Removal of C9-aldehydes and -alcohols from melon juice via cysteine addition

BACKGROUND

The aroma of a melon fruit is among the most crucial qualities that influence consumer preferences. However, strong grassy and cucumber-like aromas can prevent consumer acceptance. These grassy and cucumber-like aromas are produced by aldehydes containing nine-carbon chains. Several studies have revealed that aldehydes exhibit a high affinity toward cysteine. Thus, the effect of adding cysteine to volatile compounds to melon juice was investigated.

RESULTS

The volatile compounds released from the melon juice were analyzed via solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) after 0.5, 5, and 24 h of adding cysteine. The results indicated that the concentrations of aldehydes, such as (E,Z)-2,6-nonadienal and (E)-2-nonenal, in the melon juice decreased after the addition of cysteine at all the analyzed times. Additionally, (E)-2-nonenol and (E,Z)-2,6-nonadien-1-ol, which were formed by the enzymatic reduction of the aldehydes, also decreased by cysteine addition. To confirm the binding of cysteine with the aldehydes, two cysteine adducts were analyzed via liquid chromatography-mass spectrometry (LC-MS) employing (E)-2-nonenal in the melon juice after the addition of cysteine.

CONCLUSION

This study demonstrates that cysteine addition could be potentially used to reduce the grassy and cucumber-like aromas of melon juice. © 2022 Society of Chemical Industry.

Emissions of DEHP-free PVC flooring

Degrading 2-ethylhexyl-containing PVC floorings (eg DEHP-PVC floorings) and adhesives emit 2-ethylhexanol (2-EH) in the indoor air. The danger of flooring degradation comes from exposing occupants to harmful phthalates plasticisers (eg DEHP), but not from 2-EH as such. Since the EU banned the use of phthalates in sensitive applications, the market is shifting to use DEHP-free and alternative types of plasticisers in PVC products. However, data on emissions from DEHP-free PVC floorings are scarce. This study aimed at assessing the surface and bulk emissions of two DEHP-free PVC floorings over three years. The floorings were glued on the screed layer of concrete casts at 75%, 85%, and 95% RH. The volatile organic compounds (VOCs) were actively sampled using FLEC (surface emissions) and micro-chamber/thermal extractor (µ-CTE, bulk emissions) onto Tenax TA adsorbents and analyzed with TD-GC-MS. 2-EH, C9-alcohols, and total volatile organic compound (TVOC) emissions are reported. Emissions at 75% and 85% RH were similar. As expected, the highest emissions occurred at 95% RH. 2-EH emissions originated from the adhesive. Because the two DEHP-free floorings tested emitted C9-alcohols at all tested RH, it makes the detection of flooring degradation harder, particularly if the adhesive used does not emit 2-EH.