Analysis of taste, cordycepin, phenolic compounds, and water distribution of radio frequency heated Cordyceps militaris combined with electronic tongue and NMR

Abstract

Radio frequency (RF) was applied to heat Cordyceps militaris for the purpose of quality evaluation and microorganism control. RF heating caused gradual temperature increases ranging from 59.6 to 63.8°C, resulting in good heating uniformity and uniform temperature distribution. Compared with conventional high pressure steam (HPS), RF heating resulted in significant (p < .05) higher total phenolic, flavonoids, and cordycepin contents of C. militaris. In addition to higher reduction of total aerobic bacteria counts, bitterness taste value increased from 2.35 (unpasteurized) to 4.79 (HPS). Umami value significantly decreased from 13.58 (unpasteurized sample) to 12.13 (HPS treated sample). Nuclear magnetic resonance analysis showed that 20 min of RF significantly reduced the loss of water mobility than HPS. Principal component analysis of taste characteristics indicated distinct differences between RF and HPS treated samples. Hierarchical clustering analysis also revealed higher similarity between RF heated samples and the unpasteurized one. Practical applications Cordyceps militaris is an edible and medicinal mushroom with high nutritional quality. Results of the present study indicate that radio frequency (RF) contributed to higher umami taste, higher retention of bioactive compounds, and higher water mobility of C. militaris. Therefore, this process can be used to develop a promising alternative to conventional thermal method for the processing of C. militaris. It is highly possible that RF could be applied to healthy food industries.

Freezing of green peppers assisted by combined electromagnetic fields: Effects on juice loss, moisture distribution, and microstructure after thawing

“…After thawing the flavor showed a trend of increasing sourness and umami values and decreasing astringency and saltiness values. The phenomenon of increase in sourness values is possible due to the formation of the acid compound phenylbutyric acid (Ma et al, 2019; Xu et al, 2015).…”