Effects of freeze‐drying of samples on metabolite levels in metabolome analyses

Abstract

Freeze-drying (FD) is a useful technique for removing water from biological tissues, such as food samples. Cellular components freeze at once, and the ice sublimates under conditions of high vacuum and low temperatures. Because biological activity is restricted during FD, the degradation of cellular metabolites is often believed to be limited. However, the cellular structure is damaged by several factors, such as the increase in cell volume during freezing, and this has serious effects on the levels of some cellular metabolites. We studied these effects of FD on metabolite levels when using it as a sample preparation step in metabolome analysis. We observed significant decreases in the levels of some metabolites, such as succinate and choline, in Arabidopsis and pear, respectively. We also found that the effects of FD on certain metabolite levels differed between Arabidopsis plants and pear fruits. These results suggest that it is necessary to confirm the metabolite recovery in each sample species when FD is used for sample preparation.

Bioactive potential of Diadema sp. from the South East Coast of Mauritius

“…Secondary metabolites are normally not subjected to degradation when FD is employed although the contrary was observed in this study. This conforms to what have been stated by [13] and [14] that FD has different impacts on different samples. The extreme vacuum applied during the FD process might have caused the important loss of volatile and sensitive compounds, hence, explaining the low yield of FD samples.…”

“…The results from Fig. 2 are coherent to what has been reported by [13]. Indeed, NFD samples gave higher phenolic content; 420 mg GAE/g DW and 688.1 mg GAE/g DW for NFD methanolic shell and gonadal extract, respectively.…”

“…Both volatile bioactives and polyphenols concentrations are known to vary when samples are freeze-dried [13]. The results from Fig.…”

A murine model of acute lung injury identifies growth factors to promote tissue repair and their biomarkers

“…Briefly, fifty microliters of the sera from mice of the indicated genotype before or after DT treatment was used for the analysis of ionic metabolites. Hydrophobic and high molecular weight compounds were removed by the preparative processes of liquid-liquid separation using chloroform and water, and ultrafiltration using a 5 kDa cutoff filter, respectively, prior to the metabolome analyses (Oikawa, Otsuka, et al, 2011b). Comprehensive analysis of ionic metabolites using CE-TOF MS was performed as previously reported (Oikawa, Fujita, Horie, Saito, & Tawaraya, 2011a).…”

CE‐MS for metabolomics: Developments and applications in the period 2010–2012

“…Oikawa et al evaluated the effect of freeze‐drying (FD) on metabolite levels in Arabidopsis and pear extracts when using it as a sample preparation step in CE‐MS‐based non‐targeted metabolite analysis . Separations were carried out using a fused silica capillary filled with 1 M formic acid (pH 1.8) or 20 mM ammonium formate (pH 10.0) as BGE for cation and anion analyses, respectively.…”