Chemometric characterization of 30 commercial thermal and cold processed juices using UPLC-QTOF-HR-MS fingerprints

Effect of Frying Process on the Flavor Variations of Allium Plants

The Allium plant is widely used in cuisines around the world for its characteristic flavor. The general profile of the plant changes a lot and presents quite different smells after the frying process. In this work, five Allium plants and their fried oils were compared to find out how the frying process impacts the general flavor profile. The results of sensory analysis indicated that the frying process could substantially increase the flavor acceptability of fresh Allium plants. Meanwhile, according to gas chromatography-mass spectrometry (GC-MS) analysis, fewer volatile compounds were detected in fresh Allium plants than in their fried oils. Furthermore, contents of nitrogen-containing compounds (ranging from 0.17 μg/g to 268.97 μg/g), aldehydes (ranging from 71.82 μg/g to 1164.84 μg/g), and lactones (ranging from 0 μg/g to 12.38 μg/g) increased significantly. In addition, more aroma-active substances were identified in the fried Allium oils revealed by gas chromatography-olfactometry (GC-O) analysis. Sulfur-containing compounds were the most abundant in fresh Allium plants, whereas nitrogen-containing compounds dominated in fried oils. The thermal degradation of sugars, amino acids and lipids as well as interactions between carbohydrates, proteins, and fats during the frying process were thought to be the main contributors to these variations. Therefore, this research provides a theoretical basis for the quality control of onion oil flavor and promotes the further development of the onion plant industry. Consequently, the research provided a theoretical basis for the quality control of Allium oils' flavor and promoted the further development of Allium plant industries.

Optimization of Extraction Solvent and Fast Blue BB Assay for Comparative Analysis of Antioxidant Phenolics from Cucumis melo L

Melon (Cucumis melo L.) fruits contain multiple health-promoting compounds, including phenolic compounds, which are antioxidants. Accurate measurement of antioxidant activities and total phenolic contents (TPCs) require an efficient solvent extraction. In this study, we evaluated free radical scavenging activity and TPC of melon extracts extracted with 22 different solvent combinations. The DPPH scavenging activities were high in 100% methanolic (39.48 ± 0.36 µg g⁻¹) and 80% methanolic extracts (38.99 ± 0.44 µg g⁻¹). Similarly, the ABTS scavenging activities were high in 100% methanolic (315.11 ± 10.38 µg g⁻¹) and 80% methanol extracts (297.39 ± 14.98 µg g⁻¹). The Folin–Ciocalteu (F–C) assay is typically used to measure TPC but may be affected by interference from sugars and other compounds. Therefore, we optimized an assay for TPC using Fast Blue (FB) salt and developed a standard operating procedure for microplate analysis using FB. Our analysis of standard samples and comparisons with the F–C assay suggested that the optimized FB assay could be used to measure TPC in fruit and juice samples. Moreover, we successfully detected six phenolic compounds in methanol extracts of melon by LC-HR-QTOF/MS.

Comparative evaluation of different methods for determining phytochemicals and antioxidant activity in products containing betalains - Verification of beetroot samples

This study presents methods that can be used to assess the health quality of products containing betalains. The paper compares and verifies data on the phytochemical composition of three different pigmented beetroot cultivars using spectrophotometric, HPLC-DAD, HPTLC and LC-Q-Orbitrap-HRMS techniques. Additionally, we compared the total antioxidant activity in both the cell-free and cellular systems. Betalain contribution to antioxidant activity was also determined using post-column derivatization and it was found that in the case of red beetroot it is about 50%. Photometric measurements are recommended for a simple and inexpensive analysis of the total betacyanin and betaxanthin content. Liquid chromatography techniques produced more precise information on phytochemical composition in the tested samples. The combination of liquid chromatography with high-resolution mass spectrometry produced the largest amount of quantitative and qualitative data; in beetroot samples sixty-four phytochemicals have been identified therefore, this approach is recommended for more detailed metabolomics studies.

Analysis of volatile compound changes in fried shallot (Allium cepa L. var. aggregatum) oil at different frying temperatures by GC-MS, OAV, and multivariate analysis

Flavor is a key attribute of fried oil that shows a critical correlation with temperature. Therefore, selecting the appropriate temperature is important in preparing fried shallot oil (FSO). Volatile compounds from five different FSOs were identified and comparatively studied using gas chromatography-mass spectrometry (GC-MS) coupled with multivariate data analysis, including principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). GC-MS results identified a total of 93 volatiles, among which aldehydes, alcohols, pyrazines, and sulfur-containing compounds were the major compounds. Eighteen compounds had odor active values (OAV) >1. Among the compounds, hexanal, (E)-2-heptenal, (E)-2-octenal, dipropyl disulfide, 2-ethyl-3,5-dimethylpyrazine, and 1-octen-3-ol were important to the overall aroma profile of FSOs. In the PCA model, all the detected FSOs were divided into three clusters, which were assigned as cluster A (FSO5), B (FSO4), and C (the rest FSOs). Multivariate data analyses revealed that nonanal, 2-ethyl-5-methylpyrazine, (E,E)-2,4-decadienal, (E)-2-heptenal, and hexanal contributed positively to the classification of different FSOs. GC-MS coupled with multivariate data analysis could be used as a convenient and efficient analytical method to classify raw materials.

Comparative Metabolomics Profiling of Polyphenols, Nutrients and Antioxidant Activities of Two Red Onion (Allium cepa L.) Cultivars

Onion is among the most widely cultivated and consumed economic crops. Onions are an excellent dietary source of polyphenols and nutrients. However, onions phytonutrient compositions vary with cultivars and growing locations. Therefore, the present study involved the evaluation of polyphenol, nutritional composition (proteins, nitrogen, and minerals), sugars, pyruvate, antioxidant, and α-amylase inhibition activities of red onion cultivars, sweet Italian, and honeysuckle grown in California and Texas, respectively. The total flavonoid for honeysuckle and sweet Italian was 449 and 345 μg/g FW, respectively. The total anthocyanin for honeysuckle onion was 103 μg/g FW, while for sweet Italian onion was 86 μg/g FW. Cyanidin-3-(6”-malonoylglucoside) and cyanidin-3-(6”-malonoyl-laminaribioside) were the major components in both the cultivars. The pungency of red onions in honeysuckle ranged between 4.9 and 7.9 μmoL/mL, whereas in sweet Italian onion ranged from 8.3 to 10 μmoL/mL. The principal component analysis was applied to determine the most important variables that separate the cultivars of red onion. Overall results indicated that total flavonoids, total phenolic content, total anthocyanins, protein, and calories for honeysuckle onions were higher than the sweet Italian onions. These results could provide information about high quality and adding value to functional food due to the phytochemicals and nutritional composition of red onions.

Effect of pretreatment on bioactive compounds in wild rocket juice

The aim of the study was to determine the effect of pretreatment with hot water or steaming on glucosinolates, polyphenols contents and antioxidant capacity in obtained raw juices. Moreover, in vitro cytotoxic activity of the raw juice to the cells derived from the gastrointestinal tract, including the small intestine (IEC-6 cell line), colon (Caco-2 cell line) and the liver (HepG2 cell line) were also investigated. The dominant glucosinolates in the wild rocket leaves were glucoraphanin (36%) and dimeric 4-mercaptobutyl (30%), followed by glucosativin and glucoerucin, 11% per each. Glucothiobeinin (6%), glucobrassicin (1%), 4-methoxyglucobrassicin (1%) and two unidentified compounds (4%) were also detected in rocket leaves. In terms of phenolic compounds, quercetin constituted the majority (55%) and the rest composed of hydroxycinnamic acids. In raw juices produced from steamed, pretreatment with hot water and untreated (control) leaves, glucosinolate contents were lower about 21%, 37% and 53%, respectively, than their levels in the raw material. The highest content of polyphenols among the juices tested (45.4 mg/100 g fresh weight) and antioxidant capacity (5.8 µmol Trolox/1 g f.w.) was recorded in the raw juice from pretreated leaves with hot water. The wild rocket raw juice concentrations responsible for a 50% reduction in Caco-2 and HepG2 cell viability were estimated at 1.87 ± 0.08 mg/mL and 3.54 ± 0.29 mg/mL. The viability of the IEC-6 cells was reduced by only 19.04%, at the maximum concentration (3.6 mg/mL) of the raw juice.