α-Dicarbonyl compounds in food products: Comprehensively understanding their occurrence,analysis, and control

α-Dicarbonyl compounds (α-DCs) are readily produced during the heating and storage of foods, mainly through the Maillard reaction, caramelization, lipid-peroxidation, and enzymatic reaction. They contribute to both the organoleptic properties (i.e., aroma, taste, and color) and deterioration of foods and are potential indicators of food quality. α-DCs are also important precursors to hazardous substances, such as acrylamide, furan, advanced lipoxidation end products, and advanced glycation end products, which are genotoxic, neurotoxic, and linked to several diseases. Recent studies have indicated that dietary α-DCs can elevate plasma α-DC levels and lead to “dicarbonyl stress.” To accurately assess their health risks, quantifying α-DCs in food products is crucial. Considering their low volatility, inability to absorb ultraviolet light, and high reactivity, the analysis of α-DCs in complex food systems is a challenge. In this review, we comprehensively cover the development of scientific approaches, from extraction, enrichment, and derivatization, to sophisticated detection techniques, which are necessary for quantifying α-DCs in different foods. Exposure to α-DCs is inevitable because they exist in most foods. Recently, novel strategies for reducing α-DC levels in foods have become a hot research topic. These strategies include the use of new processing technologies, formula modification, and supplementation with α-DC scavengers (e.g., phenolic compounds). For each strategy, it is important to consider the potential mechanisms underlying the formation and removal of process contaminants. Future studies are needed to develop techniques to control α-DC formation during food processing, and standardized approaches are needed to quantify and compare α-DCs in different foods.     

Simultaneous separation and determination of sugars,ascorbic acid and furanic compounds by HPLC—dual detection

An HPLC method was developed for the simultaneous separation and determination of sugars, ascorbic acid, 5-HMF (5-hydroxymethylfurfural), furfural and four other furanic compounds as the possible degradation products of sugars and ascorbic acid on heating and by Maillard reaction. Sucrose, glucose, fructose, ascorbic acid, dehydroascorbic acid, 5-HMF, furfural, DMHF (2,5-dimethyl-4-hydroxy-3(2H)-furanone), 2-furoic acid, 2-acetylfuran and furfuryl alcohol were separated on an Aminex HPX-87H column (300×7.8 mm). The mobile phase consisted of acetonitrile and 0.005 mol l⁻¹ sulfuric acid aqueous solution (16:84, v/v). Two detectors, a refractive index detector and a photodiode array detector, were used to detect these compounds. Several fruit juice and drink samples were analyzed using this HPLC method. For alcoholic beverages, the content of alcohol was also simultaneously determined by refractive index detector.     

Perfluorinated compounds in fish and blood of anglers at Lake Möhne, Sauerland area, Germany

Perfluorinated compounds (PFCs) were measured in fish samples and blood plasma of anglers in a cross-sectional study at Lake Mo?hne, Sauerland area, Germany. Human plasma and drinking water samples were analyzed by solid phase extraction, high-performance liquid chromatography (HPLC), and tandem mass spectrometry (MS/MS). PFCs in fish fillet were measured by ion pair extraction followed by HPLC and MS/MS. PFOS concentrations in 44 fish samples of Lake Mo?hne ranged between 4.5 and 150 ng/g. The highest median PFOS concentrations have been observed in perches (median: 96 ng/g) and eels (77 ng/g), followed by pikes (37 ng/g), whitefish (34 ng/g), and roaches (6.1 ng/g). In contrast, in a food surveillance program only 11% of fishes at retail sale contained PFOS at detectable concentrations. One hundred five anglers (99 men, 6 women; 14-88 years old; median 50.6 years) participated in the human biomonitoring study. PFOS concentrations in blood plasma ranged from 1.1 to 650 μg/L (PFOA: 2.1-170 μg/L; PFHxS: 0.4-17 μg/L; LOD: 0.1 μg/L). A distinct dose-dependent relationship between fish consumption and internal exposure to PFOS was observed. PFOS concentrations in blood plasma of anglers consuming fish 2-3 times per month were 7 times higher compared to those without any fish consumption from Lake Mo?hne. The study results strongly suggest that human internal exposure to PFC is distinctly increased by consumption of fish from PFC-contaminated sites.     

Two experts,three opinions: volatile organic compounds’ testing methods and regulative systems

As a result of the implementation of the CE-marking in the European Union, the testing method as defined in prEN 16516 is about to become the new volatile organic compounds (VOC) testing standard and replace a multitude of testing methods and regulative systems in Europe that assess the existence of VOC in building materials, including wood-based materials. The aim of this study is, first, to compile expert positions regarding testing methods and regulative systems for VOC in wood-based materials, and second, to examine the suitability of using an Argument-Delphi approach to point out consent or dissent regarding testing methods for VOC. A systematic content analysis of initial interviews with 13 experts produced 130 arguments which were subscribed to 13 categories, resulting in 6 potential positions of which 5 were actively taken by experts. While the second step was undertaken as a cross verification of the analysis, the experts were asked to choose a final position as a last step. It was observed that several experts changed their initial position to testing methods and regulative systems for VOC, but still without a consensus arising within the expert panel. Hence, the results of the study reveal that no verifiable consent exists within the group of experts—neither concerning testing methods, nor regulative systems. The Argument-Delphi approach applied constitutes a useful method in pointing out dissent between the experts towards a legal requirement like a European standard.     

Proteolysis, volatile compounds, and sensory evaluation in Hispánico cheese manufactured with the addition of a thermophilic adjunct culture, nisin, and calcium alginate-nisin microparticles

Nisin, free or incorporated in calcium alginate microparticles, was added to pasteurized milk (80% cows' and 20% ewes' milk) used for the manufacture of Hispánico cheese with a mesophilic starter and a thermophilic adjunct culture of high aminopeptidase activity. Addition of nisin incorporated in microparticles promoted early lysis of thermophilic adjunct culture bacteria. Extracellular aminopeptidase activity in 1-d-old cheese made with both thermophilic adjunct culture and nisin incorporated in microparticles was 1.8-fold higher than in cheese made with thermophilic adjunct culture and free nisin and 2.0-fold higher than in cheese made only with thermophilic adjunct culture without any addition of nisin. Addition of nisin, free or incorporated in microparticles, did not influence cheese proteolysis measured using hydrophilic or hydrophobic peptides, o-phthaldialdehyde ripening index, or free amino acids. Moreover, a total of 37 volatile compounds were identified in the volatile fraction of Hispánico cheese, using a dynamic headspace technique with a purge and trap system followed by a gas chromatography mass spectrometry analysis. The volatile compound profile was not influenced by nisin addition, either free or incorporated in microparticles, but addition of thermophilic adjunct culture enhanced the formation of 2-butanone, diacetyl, 2,3-pentanedione and acetoin and improved the flavor quality (sensory panel) of cheese.     

Assessment of Indigo (Polygonum tinctorium Ait.) water extracts’ bioactive compounds,and their antioxidant and antiproliferative activities

There are a few investigations on Indigo (Polygonum tinctorium Ait.), as a medicinal plant. Therefore, the aim of this study was to assess the contents of bioactive compounds, antioxidant and antiproliferative activities and to compare with another medicinal plant Prolipid. It was found that the bioactive compounds from different parts of Indigo water extracts varied (P < 0.05): polyphenols and flavonoids were significantly higher in Prolipid, flavanols in Indigo seeds, and vitamin C similar in Indigo leaves and Prolipid. The antioxidant activity by ABTS, FRAP, CUPRAC and DPPH assays was significantly different (P < 0.05): the highest in Prolipid, following by Indigo mature leaves. DPPH kinetic measurements compared, distinguished and discriminated the antiradical activity among Indigo and Prolipid water extracts by multivariate analysis. The interaction between polyphenol extracts of Indigo mature leaves and BSA showed that Indigo has a strong ability, as other medicinal plants, to quench the intrinsic fluorescence of BSA by forming complexes. In conclusion, for the first time Indigo mature leaves were analyzed and compared with widely consumed Prolipid. The relatively high content of bioactive compounds, positive antioxidant, fluorescence and antiproliferative properties of Indigo justify the use of this plant as a new source of valuable antioxidants.     

Measurements of atmospheric carboxylic acids and carbonyl compounds in São Paulo City, Brazil

Winter atmospheric measurements of gaseous lower carbonyl and carboxylic acids were carried out simultaneously (in 1999) at two distinct urban sites located in the city of S?o Paulo, Brazil. The greater metropolitan area of S?o Paulo is the largest industrialized region of Latin America and has a highly polluted atmosphere. It has an unconventional mix of vehicle types in that a variety of gasoline blends, including oxygenated ones, are used. Mixing ratios of formic and acetic acids ranged, respectively, from 0.6 to 19.4 and from 0.1 to 10.6 ppbv in one of the sites studied and from 1.4 to 18.4 and from 0.4 to 6.7 ppbv in the other site. High values of formic to acetic ratios were found, especially in the latter site (average = 4.3), suggesting that photochemical production was the predominant source of the formic and acetic acid during the afternoon. Differing from the acids, levels of carbonyls were similar at both sites. Higher average mixing ratios of acetaldehyde and formaldehyde were found in the morning (18.9 and 17.2 ppbv) and gradually decreased from midday (9.5 and 11.8 ppbv) to evening (7.2 and 10.2 ppbv). In the morning, vehicular direct emission seemed to be the main primary source of formaldehyde and acetaldehyde, whereas at midday and evening these compounds appeared to be mainly formed by photochemistry. Secondary photochemical production of organic acids and aldehydes (rather than primary emissions from vehicles) was shown to be more important in S?o Paulo's atmosphere from midday to evening, particularly on days with strong solar radiation.     

Sucuk and pastırma: Microbiological changes and formation of volatile compounds

There is an increasing interest in traditional foods in Turkey like other countries. Sucuk, dry-fermented sausage, and past?rma, a type of dry-cured meat product, are traditional Turkish meat products that are widely consumed. Sucuk is air-dried and neither smoked nor ripened by mold. In spite of increasing use of starter culture in production of sucuk in the industry, traditionally produced sucuk is generally preferred by the consumers because of its sensory characteristics. Past?rma is traditionally processed under natural conditions where air temperature and relative humidity depend on climate and weather conditions. Past?rma differs from other raw cured meat products made from whole pieces of meat in terms of manufacturing process, ingredients, microbial properties and flavor. In this study, microbiological changes and formation of volatile compounds in sucuk and past?rma were reviewed.     

Eating quality of raw carrots––correlations between flavour compounds,sensory profiling analysis and consumer liking test

Sensory profiling, analysis of aroma, sugar and dry matter, as well as consumer liking test were used to characterise the quality of six carrot cultivars, grown at two locations in Denmark. The carrot samples were examined at harvest, and after three months of cold storage. Carrot cultivar had an effect on most sensory and flavour compound variables, due particularly to the influence of one cultivar; and also location influenced carrot quality. Storage of carrots was characterised by an increase of a range of aroma components, but the changes in flavour compounds were not correspondingly observed by the sensory analysis. By Partial Least Squares Regression (PLSR) two thirds of the flavour compound variables was found to correlate significantly with one or more of the nine sensory attributes; and all of the sensory attributes were significantly correlated with one or more of the consumer liking test variables bitterness, sweetness and liking.     

Bioactive compounds and health benefits of exotic tropical red–black berries

Tropical countries produce a large amount of native and exotic fruit species which are potentially interested in the food industry. The nutritional and therapeutic values in this fruits are mainly due to the presence of bioactive compounds, especially polyphenols. The anthocyanins belong to the flavonoid family and represent a group of pigments responsible for most of the colors in fruits, leaves, flowers, stems and roots of plants. Several investigations have focused on the health benefits of consumption of red–black fruit, claiming these as natural sources of bioactive compounds with highly promising antioxidant and anti-inflammatory characteristics. Furthermore, the consumption of red–black berries brings a positive impact on several chronic conditions, such as obesity, diabetes, cancer, cardiovascular and neurodegenerative diseases. This article summarizes the foremost bioactive compounds and the health properties of exotic tropical red–black berries, specifically Euterpe oleracea, Eugenia uniflora, Myrciaria cauliflora, Myrciaria dubia, Syzygium cumini.     

Are PFCAs bioaccumulative? A critical review and comparison with regulatory criteria and persistent lipophilic compounds

Perfluorinated acids, including perfluorinated carboxylates (PFCAs), and perfluorinated sulfonates (PFASs), are environmentally persistent and have been detected in a variety of wildlife across the globe. The most commonly detected PFAS, perfluorooctane sulfonate (PFOS), has been classified as a persistent and bioaccumulative substance. Similarities in chemical structure and environmental behavior of PFOS and the PFCAs that have been detected in wildlife have generated concerns about the bioaccumulation potential of PFCAs. Differences between partitioning behavior of perfluorinated acids and persistent lipophilic compounds complicate the understanding of PFCA bioaccumulation and the subsequent classification of the bioaccumulation potential of PFCAs according to existing regulatory criteria. Based on available research on the bioaccumulation of perfluorinated acids, five key points are highlighted in this review: (1) bioconcentration and bioaccumulation of perfluorinated acids are directly related to the length of each compound's fluorinated carbon chain; (2) PFASs are more bioaccumulative than PFCAs of the same fluorinated carbon chain length; (3) PFCAs with seven fluorinated carbons or less (perfluorooctanoate (PFO) and shorter PFCAs) are not considered bioaccumulative according to the range of promulgated bioaccumulation,"B", regulatory criteria of 1000-5000 L/kg; (4) PFCAs with seven fluorinated carbons or less have low biomagnification potential in food webs, and (5) more research is necessary to fully characterize the bioaccumulation potential of PFCAs with longer fluorinated carbon chains (>7 fluorinated carbons), as PFCAs with longer fluorinated carbon chains may exhibit partitioning behavior similar to or greater than PFOS. The bioaccumulation potential of perfluorinated acids with seven fluorinated carbons or less appears to be several orders of magnitude lower than "legacy" persistent lipophilic compounds classified as bioaccumulative. Thus, although many PFCAs are environmentally persistent and can be present at detectable concentrations in wildlife, it is clear that PFCAs with seven fluorinated carbons or less (including PFO) are not bioaccumulative according to regulatory criteria.     

Extraction of phenolic compounds from grapes and their pomace using β-cyclodextrin

Use of aqueous cyclodextrins (CD) for recovery of selected bioactive phenolic compounds from grapes and their pomace was evaluated. When α, β and γ forms of CD were compared, β-CD was the most effective in recovering stilbenes, flavonols, and flavan-3-ols from grape pomace. The maximum quantified phenolics were obtained from the powder and the slurry of grape pomace when extracted with 2.5% (w/v) aqueous β-CD solutions at 60 °C for 12–24 h. With β-CD, total quantified phenolics obtained from the dry powder were 123 mg/100 g (DW) while from the slurry, they were 35.8 mg/100 g (FW). Incorporation of β-CD to grape mash prior to pressing for juice enhanced the recovery of phenolics in juice. Incorporation of β-CD was more effective in recovering flavan-3-ols than flavonols. Aqueous CD can effectively be used in recovering phenolics from by-products of fruit processing and therefore for functional foods and nutraceutical applications.     

Identification and quantification of phenolic compounds from pomegranate (Punica granatum L.) peel,mesocarp, aril and differently produced juices by HPLC-DAD–ESI/MS

Phenolic compounds were extracted from pomegranate (Punica granatum L.) peel, mesocarp and arils. Extracts and juices were characterised by HPLC-DAD–ESI/MSⁿ. In total, 48 compounds were detected, among which 9 anthocyanins, 2 gallotannins, 22 ellagitannins, 2 gallagyl esters, 4 hydroxybenzoic acids, 7 hydroxycinnamic acids and 1 dihydroflavonol were identified based on their UV spectra and fragmentation patterns in collision-induced dissociation experiments. To the best of our knowledge, cyanidin–pentoside–hexoside, valoneic acid bilactone, brevifolin carboxylic acid, vanillic acid 4-glucoside and dihydrokaempferol-hexoside are reported for the first time in pomegranate fruits. Furthermore, punicalagin and pedunculagin I were isolated by preparative HPLC and used for quantification purposes. The ellagitannins were found to be the predominant phenolics in all samples investigated, among them punicalagin ranging from 11 to 20 g per kilogram dry matter of mesocarp and peel as well as 4–565 mg/L in the juices. The isolated compounds, extracts and juices were also assessed by the TEAC, FRAP and Folin–Ciocalteu assays revealing high correlation (R² = 0.9995) of the TEAC and FRAP values, but also with total phenolic contents as determined by the Folin–Ciocalteu assay and by HPLC. Selection of raw materials, i.e. co-extraction of arils and peel, and pressure, respectively, markedly affected the profiles and contents of phenolics in the pomegranate juices, underlining the necessity to optimise these parameters for obtaining products with well-defined functional properties.     

Comparison on aroma compounds in Chinese soy sauce and strong aroma type liquors by gas chromatography–olfactometry,chemical quantitative and odor activity values analysis

In order to elucidate the differences on aroma compounds in Chinese liquors with different aroma styles and the reasons, aroma compounds of Xijiu in soy sauce aroma and strong aroma type were investigated in the research. By gas chromatography–olfactometry (GC–O), aroma compounds in Chinese liquor were chosen for quantitative and odor activity value (OAV) analysis. Ethyl hexanoate, butanoic acid, 3-methylbutanoic acid, hexanoic acid and dimethyl trisulfide were considered to be the most powerful odorants in both liquor samples (aroma intensity ≥3.5) by GC–O. As important aroma compounds (OAV ≥10) in the liquors, ethyl propanoate, ethyl 2-methylpropanoate and 1-propanol were considered with much higher OAVs in soy sauce aroma type liquor, while OAVs of ethyl pentanoate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, ethyl lactate, hexyl acetate, butyl hexanoate, hexyl hexanoate and hexanoic acid were far lower in strong aroma type liquor. The OAV of ethyl hexanoate in strong aroma type liquor exceeded 50,000, which explained the reason why strong aroma liquor was considered with prominent fruity aroma. The odor differences between the liquors were mainly caused by the manufacturing practices.     

Can plant phenolic compounds reduce Fusarium growth and mycotoxin production in cereals?

ABSTRACT

To assess the in vitro activity of three phenolic acids (ferulic acid, p-hydroxybenzoic acid, vanillic acid) and two flavonols (quercetin, rutin) on mycelial growth and mycotoxin accumulation of Fusarium graminearum (FG), F. langsethiae (FL) and F. poae (FP), two different approaches were chosen. First, grains from oat varieties were inoculated with a suspension of three FL isolates to determine the influence of phenolic compounds on the accumulation of mycotoxins. The oat variety Zorro showed a tendency for lower accumulation of T-2/HT-2, diacetoxyscirpenol and neosolaniol. Second, a mycelium growth assay was conducted to follow FG, FL and FP growth on cereal based media supplemented with phenolic compounds. Increasing concentrations of ferulic acid substantially inhibited growth of FG and FL, while FP growth was reduced to 57%. In contrast, p-hydroxybenzoic acid, vanillic acid, quercetin, and rutin slightly stimulated mycelium growth. Results about mycotoxin production in cereal based media were less conclusive.     

Two flavanone compounds from litchi (Litchi chinensis Sonn.) seeds,one previously unreported,and appraisal of their α-glucosidase inhibitory activities

Using a bioactivity-guided method, a new and a previously reported flavanone glycoside were isolated from 50% ethanol extract of litchi (Litchi chinensis Sonn.) seeds. Column chromatography using macroporous resin, silica gel and Sephadex LH-20 was applied during the isolation, and the method of PMP derivatisation was performed to investigate the component sugar of the compounds. The structures of the compounds were elucidated by ¹H, ¹³C, and 2D NMR (HMQC, HMBC) spectroscopy and HR-ESIMS. Compound 1 was identified as (2R)-naringenin-7-O-(3-O-α-l-rhamnopyranosyl-β-d-glucopyranoside), a new, natural product that had been synthesised previously. Compound 2 was (2S)-pinocembrin-7-O-(6-O-α-l-rhamnopyranosyl-β-d-glucopyranoside). The two isolated compounds showed activity in the α-glucosidase inhibition assay.     

Phenolic compounds’ characterization of Artemisia rutifolia spreng from Pakistani flora and their relationships with antioxidant and antimicrobial attributes

Artemisia rutifolia (Asteraceae) had been used in traditional medicines for the treatment of different ailments. In the current study, an effort was made to explore the phenolic composition, antioxidant, and antimicrobial activities of different solvent extracts obtained from A. rutifolia leaves. The reverse-phase high-performance liquid chromatographic (RP-HPLC) analysis revealed the higher extent of polyphenolic compounds (i.e., gallic acid, caffeic acid, chlorogenic acid, syringic acid, sinapic acid, p-coumaric acid, m-coumaric acid, ferulic acid, vanillic acid, myricetin, and quercetin) in methanol extract. Methanol extract consistently showed the highest total phenolic contents (98 ± 2 µg GAE/mg of plant extract), total flavonoid contents (28 ± 0.0 µg QE/mg of plant extract), antimicrobial activity, free radical (DPPH) scavenging (IC₅₀ = 39 µg/mL) activity, and reducing power (18.3 ± 0.2 mg GAE/g of plant extract) followed by those of chloroform and hexane extracts, respectively. The current study concluded that extracts of A. rutifolia are novel natural source of antioxidative and antimicrobial agents for the treatment of oxidative stress-related disorders and microbial infections.