Analysis of Volatile Organic Compounds in Milk during Heat Treatment Based on E-Nose, E-Tongue and HS-SPME-GC-MS

Abstract

Volatile organic compounds (VOCs) make up milk flavor and are essential attributes for consumers to evaluate milk quality. In order to investigate the influence of heat treatment on the VOCs of milk, electronic nose (E-nose), electronic tongue (E-tongue) and headspace solid-phase microextraction (HS-SPME)–gas chromatography–mass spectrometry (GC-MS) technology were used to evaluate the changes in VOCs in milk during 65 °C heat treatment and 135 °C heat treatment. The E-nose revealed differences in the overall flavor of milk, and the overall flavor performance of milk after heat treatment at 65 °C for 30 min is similar to that of raw milk, which can maximize the preservation of the original taste of milk. However, both were significantly different to the 135 °C-treated milk. The E-tongue results showed that the different processing techniques significantly affected taste presentation. In terms of taste performance, the sweetness of raw milk was more prominent, the saltiness of milk treated at 65 °C was more prominent, and the bitterness of milk treated at 135 °C was more prominent. The results of HS-SPME-GC-MS showed that a total of 43 VOCs were identified in the three types of milk—5 aldehydes, 8 alcohols, 4 ketones, 3 esters, 13 acids, 8 hydrocarbons, 1 nitrogenous compound, and 1 phenol. The amount of acid compounds was dramatically reduced as the heat treatment temperature rose, while ketones, esters, and hydrocarbons were encouraged to accumulate instead. Furfural, 2-heptanone, 2-undecanone, 2-furanmethanol, pentanoic acid ethyl ester, 5-octanolide, and 4,7-dimethyl-undecane can be used as the characteristic VOCs of milk treated at 135 °C. Our study provides new evidence for differences in VOCs produced during milk processing and insights into quality control during milk production.

Effects of Broth pH and Chilling Storage on the Changes in Volatile Profiles of Boiled Chicken Flesh

“…Prior research (Petrucci et al, 2016;Jung et al, 2023) indicates that heating provided molecular energy to break atom-to-atom bonds, resulting in smaller molecules or volatiles, but it also led to volatile degradation (Yuan et al, 2023). Moreover, found that the pH of the solution affected the volatility of the compounds through two processes: 1) decomposition, in which a low or high pH caused some compounds to break down into smaller, more volatile molecules, and 2) acid and base reactions, which result in charged ions, which are less volatile than neutral molecules.…”

Quality Assessment of Loquat under Different Preservation Methods Based on Physicochemical Indicators, GC–MS and Intelligent Senses

“…The E-tongue method was used to evaluate the differences in the taste attributes of loquat under different preservation methods [48]. The basic sensory taste indices were presented as radar images (Figure 10A).…”

Non‐volatile and volatile compound changes in blueberry juice inoculated with different lactic acid bacteria strains

“…Some volatile compounds, including protonated monomers (M) and proton-bound dimers (D). 37 Most of these volatile chemicals belong to distinct chemical categories, such as esters (18), ketones (14), aldehydes (18), alcohols (12), ethers (1), furans (1), and unidentified compounds (10).…”

“…The electronic nose (E‐nose) is a bionic instrument that mimics the human olfactory cells. Using an array of sensors, an E‐nose can quickly differentiate distinct aroma profiles and provide overall odour descriptions 12 . However, few studies have investigated aroma changes in fermented blueberry juice by combining GC–IMS and E‐nose analyses.…”