# Evaluation of Freezing-Induced Changes in Aroma Profiles of Pomegranate Juice by Quantitative Descriptive Sensory Analysis, Gas Chromatography–Mass Spectrometry/Olfactometry, Odor Activity Values, Orthogonal Partial Least Squares–Discriminant Analysis, and Odorant Addition Experiment

## TL;DR

Freezing pomegranate juice changes its aroma, and this study identifies key compounds responsible for these changes.

## Contribution

The study identifies specific odorants that are critical for flavor changes in pomegranate juice after freezing.

## Key findings

- Freezing reduces grassy, woody, and fruity aroma attributes in pomegranate juice.
- Five volatiles were identified as key markers, with (Z)-3-hexen-1-ol enhancing grassy and fruity notes.
- Hexanol and β-myrcene were found to enhance grassy and woody attributes, respectively.

## Abstract

Freezing is employed to preserve the quality of pomegranate juice (PJ) for producing nutritious ready-to-drink beverages. However, the aroma compounds of PJ undergo significant alterations post-freezing. This study aimed to examine the impacts of different freezing temperatures (−20 °C, −40 °C, and −80 °C) on the flavor profiles of PJ, using fresh PJ as a control. The quantitative descriptive sensory analysis (QDA) results showed that grassy, woody, and fruity attributes of PJ were notably diminished following the freezing treatment. In total, 34 volatiles were identified by gas chromatography–mass spectrometry (GC-MS), of which 14 were perceived by GC–olfactometry (GC-O). Together with orthogonal partial least squares–discriminant analysis (OPLS-DA) and OAV tests, five volatiles were determined as key differential markers, and three (hexanol, (Z)-3-hexen-1-ol and β-myrcene) were selected for further odorant addition experiments. The results verified that (Z)-3-hexen-1-ol was the primary odorant for enhancing the grassy and fruity notes of PJ, while hexanol and β-myrcene were crucial for enhancing grassy and woody attributes, respectively.