The perceptual properties of the virgin olive oil phenolic oleocanthal are not associated with PROP taster status or dietary intake

https://doi.org/10.1016/j.foodqual.2015.08.006Get rights and content

Highlights

  • Large sensory screening of oropharyngeal irritation from oleocanthal.

  • High variability observed and classification of those sensitive and insensitive.

  • Variability in sensitivity and dietary intake assessed for the first time.

  • No association between oleocanthal irritation and PROP bitterness.

  • Correlation for PROP sensitivity and broccoli intake.

Abstract

Oleocanthal, has been identified as the sole oropharyngeal irritant in virgin olive oil with large individual variation in the perceived intensity of irritation. In this study participants were screened for sensitivity to the oropharyngeal irritation of oleocanthal and bitterness of 6-n-propylthiouracil (PROP), and categorized as hypersensitive (extremely sensitive) or hyposensitive (extremely insensitive). In addition, we determined if a relationship existed between sensitivity to oleocanthal and PROP and dietary intake. Participants (n = 168) took part in the initial screening for irritation to oleocanthal (gLMS range 1.70–70.31). From this sample 87 participants also completed a 4-day diet diary and rated the intensity of oropharyngeal irritation of olive oil and the bitterness of PROP using a gLMS scale. There was large variability in the perceived intensity of irritation from olive oil (gLMS range 4.26–57.15) and the perceived bitterness of PROP (gLMS range 0.0–62.52) with no association between PROP sensitivity and oleocanthal irritation (r = −0.04, p = 0.71). We report no relationship between oleocanthal sensitivity and total energy intake (r = 0.13, p = 0.29), carbohydrate intake (r = 0.12, p = 0.92), protein intake (r = −0.11, p = 0.37), or fat intake (r = 0.14, p = 0.22). There was no association between PROP sensitivity and total energy intake (r = −0.08, p = 0.46), carbohydrate intake (r = 0.12, p = 0.31), protein intake (r = 0.12, p = 0.32), or fat intake (r = −0.08, p = 0.53). We did find a significant negative correlation between PROP sensitivity status and the intake of broccoli (r = −0.24, p < 0.05). In the present study individual variation in sensitivity to the irritation of virgin olive oil or bitterness of PROP was not related to diet with the exception of PROP sensitivity and broccoli intake.

Introduction

Oleocanthal, a phenolic compound contained in virgin olive oil (VOO) produces irritation in the oropharyngeal region. The flavor of VOO is significantly different from other edible oils as it includes flavors such as pungency and irritation from the phenolic fraction along with odors creating a distinct perceptual combination that is reflective of VOO. One of the features of VOO is the localized pungency restricted to the oropharyngeal region and this is elicited by a single compound in VOO, oleocanthal and also the NSAID ibuprofen (Beauchamp et al., 2005, Bennett and Hayes, 2012, Cicerale, Breslin et al., 2009, Peyrot des Gachons et al., 2011). Both oleocanthal and ibuprofen not only share perceptual characteristics but also pharmacological properties as both compounds are exert anti-inflammatory actions on cyclooxygenase enzymes 1 and 2 (COX 1 and 2) (Beauchamp et al., 2005). In fact oleocanthal is now recognized as a naturally occurring NSAID that has beneficial effects in several models of inflammatory disease (for review see (Parkinson & Keast, 2014)).

Variability in the perceived sensitivity of irritation of oleocanthal and also bitter taste from compounds in foods have been noted amongst individuals (Cicerale, Breslin et al., 2009, Cicerale et al., 2012, Hayes et al., 2011). The individual variation in perception of bitter taste is presumably a result of individual genetic factors (Bufe et al., 2005, Dinehart et al., 2006, Duffy et al., 2010, Hayes et al., 2008, Hayes et al., 2011). It is logical to assume that this applies to large variation in oleocanthal sensitivity as well, with the discovery that oleocanthal selectively activates the human nociceptor, transient receptor potential cation channel, member A1 (TRPA1) in HEK 293 cells (Peyrot des Gachons et al., 2011). Beauchamp and colleagues along with other researchers have investigated the affinity of oleocanthal and ibuprofen with the TRPA-1 channel protein, which responds to chemicals and temperature, and is located in abundance in the upper throat and nose. This explains the localized throat sensation arising from oleocanthal and ibuprofen ingestion (Beauchamp et al., 2005, Peyrot des Gachons et al., 2011). It is therefore also to be expected that the genetic variance in distribution of TRPA1 receptor levels across individuals is reason to why one individual may find the intensity of throat irritation from oleocanthal severe whereas another may find it mild or non-existent (Bennett and Hayes, 2012, Cicerale, Breslin et al., 2009). The extent of difference in throat irritation from VOO warrants further attention. Therefore the objective of the first part of this study is to determine the variation in individual differences of perceived intensity of irritation from oleocanthal.

The aim of the second part of this study is to build on the existing taste status and ingestive behavior literature with a hypothesis that there may be a link between the perceived intensity of irritation to a VOO, the perceived bitterness of PROP and diet.

Section snippets

Subjects

Participants (n = 168, aged 18–70, male n = 46 and females n = 122) were recruited from Deakin University and surrounding suburbs in Melbourne Australia. Flyers were distributed via letterbox drop and were also placed at various locations around Deakin University. Demographic information was also collected, including gender, age, height and weight. Body mass index (BMI, kg/m2) was calculated from the height and weight measurements. This study was conducted according to the guidelines laid down in the

Subjects

Full data was obtained from 168 participants in total (male n = 46, female n = 122, 23.2 ± 2.18 years, BMI 22.6 ± 1.27 kg/m2) for the initial sensory screening. From this sample 87 participants (females n = 74, males n = 13, 20.2 ± 3.78 years, body mass index 21.9 ± 0.6 kg/m2) rated the intensity of oropharyngeal irritation of olive oil and the bitterness of PROP using a gLMS scale according to the methodology in Sections 2.2 and 2.4 and then participated in the dietary assessment.

Sensory screening

The mean perceived irritation

Discussion

The wide variation in perceived intensity of the irritation produced by oleocanthal reported here has been noted elsewhere (Bennett and Hayes, 2012, Cicerale, Breslin et al., 2009). The unimodal distribution of oleocanthal sensitivity on the bell shaped curve displays both extremely insensitive (gLMS 1.70) and sensitive individuals (gLMS 70.31). Building on previous studies from our lab and others, there was large inter-individual variation in sensitivity to oleocanthal, that was not associated

Conclusion

As previously reported, there is large individual variation in throat irritation from VOO containing oleocanthal and bitterness of PROP and this study shows further evidence of the individual differences in perception of compounds in foods. There was however no association between those who are sensitive to oleocanthal or sensitive to PROP. Also, the present data suggest that there is no association between individual perceived intensity of irritation from oleocanthal contained in VOO, and

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