Improvement of Robusta coffee aroma with l-leucine powder.

BACKGROUND: l-Leucine powder (LP) was added to green Robusta coffee beans in order to reduce the difference in flavour between Robusta and Arabica coffee. l-Leucine was selected as an additive based on the Maillard reaction. The pre-treatment method conducted in this study was a short soaking (M1) or spraying procedure (M2), then LP was added at varying levels up to 3% (w/w, 30 g kg-1 ). All samples were roasted (240 °C for 15 min) and extracted using an espresso machine. Volatile compounds were analysed by solid-phase microextraction-gas chromatography-mass selective detection. RESULTS: Thirty volatile compounds (six pyrroles, eight pyrazines, three phenols, nine furans, two ketones, two aldehydes) were analysed. In 15 coffee samples, the levels of total volatile compounds (based on peak area ratios) ranged from 8.9 (M1-1) to 15. Non-treated Robusta had higher levels of bitter aroma compounds than Arabica coffee, and Robusta coffee had lower levels of bitter aroma compounds when pre-treated with LP. The sum of bitter volatiles (phenols, pyrroles, pyrazines) was lowest in M1-5 (3% LP), M2-1 (1% LP; both dried at 50 °C for 15 min) and M2-7 (3% LP, dried at 70 °C for 15 min) compared with non-treated Robusta (P < 0.05). CONCLUSION: From the results of this study it can be shown that pre-treatment with LP can improve the flavour of Robusta. © 2023 Society of Chemical Industry.

Analysis of furan and monosaccharides in various coffee beans.

The furan levels in commercial coffee product samples (17 instant coffees, 12 mixed coffee, 8 canned coffee) were 49-2155, 10-201 and 15-209 ng/g, respectively. Since thermal degradation/rearrangement of carbohydrates is the main source of furan, the concentrations of furan and monosaccharides (mannose, rhamnose, glucose, galactose and arabinose) were analysed in 26 green and roasted coffee bean (Coffea arabica) varieties. In coffee beans, furan levels ranged from 4.71 (Bourbon Cerrado, Brazil) to 8.63 mg/kg (San Vicente, Honduras). Galactose was the main monosaccharide in green beans, followed by arabinose, glucose, mannose and rhamnose, on average. Roasting decreased the glucose content by about 81%, and arabinose decreased about 27% in all coffee beans. Glucose decreased the greatest after roasting and is thereby considered the major contributor to the formation of furan.

Validation of analytical method for furan determination in eight food matrices and its levels in various foods.

In this study, an automated solid-phase microextraction coupled with gas chromatography and mass spectrometry method was developed and validated for the determination of furan in eight matrices including ham, milk, apple juice, rice porridge, peanut butter, flatfish, tuna (canned) and seaweed. The calibration curves were highly linear (r2  > 0.990) and the limit of detection and limit of quantification ranged from 0.01-0.02 and 0.04-0.06 ng/g, respectively. The recovery ranged from 77.81-111.47%. The validated method was used to analyse the furan levels in 120 foods. The highest levels of furan were detected in black tea (172.05 ng/g) and red ginseng extract (89.27 ng/g). Whelk (canned) contained a high furan content (21.34 ng/g) among the seafood samples.

Organic acids as a freshness indicator for tofu (soybean curd).

The aim of this study was to evaluate organic acids as potential indicators of tofu freshness. To achieve this, relationships between organic acids concentrations and the growth of microorganisms in fresh tofu were investigated. The levels of microorganisms (total bacterial count) and organic acids (phytic acid, oxalic acid, citric acid, lactic acid, formic acid and acetic acid) were analyzed in tofu (packed and unpacked) every 3 days during 15 days of storage at different temperatures (4, 10, and 25 °C). Organic acids were analyzed by high performance liquid chromatography and microbial analysis was conducted by plate counting method. The levels of oxalic acid, citric acid and formic acid decreased significantly during the storage period, while the levels of lactic acid and acetic acid increased significantly when stored at 10 °C. The acetic, lactic and formic acids showed significant correlation to the levels of microorganisms in packed tofu, suggesting the use of these organic acids as potential freshness quality indicators of tofu. Current study demonstrated the effective way of predicting freshness of tofu by utilizing organic acid analysis, as opposed to traditional method relying on microbial count.

Volatile and non-volatile compounds in green tea affected in harvesting time and their correlation to consumer preference.

Current study was designed to find out how tea harvesting time affects the volatile and non-volatile compounds profiles of green tea. In addition, correlation of instrumental volatile and non-volatile compounds analyses to consumer perception were analyzed. Overall, earlier harvested green tea had stronger antioxidant capacity (~61.0%) due to the polyphenolic compounds from catechin (23,164 mg/L), in comparison to later harvested green teas (11,961 mg/L). However, high catechin content in green tea influenced negatively the consumer likings of green tea, due to high bitterness (27.6%) and astringency (13.4%). Volatile compounds drive consumer liking of green tea products were also identified, that included linalool, 2,3-methyl butanal, 2-heptanone, (E,E)-3,5-Octadien-2-one. Finding from current study are useful for green tea industry as it provide the difference in physiochemical properties of green tea harvested at different intervals.

Effects of pan- and air fryer-roasting on volatile and umami compounds and antioxidant activity of dried laver (Porphyra dentata).

This study aimed to investigate the impact of pan- and air fryer-roasting on the volatiles, umami compounds, antioxidant activity, and sensory attributes of dried laver (Porphyra dentata). To assess the influence of time and temperature, pan-roasting was conducted at temperatures of 250, 300, and 350 °C for 5, 10, and 15 s, respectively. For air fryer-roasting, dried laver was roasted at 160, 170, and 180 °C for 2, 4, and 6 min, respectively. In both roasting methods, the levels of 1,5-octadien-3-ol and 1-octen-3-ol significantly decreased (p < 0.05) with increased time and temperature. The Equivalent Umami Concentration ranged from 94.89 to 518.09 g MSG/100 g. The antioxidant activity significantly increased (p < 0.05) with higher roasting temperatures and longer durations, whereas pigment content significantly decreased. The browning index increased by 64% and 43% for the pan and air frying methods, respectively. The samples pan-roasted at 300 °C for 15 s obtained the highest sensory scores.

Analysis of physicochemical properties of nut-based milk and sweetened condensed milk alternatives.

This study analyzed the physicochemical properties of nut-based milk and sweetened condensed milk (SCM) alternatives. Four types of nuts (almonds, cashews, hazelnuts, and walnuts) were roasted at 140 °C for 15 min, followed by the preparation and analysis of milk and SCM alternatives. During the production of SCM by heating with adding sugar, the pH, moisture, and L* decreased, while the carbohydrates, viscosity, and browning index increased significantly (p < 0.05). Oleic acid, linoleic acid, and linolenic acid contents were comparable among all samples (p > 0.05). Volatile compounds were analyzed using HS-SPME-GC-MS to determine changes due to roasting and heating, and a total of 54 volatile compounds were identified. These findings to show the importance of the physicochemical characteristics of milk and SCM alternatives, provide practical information for the development of improved-quality dairy alternatives.

Effects of ultrasound on the structural, physicochemical, and emulsifying properties of aquafaba extracted from various legumes.

This study investigated the effect of ultrasound (20-60 min, 40 kHz, 280 W) on the structural, physicochemical, and emulsifying properties of aquafaba extracted from various legumes (chickpea [CH], yellow soybean [YSB], black soybean [BSB], small black bean [SBB]). The hydrophobic amino acids and protein secondary structures (α-helix, random coil) significantly increased with sonication time (p < 0.05). The particle size of aquafaba was reduced by ultrasound (p < 0.05). A total of 27 volatile compounds were identified. Most volatiles increased with sonication time, and beany flavor was lowest in CH and SBB. The EAI, ESI, adsorbed proteins, and zeta-potential increased, while emulsion droplet size decreased in all legumes by ultrasound. The overall emulsifying properties were the highest in SBB sonicated for 40 min. This study discusses the applicability of ultrasound to aquafaba and provides insights into the functional properties and potential of aquafaba as a plant-based natural emulsifier.

Analysis of volatile compounds and 5-hydroxymethylfurfural in fried chicken breast produced by air and deep-fat frying.

Two samples, simple-battered chicken (SBC) and normal-battered chicken (NBC), with different batters were deep-fat fried at various conditions and volatile compounds and 5-hydroxymethylfurfural (5-HMF) was analysed. The moisture content of the air-fried samples was significantly higher than that of the deep-fat fried samples in the same batter samples. A total of 72 volatile compounds (8 aldehydes, 15 monoterpenes, 12 sesquiterpenes, 2 terpene alcohols, 4 benzenes, 13 pyrazines, 2 pyridines, 6 furans, 5 alcohols, 2 pyrroles, and 3 others) were detected in fried chicken breast, and air-fried SBC possessed the highest total amount of volatile compounds. Furthermore, 5-HMF was exclusively detected in NBC samples; in particular, 1.27 ± 0.06 and 0.41 ± 0.02 µg/mL were detected in deep- and air-fried NBC, respectively. This study indicates the potential of air frying to reduce the formation of 5-HMF while maintaining quality characteristics, suggesting the need for further study on other hazardous compounds.

Analysis of volatile compounds and α-dicarbonyl compounds in Arabica coffee soaked with various organic acids.

In this study, volatile compounds and α-dicarbonyl compounds (α-DCs), such as glyoxal (GO), methylglyoxal (MGO), and diacetyl (DA), were analyzed in Arabica coffee prepared from Arabica green coffee beans presoaked in six organic acid solutions. The ratio of volatile compounds in samples was 18.06 to 0.6 (peak area of each peak/peak area of internal standard). Succinic acid pretreated Arabica had the highest concentration of volatile compounds, 128.9% higher than without pretreatment. The level of total α-DCs ranged from 12.90 to 100.32 µg/mL. Detected levels of GO, MGO, and DA ranged from 0.81 to 7.74, from 18.53 to 89.08, and from 0.43 to 6.74 µg/mL, respectively. Organic acid pretreatment increased the amounts of volatile compounds and lowered the concentrations of α-DCs compared to without pretreatment. The results obtained in this study would be useful for increasing the flavor of Arabica coffee and decreasing α-DCs. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01592-2.

Analysis of 8-oxooctanoate, 9-oxononanoate, fatty acids, oxidative stability, and iodine value during deep-frying of French fries in edible oils blended with palm oil.

Four blended oils including palm + corn oil (PC), palm + grapeseed oil (PG), corn + grapeseed oil (CG), and palm + corn + grapeseed oil (PCG) were used as frying media. The 8-oxo and 9-oxo content, fatty acid composition, oxidative stability index, and iodine value of samples (n = 42) were analyzed. As the frying cycles increased, the content of 8-oxo and 9-oxo also increased significantly (p < 0.05) and showed the highest content of 965.56 ± 0.706 µg/g in 100 frying cycles of PCG. After 20-40 frying cycles in CG, the amount of palmitic, stearic, oleic and linoleic acid increased up to 15.5% (p < 0.05). The oxidative stability of palm oil was the highest at 16.76-18.33 h (p < 0.05). The iodine value of grapeseed oil was the highest at 144.96 ± 2.569-153.64 ± 2.233 g iodine/100 g oil (p < 0.05). Among the examined oils, PC was the most suitable alternative to palm oil.

Analysis of volatile compounds, betaine, and antioxidant effect in goji berry (Lycium barbarum L.) powder extracted by various drying methods and extraction solvents.

Goji berry (Lycium barbarum L.), a deciduous solanaceous shrub, were subjected to extraction using five solvents (water, 50% and 70% ethanol, and 50% and 70% methanol) and dried using two methods: freeze drying (FD) and spray drying (SD). To investigate the chemical properties of these various goji berry powders, an examination was conducted on the content of volatile compounds, betaine, antioxidant effect, total phenolic content (TPC), and total flavonoid compounds (TFC) (p < 0.05). The total volatile compound content was highest in SD powder with 50% ethanol extract, showing a 66.7% increase over the control. The betaine content was in the range of 9.25-31.9 mg/g dry weight, and it exhibited a significant increase with higher water concentration in the extraction solvent. Betaine, total phenolic compounds and total flavonoid compounds showed a significant increase in the sequence of SD followed by FD (p < 0.05). Overall, the SD sample showed superior benefits when evaluating volatile compounds, betaine, and antioxidant effect. SD was more suitable for drying goji berry, as it retains its appearance and biological activity.

Analytical methods, risk assessment, and mitigation strategies for furan in processed foods in various countries.

This article provides an overview of analytical methods for measuring furan levels in food. Given the potential carcinogenicity of furans in humans, several studies have focused on assessing furan levels in various food products. In this review, we specifically examine furan levels in foods that are central to regional culinary traditions and summarize the results of country-specific risk assessments. Consequently, we have identified foods that contribute significantly to dietary furan exposure in each region. Coffee and baby foods, regardless of region, emerged as the primary sources of furan intake among adults and infants, respectively. Several previous studies have been conducted to develop various mitigation strategies aimed at reducing exposure to furan through food intake. Therefore, in this paper, we categorize effective mitigation strategies into two main groups: alterations to processing conditions and the addition or removal of food additives and ingredients.

Analysis of oxidation products and toxic compounds in edible and blended oil during the deep-frying of french fries.

This study sought to analyze the oxidative products [acid value (AV), free fatty acids (FFA), conjugated dienoic acid (CDA), p-anisidine value (p-AV), antioxidant-prooxidant balance (APB) value] and toxic compounds [3-monochloropropane diol (3-MCPD), glycidyl ester (GE)] in edible oils after deep-frying. The deep-frying edible oils evaluated herein included soybean oil (S), palm oil (P), canola oil (C), grape seed oil (G), and a 1:1 blend (SC, SG, PC, PG, and CG). As frying time increased, the level of AV in PC, total FFA contents in CG, and p-AV in CG significantly increased up to 200%, 45.5%, and 410.5%, respectively (p < 0.05). The levels of 3-MCPD, and GE were 0.81-6.28 µg/mL and 0.14-2.84 µg/mL, respectively. The levels of 3-MCPD, GE, CDA, and APB changed significantly as frying time increased. Analysis of the correlation between oxidation products and toxic compounds indicated that the contents of 3-MCPD and palmitic acid were positively correlated. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01494-9.

Analysis of 207 residual pesticides in hot pepper powder using LC-MS/MS.

This study investigated the determination of 207 pesticides in hot pepper powder and found patterns of pesticide use by production from five regions, detecting a total of 50 pesticides. The LOD, LOQ and recoveries of pesticides were 0.08-2.53, 0.25-7.60 µg kg-1, and 81.0-132.1%, respectively. The Horrat values ranged from 0.07 to 1.97. A total of 50 residual pesticides were detected in 963 hot pepper powder samples. All residual pesticide levels were below the Korean maximum residue level (MRL) and the %ADI was ≤ 0.001-0.076%. Seven pesticides had a detection rate above 50% (tebuconazole, pyraclostrobin, etofenprox, flonicamid, imidacloprid, carbendazim, and flubendiamide). The region where the most pesticide types were detected was Ham-pyeong with 38 types. Tebuconazole had detection rates of > 90% in all regions. In the PCA results with factor analysis, each region shows patterns of pesticide use. Four regions focus on Aphidoidea control and one region on Colletotrichum acutatum control. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01443-6.

Antibacterial, antioxidant activities of lactic acid bacteria-bioconversioned almond extract.

This study was about bioconversion of almonds by lactic acid bacteria. There are two bacteria used for bioconversion of almond extract: Lactiplantibacillus plantarum ATCC14917 and Lacticaseibacillus rhamnosus GG KCTC5033. Almond extract (AE) was inoculated with L. plantarum or L. rhamnosus GG for 3 days. AE inoculated with L. plantarum (LP-AE) and AE inoculated with L. rhamnosus GG (LR-AE) inhibited the growth of Salmonella Typhimurium and the growth of Yersinia enterocolitica by 30 and 75%, respectively compared to AE. LR-AE inhibited 30% of biofilm formation of S. Typhimurium and Y. enterocolitica compared to AE. Antioxidative activity of LP-AE and LR-AE was determined using the 2,2'-zino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) assay. ABTS radical scavenging activity of AE, LP-AE and LR-AE was 53.50%, 80.39% and 83.57%, respectively. The highest level of total polyphenol (89.72 mg Gallic Acid Equivalent (GAE)/g) and flavonoid (194.56 mg Quercetin Equivalent (QCE)/g) contents was found in LR-AE.

Effect of ultrasound and microwave treatment on the level of volatile compounds, total polyphenols, total flavonoids, and isoflavones in soymilk processed with black soybean (Glycine max (L.) Merr.).

This study analyzed the effect of ultrasound treatment (up to 9 min, 20 kHz, 130 W) on the volatile compounds, total polyphenols, total flavonoids, and isoflavones (daidzein, genistein, daidzin, genistin, and glycitin) in soymilk processed with microwave-roasted (700 W for 270 s) black soybean (Glycine max (L.) Merr.). 1-Hexanol and 1-octen-3-ol, unpleasant soybean flavors, were found to decrease by up to 96.13% and 93.04%, respectively, in ultrasound-treated soymilk compared to the control. 2,3-Diethyl-5-methylpyrazine, a baked flavor, which exhibited the highest odor impact ratio in soymilk processed with microwave-roasted soybean, increased significantly during ultrasound treatment (p < 0.05). The content of total isoflavones, polyphenols, and flavonoids increased (p < 0.05) with the increase in ultrasound treatment time. Spearman's correlation analysis showed that browning was positively correlated (p < 0.01) with total phenols, total furans, total pyrazines, total polyphenols, and total isoflavones. This study discusses the applicability of microwave-roasted soybeans for improving the volatile profile and bioactive compounds in soymilk and provides information on the effects of ultrasound treatment on the volatile compounds, total polyphenols, flavonoids, and isoflavones in soymilk.

Effect of organic acid-soaking and sonication on the formation of volatile compounds and α-dicarbonyl compounds in Robusta coffee.

In this study, the effects of organic acid-soaking (malic, citric, tartaric, and succinic acid) and sonication on the formation of flavor and α-dicarbonyl compounds in Robusta (C. canephora syn. Coffea robusta) green beans were investigated. A total of 20 volatile compounds were identified in Robusta coffee. Furfural and 5-methyl furfural, two dominant volatile compounds in Arabica coffee, increased after organic acid pretreatment. In Robusta coffee processed from 3% malic acid-soaked coffee beans, furfural and 5-methyl furfural increased by 90.99% and 24.92%, respectively, compared to the control. In Robusta coffee processed from 3% malic acid-sonicated (280 W, 1 h) coffee beans, furfural and 5-methyl furfural increased by 236.03% and 114.77%, respectively. α-Dicarbonyls (glyoxal, methylglyoxal, and diacetyl) were significantly (p < 0.05) decreased in all Robusta coffees after organic acid pretreatment. In Robusta coffee processed from coffee beans soaked and sonicated in tartaric acid solution, the α-dicarbonyls decreased by up to 44% and 58%, respectively, compared to the control. This study suggested the pretreatment methods to enhance the flavor substances and reduce the α-DCs in Robusta coffee.

Detection of porcine DNA in Korean processed foods by real-time PCR.

In this study, a commercial DNA extraction kit and a real-time Polymerase Chain Reaction (PCR) kit were applied to detect porcine DNA in Korean processed foods. The specificity, sensitivity, applicability and inter-laboratory reproducibility were evaluated for analytical method validation. We observed no false-positive or false-negative results in the assay, confirming its specificity. The sensitivity of the real-time PCR was expressed as the limit of detection (LOD), which was determined to be 0.005 ng in 35 cycles. In the applicability test, PCR was performed on 12 types of food matrices, and there were no inhibitor effects. An interlaboratory comparison showed no statistically significant (p > 0.05) differences between the results from two laboratories. We analysed 131 samples to determine the presence of porcine DNA for halal certification: 129 samples were negative, and porcine DNA was detected in one sample each of instant noodles and dumpling. The real-time PCR applied in this study is a reliable analytical method to detect porcine DNA in food and can be used easily, quickly and routinely in food facilities.

Synthetic colourants in capsule dietary supplements on the Korean market.

This study developed a rapid and easy analytical method for the simultaneous determination of nine synthetic colourants (SCs) in capsule dietary supplements. Sample pretreatment involved thermal treatment to dissolve gelatin, using the enzymes protease and amylase to prevent the gelation of gelatin and fat-soluble substances removal using petroleum ether. The method was linear (r2 ≥0.999), with LOD of 0.009-0.029 µg/mL and LOQ of 0.42-1.40 µg/g. Recovery ranged from 90.9 to 108.9%. The relative expanded measurement uncertainty ranged from 4.1 to 6.3%. Allura Red AC (R40) and Brilliant Blue FCF (B1) were commonly detected in 20 of the 28 samples. Up to six SCs such as Tartrazine (Y4), Sunset yellow (Y5), Amaranth (R2), Erythrosine B (R3), R40 and B1 were detected in a single sample, ranging from 30.5 to 40.2 µg/g. Total content of SCs in various capsule supplements ranged from 0.3 to 73.7 µg/g.