Dynamic Changes in Volatile Flavor Compounds, Amino Acids, Organic Acids, and Soluble Sugars in Lemon Juice Vesicles during Freeze-Drying and Hot-Air Drying

Abstract

Lemon juice vesicles have abundant flavor components that can undergo complex changes during drying. Three drying methods, including integrated freeze-drying (IFD), conventional freeze-drying (CFD), and hot-air drying (AD), were studied to determine their effects on the dynamic changes in the flavor compounds in lemon juice vesicles. Compared with the fresh samples, the final dried samples that underwent IFD, CFD, and AD lost seven, seven, and six volatile flavor compounds and three, four, and five amino acids, respectively; the order of the loss ratios with respect to the volatile compound content was: 82.73% in CFD > 71.22% in IFD > 28.78% in AD. AD resulted in the highest total amino acid content (10.83 ± 0.20 mg/g), which was 1.39 and 5.54 mg/g higher than that of IFD and CFD, respectively; CFD resulted in the highest total organic acid content (45.94 ± 0.34 mg/g), which was 8.01 and 7.87 mg/g higher than that of IFD and AD, respectively; and AD contributed to the highest total soluble sugars (17.12 ± 0.20 mg/g), which was 1.24 and 1.49 mg/g higher than that of IFD and CFD, respectively. A correlation analysis demonstrated that most of the amino acids and the soluble sugars were closely related to the profiles of the volatile compounds in the lemon juice vesicles during drying.

Effects of Drying Methods on the Physicochemical Aspects and Volatile Compounds of Lyophyllum decastes

“…In summary, regarding the three drying methods, dried L. decastes via HAD was detected with a higher relative content of aldehydes, alcohols, and ketones than via HAVD and VFD. This was consistent with the research on juice [ 44 , 45 ]. Other than the thermal-treatment effect, this finding could be due to the destruction of the cell wall and cytoplasm via HAD, more various intracellular components released, or the involvement with the reaction during drying [ 16 ]—if considered, more flavor compounds could be produced.…”

“…PCA is a multivariate statistical analysis technique. The complex and difficult-to-find variables in the original samples were represented by a few principal component factors, therefore, the differences from the samples could be evaluated according to the contribution rate of principal component factors of the different treatments [ 44 , 45 ]. The PCA of volatile substances in both fresh and different treated L. decastes samples was clarified in Figure 5 .…”

Effect of Water Stress and Shading on Lime Yield and Quality

“…In our study, lime juice was also a source of amino acids but in lower concentrations than sugars, as also found by Xie et al [ 53 ] in orange, grapefruit, and lemon juice. The metabolomic analysis revealed that the main amino acids in lime juice were asparagine, proline, alanine, glutamine, and 4-aminobutyrate ( Figure 2 B), similar to what was reported in orange and lemon juices [ 54 ].…”

Changes in, and correlation analysis of, volatile compounds, key enzymes, and fatty acids in lemon juice vesicles during freeze drying and hot‐air drying

“…Lemon juice vesicles are the most important edible tissue in the lemon fruit, accounting for more than 60% of its mass. 4,5 The fresh juice vesicles are extremely sour in taste. It is necessary to process the lemon juice vesicles to increase the economic benefits and flavor qualities of lemon.…”

“…4,14,15 However, these volatile compounds are easily transformed and lost during the drying of lemons, which eventually affects the flavor quality of dried lemon products. 5,7 Studies of the metabolic pathways of fruit volatile compounds have mainly focused on the relationship between enzymes and the formation of volatile compounds in fruits, and the key enzymes in the metabolic pathways of volatile compounds, such as lipoxygenase (LOX), alcohol acyltransferase (AAT), and alcohol dehydrogenase (ADH), have become trending research topics. Lipoxygenase is an important rate-limiting enzyme in the initial fatty acid metabolic pathway that converts fatty acids to hydroperoxides, participates in the synthesis of straight-chain esters using fatty acids as precursors, and catalyzes the production of C 6 and C 9 compounds from linoleic and linolenic acids.…”