Sensory active substances causing off-odour in liquid whey during storage

Abstract

Liquid whey is a nutritious product with high water activity and neutral pH. Therefore, it is very susceptible to microbiological spoilage that results in undesirable off-odors. Additionally, minimally processed foods are the recent trend so setting an appropriate shelf life is essential. The commonly used microbiological methods are lengthy and time-demanding, so a quick and early identification of microbial degradation would be a significant benefit. Here we tested a solid-phase microextraction, gas chromatography with mass spectrometry coupled with olfactometry analysis (SPME-GC-MS/O) on samples of sweet unpasteurized liquid whey stored at 6 °C, 12 °C and 25 °C for a week. We compared the common methods – plate methods, measurement of pH, and dry matter determination with our proposed SPME-GC-MS/O. We have identified seven sensory active compounds while octanoic acid and a compound not reliably identified by the MS detector (with main m/z observed 133 (100), 151 (65), and 135 (26)) being the most prominent. Microbiological methods proved irreplaceable for proper setting of storage conditions (with the growth of coliforms being significant (p <0.001) at 25 °C). However, SPME-GC-MS/O was able to identify volatile substances responsible for off-odors and can be used as a powerful tool to detect the cause of undesirable chemical and microbial changes in whey beverages.

Spoilage Potential of Contaminating Yeast Species Kluyveromyces marxianus, Pichia kudriavzevii and Torulaspora delbrueckii during Cold Storage of Skyr

“…Carrillo-Carrión and co-workers proposed that the total concentration of volatile aldehydes (C5-C9) can be used as a marker of yogurt degradation at inadequate storage conditions [ 52 ]. Among them, hexanal was positively associated with rancidity in foods and negatively associated with the “degree of likeness” in yoghurts [ 53 , 54 ].…”

The effect of whey type on the yield and quality characteristics of Urda

“…After curd draining, pH values of the whey from WBC production decreased rapidly over time (up to 5 hours), while in this period, significant decrease in the pH values in KAS whey was not determined (Figure 1). In the liquid whey that was not pasteurized or cooled to low temperatures, the active culture continued to grow and to produce lactic acid mainly that initiated increase of the acidity during storage (Muhammad et al, 2018;Hanková and Čížková, 2020). When WBC production is performed in open vats where manual operations are involved, the possibility of microbial contamination and pH decrease is higher in comparison to KAS production in tanks.…”