Combining Chemometrics, Sensory Analysis and Chromatographic Fingerprint of Volatile, and Phenolic Compositions for Systematic Classification of Pineapple (Ananas comosus L.)

Abstract

Classification and quality control of fruits in Malaysia is based on the morphological traits manual carried out by the agricultural officer. As this approach is based on human perception and judgment, it may be biased and inconsistent. The aroma of pineapple is made up of a wide range of volatile and non-volatile compounds depending on the varieties and maturity stages of the fruits and thus, can be valuable factors in classifying the fruits. The chromatographic fingerprints of volatile and phenolic compounds from pineapple pulp were obtained by using Gas Chromatography-Mass Spectrometry Detector (GC-MSD) and 2-Dimensional-Liquid Chromatography -Diode Array Detector (2D-LC-DAD), respectively. Sensory profiles, conducted using quantitative descriptive analysis (QDA), showed that the fruity aroma of pineapple were not able to differentiate between the pineapple varieties with scales of 4.13±2.07, 5.33±2.58, 3.87±2.07, and 3.00±0.00 for the Morris, Josephine, MD2, and Sarawak varieties, respectively. Thus, sensory analysis alone could be biased and unreliable in discriminating pineapple varieties. Chemometric techniques based on unsupervised (principal component analysis (PCA) and hierarchical cluster analysis (HCA)), and supervised (discriminant analysis (DA) and partial least squares discriminant analysis (PLS-DA) using 13 sensory attributes, 10 selected phenolic compounds, and 35 volatile compounds allowed the discrimination of these four pineapple varieties.

Review of the Aroma Chemistry of Pineapple (Ananas comosus)

“…The published literature on pineapple VOC analyses selected herein can be grouped into several categories based on the main objective of the study, such as studies focused on the following: Review of published information ,− Identification of VOC using instrumental analysis ,− OT, odor activity value (OAV) calculation, and odor description ,,, Effect of ripeness and maturity ,,, Effect of post-harvest storage and logistics ,,,− Influence of VOC isolation–extraction techniques ,,,,, Varieties and geographical locations ,,,− Seasons and environmental factors ,,,, Effect of processing and handling ,,− Sampling uniformity/tissue type , Self-interaction of VOCs within the fruit matrix , …”

“…The VOCs of pineapple are organic compounds with defined chemical structures, and their basic skeletons are formed through biosynthetic pathways from their primary precursor compounds (fatty acids, lipids, carotenoids, carbohydrates, and amino acids).The quality and quantity of the VOC depend upon the availability of the precursor compounds, and further diverse VOCs are then formed via additional modification reactions such as acylation, methylation, oxidation/reduction, and cyclic ring closure from the basic skeletons. , The identification of genes responsible for biosynthesis of VOCs can open new perspectives for the improvement of flavor, by cloning those genes, increasing that specific pathway, or silencing the expression of a gene responsible for an undesired compound . Several complex factors can affect the composition of VOCs in pineapple such as varieties and geographical locations, ,,,− seasons and environmental factors, ,,,, and ripeness and maturity. ,,, …”