Electronic nose application for the discrimination of sterilization treatments applied to Californian‐style black olive varieties

Abstract

BACKGROUND: Olive oil continues to be the main destination for olives. The production of table olives is increasing. 'Californian-style' processes are among the most frequently employed to produce oxidized olives. Sensory evaluation requires the development of an instrumental detection method that can be used as an adjunct to traditional tasting panels.RESULTS: An electronic nose (E-nose) was used to classify two varieties of olives following exposure to different sterilization. Principal component analysis (PCA) revealed that both varieties had different volatile profiles. Sensory panel evaluations were similar for both. Partial least squares-discriminant analysis (PLS-DA) obtained from the E-nose was able to separate the two varieties and explained 82% of total variance. Moreover, volatile profiles correctly classified olives according to sterilization times recorded up to 121 °C . The only exception was at F 0 ≥ 22 min, at which a plot of PCA outcomes failed to differentiate scores. E-nose data showed similar results to those produced from the volatile analysis when grouping samples were sterilized to F 0 ≥ 18 min, at the same time distinguishing these samples from those subjected to less intense thermal treatments. A partial least squares (PLS) chemometric approach was evaluated for quantifying important olive quality parameters. With regards to validation parameters, R 2 P pertaining to perceived defect was 0.88, whilst R 2 P pertaining to overall assessment was 0.78. CONCLUSIONS: E-nose offers a fast, inexpensive and non-destructive method for discriminating between varieties and thermal treatments up to a point at which cooking defects are highly similar (from F 0 = 18 onwards).

Application of Digital Olfaction for Table Olive Industry

“…Other researchers presented an E-nose system able to discriminate different fungal species [ 30 , 31 ]. Other researchers have also established a PLS-DA model in order to produce a predictive classification model capable of separating the table olives varieties [ 32 ] and table olives stuffed with flavored hydrocolloids [ 33 , 34 ] that can be used as a rapid and inexpensive screening method for discrimination of standard characteristic aroma in Spanish-style and Californian-style table olives. All in all, the outcomes presented in our research prove that this electronic device is a powerful tool to discriminate VOCs produced by Spanish-style table olives.…”

Determination of the Masking Effect of the ‘Zapateria’ Defect in Flavoured Stuffed Olives Using E-Nose

“…The application of this type of PLS algorithm, in which the E-nose values of perceived defects and aromas in table olives samples are predicted, has been described before: the impact of sterilisation treatments on the effect of cooking in table olives was studied [27].…”

Characterization of Polyphenol and Volatile Fractions of Californian-Style Black Olives and Innovative Application of E-nose for Acrylamide Determination

“…Furthermore, although almost 50 volatile compounds were identified, the major constituents in the olive matrix are shown in Figure 2 The unpleasant odour aromas such as 4-ethenyl-pyridine (aromatics), benzaldehyde (aldehydes), and 2,4-dimethyl-hexane (others), which had a high influence after the application of the thermal treatments, increased in content. Moreover, other fruity aromas, such as ethyl ester cyclohexanecarboxylic acid (esters) and creosol (phenols), decreased their content [ 23 , 34 , 35 ].…”

“…Regarding the volatile compounds, Californian-style black olives have a characteristic odour of a cooked sensory note [ 15 , 23 , 41 ] that is mainly provoked by the thermal treatment that was used to stabilize these types of olives. Following IOC regulations, the results obtained by these researchers can classify table olives that have been submitted to different sterilization treatments into different sensory categories after considering the predominantly perceived defect (PPD) and intensity attributes.…”

“…Recently, studies have been carried out using electronic noses to predict the quality of the oil to be processed from the measurements obtained in freshly harvested olives [ 20 ] and to evaluate the odours produced in anomalous fermentations of Spanish-style green olives [ 15 ]. The variation of the volatile organic compounds generated in food after thermal treatments has also been studied to monitor the evaluation of the quality of the oil used for frying [ 21 ], to identify the olfactory profile of rapeseed oil as a function of heating time [ 22 ], or in the sensory evaluation of Californian-style black olive sterilization treatments [ 23 ].…”