to waxing and storage of two mandarin varieties differing in postharvest ethanol accumulation

“…Levels of off-flavor were greater in P than GN, which may be important in understanding the greater impact of waxing and storage on the acceptability of this variety. The existence of other Plotto et al (2008), in juice. c Buettner and Schieberle (2001), in water.…”