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

Comparison of phenotypic and phytochemical profiles of 20 Lycium barbarum L. goji berry varieties during hot air-drying

The variety and drying stage of goji berries (GBs) may affect their final physical and chemical properties. This study investigated the differences in physical phenotypic parameters and major chemical composition parameters of 20 GBs varieties during four stages of hot air-drying (HD). The results indicated that the color difference values L*, a*, and b* decreased during the HD process. The contents of all amino acids decreased, with significant reductions in amino acids involved in the Maillard reaction. Correspondingly, the level of 5-hydroxymethylfurfural, a Maillard chemical reaction intermediates, increased. Furthermore, the decreased L* values were closely linked to the decomposition of carotenoids. Notably, the differences in constituents among different varieties of dried GBs were smaller than those in fresh GBs. These findings provide a theoretical basis for optimization of the GBs drying process, contributing to the expansion of GBs breeding programs and their use in global functional food and pharmaceutical industries.

Analysis of Volatile and Non-Volatile Components of Dried Chili Pepper (Capsicum annuum L.)

As an important crop in the world, dried pepper is widely used in various foods. However, the sensory quality, fruit shape index, edible index, nutrition index, and volatile components of dried pepper have not been comprehensively analyzed. This study elucidated the differences between different varieties of dried pepper and provided the basis for the selection of raw materials for different varieties of dried pepper products. The varieties with high scores in sensory evaluation were Henan new generation, Neihuang new generation, Chengdu Erjingtiao, India S17, and Honglong 12. The varieties with the highest fruit shape index, edible rate, and nutrition index were Chengdu Erjingtiao and Guizhou Erjingtiao. A total of 380 volatile organic compounds were identified by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry with headspace sampling (HS-GC-TOF MS), including 62 alcohols, 50 aldehydes, 68 ketones, 60 hydrocarbons, 99 esters, 18 acids, and 23 other substances such as pyrazoles and ethers.

The effect of mint addition on the physicochemical and organoleptic properties of strawberry sorbets

The study aimed to produce, analyse, and evaluate the consumer acceptance of a functional peppermint-, and spearmint-enriched (0.5,1,2 %) sorbet, which contains only natural substances in its composition, to meet today's popular health-conscious consumer trends. Regarding acid composition, the sorbets contained malic acid, succinic acid, and citric acid. Sorbets regarded of water-soluble sugars, contained sucrose in the lowest concentration, followed by glucose, and the amount of fructose, which is typical for fruits, was the highest. The sorbets' TPC and TAC contents were determined to be between 510.72 and 743.77 mg GAE/kg, and 906.64 and 1137.67 mg AAE/kg respectively. The average melting rate of the desserts was 0.16-0.22 g/min, and based on consumer acceptance, the control and the samples added with 0.5 % spearmint and peppermint mint were the most favorable. The sorbets containing 1 % and 2 % mint had too intense menthol flavor, thus the enjoyment value of the products was reduced based on consumer feedback.

Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze- and Air-Dried New Zealand Apricots

Pulsed electric field (PEF) pretreatment has been shown to improve the quality of dried fruits in terms of antioxidant activity and bioactive compounds. In this study, apricots were pretreated with PEF at different field strengths (0.7 kV/cm; 1.2 kV/cm and 1.8 kv/cm) at a frequency of 50 Hz, and electric pulses coming in every 20 µs for 30 s, prior to freeze-drying and air-drying treatments. PEF treatments were carried out at different field strengths. The impact of different pretreatments on the quality of dried apricot was determined in terms of physical properties, antioxidant activity, total phenolic content, and metabolite profile. PEF pretreatments significantly (p < 0.05) increased firmness of all the air-dried samples the most by 4-7-fold and most freeze-dried apricot samples (44.2% to 98.64%) compared to the control group. However, PEF treatment at 1.2 kV/cm did not have any effect on hardness of the freeze-dried sample. The moisture content and water activity of freeze-dried samples were found to be significantly lower than those of air-dried samples. Scanning electron microscopy results revealed that air drying caused the loss of fruit structure due to significant moisture loss, while freeze drying preserved the honeycomb structure of the apricot flesh, with increased pore sizes observed at higher PEF intensities. PEF pretreatment also significantly increased the antioxidant activity and total phenol content of both air-dried and freeze-dried apricots. PEF treatment also significantly (p < 0.05) increased amino acid and fatty acid content of air-dried samples but significantly (p < 0.05) decreased sugar content. Almost all amino acids (except tyrosine, alanine, and threonine) significantly increased with increasing PEF intensity. The results of this study suggest that PEF pretreatment can influence the quality of air-dried and freeze-dried apricots in terms antioxidant activity and metabolites such as amino acids, fatty acids, sugar, organic acids, and phenolic compounds. The most effective treatment for preserving the quality of dried apricots is freeze drying combined with high-intensity (1.8 kv/cm) PEF treatment.

Loss of Volatile Metabolites during Concentration of Metabolomic Extracts

Volatile metabolites can be lost during the preanalytical stage of metabolomic analysis. This work is aimed at the experimental and theoretical study of mechanisms of volatile substance evaporation and retention in the residues during the drying of extract solutions. We demonstrate that solvent evaporation leads to the unavoidable loss of nondissociating volatile metabolites with low boiling points and high vapor pressures (such as acetone and ethanol). The retention of dissociating volatile compounds (primarily organic acids RH) during the evaporation depends on the presence of buffer salts in solution, which are responsible for maintaining the neutral pH. An acid remains in the solution as long as it is present predominantly in the dissociated R- state. At the very last stage of solvent evaporation, buffer salts precipitate, forming a solid matrix for metabolite trapping in the residue. At the same time, buffer precipitation leads to a decrease of the solution pH, increase of the portion of RH in associated state, and acceleration of RH volatilization. The RH recovery is thus determined by the competition between the solute volatilization in the associated RH form and metabolite trapping in the solid matrix. The retention of volatile acids in the residue after extract drying can be improved either by adding buffer salts to maintain high pH or by incomplete sample drying.

Juice Vesicles Bioreactors Technology for Constructing Advanced Carbon-Based Energy Storage

The construction of high-quality carbon-based energy materials through biotechnology has always been an eager goal of the scientific community. Herein, juice vesicles bioreactors (JVBs) bio-technology based on hesperidium (e.g., pomelo, waxberry, oranges) is first reported for preparation of carbon-based composites with controllable components, adjustable morphologies, and sizes. JVBs serve as miniature reaction vessels that enable sophisticated confined chemical reactions to take place, ultimately resulting in the formations of complex carbon composites. The newly developed approach is highly versatile and can be compatible with a wide range of materials including metals, alloys, and metal compounds. The growth and self-assembly mechanisms of carbon composites via JVBs are explained. For illustration, NiCo alloy nanoparticles are successfully in situ implanted into pomelo vesicles crosslinked carbon (PCC) by JVBs, and their applications as sulfur/carbon cathodes for lithium-sulfur batteries are explored. The well-designed PCC/NiCo-S electrode exhibits superior high-rate properties and enhanced long-term stability. Synergistic reinforcement mechanisms on transportation of ions/electrons of interface reactions and catalytic conversion of lithium polysulfides arising from metal alloy and carbon architecture are proposed with the aid of DFT calculations. The research provides a novel biosynthetic route to rational design and fabrication of carbon composites for advanced energy storage.

Nutrition, phytochemical profiling, in vitro biological activities, and in silico studies of South Chinese white pitaya (Hylocereus undatus)

Background

White pitaya, a popular tropical fruit, is known for its high nutritional value. It is commercially cultivated worldwide for its potential use in the food and pharmaceutical industries. This study aims to assess the nutritional and phytochemical contents and biological potential of the South Chinese White Pitaya (SCWP) peel, flesh, and seed extracts.

Methods

Extract fractions with increasing polarity (ethyl acetate < acetone < ethanol < methanol < aqueous) were prepared. Antibacterial potential was tested against multidrug-resistant (MDR) bacteria, and antioxidant activity was determined using, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assays, and cytotoxic activity against human keratinocyte cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Pharmacological screening and molecular docking simulations were conducted to identify potential antibacterial compounds with druggable characteristics. Molecular dynamics simulation (MDS) was employed to validate the binding stability of the promising ligand-protein complexes.

Results

All parts of the fruit exhibited a substantial amount of crucial nutrients (minerals, sugars, proteins, vitamins, and fatty acids). The ethanol (ET) and acetone (AC) fractions of all samples demonstrated notable inhibitory effects against tested MDR bacteria, with MIC50 ranges of 74-925 μg/mL. Both ET and AC fractions also displayed remarkable antioxidant activity, with MIC50 ranges of 3-39 μg/mL. Cytotoxicity assays on HaCaT cells revealed no adverse effects from the crude extract fractions. LC-MS/MS analyses identified a diverse array of compounds, known and unknown, with antibacterial and antioxidant activities. Molecular docking simulations and pharmacological property screening highlighted two active compounds, baicalein (BCN) and lenticin (LTN), showing strong binding affinity with selected target proteins and adhering to pharmacological parameters. MDS indicated a stable interaction between the ligands (BCN and LTN) and the receptor proteins over a 100-ns simulation period.

Conclusion

Our study provides essential information on the nutritional profile and pharmacological potential of the peel, flesh, and seeds of SCWP. Furthermore, our findings contribute to the identification of novel antioxidants and antibacterial agents that could be capable of overcoming the resistance barrier posed by MDR bacteria.

Changes and correlation analysis of volatile flavor compounds, amino acids, and soluble sugars in durian during different drying processes

Durian contains rich flavor components that undergo complex changes during drying. In this study, durian was subjected to integrated freeze-drying (IFD), conventional freeze-drying (CFD), and hot air drying (AD). Compared with the fresh samples, those dried by IFD, CFD, and AD lost 11, 9, and 7 original volatile compounds, respectively, and generated 7, 6, and 8 new volatile compounds, respectively, and showed a rapid and then slow decreasing trend in the total content during drying. However, the types of amino acids and soluble sugars remained unchanged during each of the drying methods. Furthermore, volatile compounds showed a significant negative correlation with the majority of amino acids and a significant positive correlation with soluble sugars. The IFD samples had the highest content of volatile compounds, amino acids, and soluble sugars. Therefore, IFD is recommended as a preferable drying method for durian.

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

BACKGROUND

Lemon juice vesicles are distinguished by their unique and abundant volatile flavor compounds, which can undergo complex changes during drying. In this study, integrated freeze drying (IFD), conventional freeze drying (CFD), and hot-air drying (AD) were used to dry lemon juice vesicles to investigate the changes in, and correlations among volatile compounds, fatty acids, and key enzyme activity during the drying process.

RESULTS

Twenty-two volatile compounds were detected during the drying processes. Compared with fresh samples, seven compounds were lost in the dried samples after IFD, seven after CFS, and six after AD, and the loss rates of the total content of volatile compounds in the dried samples were 82.73% in CFD, more than 71.22% in IFD, and more than 28.78% in AD. In total, 1.015 mg/g of seven fatty acids were detected in the fresh samples; the content loss rates of total fatty acids after drying were 67.68% in AD, more than 53.00% in CFD, and more than 36.95% in IFD, respectively. During the three drying processes, IFD retained relatively higher enzyme activity in the samples.

CONCLUSION

Many positive and negative correlations (P < 0.05) were observed among the key enzyme effects, fatty acids, and volatile compounds, showing close associations. The current work provides information that is important for the selection of suitable drying techniques for lemon juice vesicles and suggests how to control their flavor during the drying process. © 2023 Society of Chemical Industry.

Effect of Water Stress and Shading on Lime Yield and Quality

The aim of this study was to test the combined effect of water stress and cropping system on yield and fruit quality in Bearss lime trees. For this purpose, two irrigation treatments were applied during stage II of fruit growth: control (well irrigated, automatically managed by soil water content sensors) and stress (non-irrigated), both under open-field and shaded conditions. Soil water status was assessed by determining soil water content and plant water status by measuring stem water potential (Ψ_stem), stomatal conductance (g_s), and net photosynthesis (P_n). Yield parameters (kg and the number of fruits per tree and fresh mass per fruit) and fruit quality were assessed on two harvest dates. In addition, on the second harvest date, the content of metabolites and nutrients in the lime juice was analyzed. The results showed that soil water deficit induced 35% lower g_s values in open-field than in shaded conditions. The highest kg and the number of fruits per tree were observed in the shaded system, especially on the first harvest date. The lowest yield was observed in stressed trees grown without netting. Slightly higher fresh mass and equatorial diameter were observed in shaded fruits than in open-field fruit. Soil water deficit increased fruit total soluble solids and decreased juice content, especially in open-field trees. Shaded conditions made the lime trees more resilient to soil water deficit, which led to higher yields and better external fruit quality traits. In addition, fruit precocity was significantly higher in the shaded system.

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

In this study, fresh Lyophyllum decastes was dried using hot air drying (HAD), hot air combined with vacuum drying (HAVD), and vacuum freeze drying (VFD). Additionally, the quality and volatile compounds were analyzed. VFD achieved the best color retention, the highest rehydration capacity, and the slightest damaged tissue structure; however, it recorded the longest drying time and the highest energy consumption. HAD was the most energy-efficient of the three methods. Furthermore, the products with more hardness and elasticity were obtained by HAD and HAVD-this finding was convenient for transportation. In addition, GC-IMS demonstrated that the flavor components had significantly changed after drying. A total of 57 volatile flavor compounds was identified, and the aldehyde, alcohol, and ketone compounds were the primary ingredient of the L. decastes flavor component, whereby the relative content of the HAD sample was apparently higher than HAVD and VFD. Taken together, VFD was better at preserving the color and shape of fresh L. decastes, but HAD was more appropriate for drying L. decastes because of the lower energy consumption, and was more economical. Meanwhile, HAD could be used to produce a more intense aroma.