Phenolic content,antioxidant and physico‐chemical properties of Sardinian monofloral honeys

In this study, fifty‐one monofloral Sardinian honeys from ten various floral origins were screened for their phenolic content, antioxidant activity, colour and electrical conductivity. The total phenolic amounts have been evaluated by Folin–Ciocalteu method, whereas quantification of several phenolic compounds (phenolic acids and flavonoids) has been carried out by HPLC‐DAD technique. The richest sample in phenolic compounds resulted strawberry tree honey with about 40 mg GAE/100 g, as well FRAP test and DPPH˙ test confirm that antioxidant activity of strawberry tree honey extract exceed both honey extracts and synthetic antioxidants like BHA and BHT. Among the studied phenolic compounds a total of five phenolic acids (ferulic, syringic, trans‐cinnamic, chlorogenic and p‐hydroxycinnamic) and nine flavonoids (catechin, kaempferol, rutin, quercetin, luteolin, apigenin, galangin, pinocembrin and pinobanksin) were identified. Our results show good correlations between total polyphenol amount and antioxidant activity and between colour and electrical conductivity.     

Ultrasound-assisted extraction gas chromatography–mass spectrometry analysis of volatile compounds in unifloral thyme honey from Greece

The volatile fraction of unifloral Greek thyme honey was investigated by means of ultrasound-assisted extraction followed by GC–MS analysis. Phenolic compounds were the most abundant, followed by short chain fatty acids. In total, 14 compounds are proposed as potent botanical markers for thyme honey, 12 of which are phenolics. Among them, 3-hydroxy-4-phenyl-2-butanone and 3-hydroxy-1-phenyl-2-butanone were the most important, as their concentration averages more than 35 mg/kg of honey. Significant average proportions were found for 1-phenyl-2,3-butanedione, 3-hydroxy-4-phenyl-3-buten-2-one, 3,4,5-trimethoxybenzaldehyde and 3,4,5-trimethoxybenzoic acid. Minor phenolics with statistical significance (p < 0.0001) are phenylacetonitrile, vanillin, 4-hydroxyphenylethanol, 4-hydroxyphenylacetonitrile, and 2-hydroxyacetophenone. Phenylacetaldehyde, a common honey constituent is present at higher concentrations in thyme honey (p < 0.0001). Important non-phenolic components are 2-methylpropionic acid which was found at higher proportions in thyme honey (p = 0.002) and 4-(4-hydroxy-2,2,6-trimethyl-7-oxabicyclo[4.1.0]hept-1-yl)-3-buten-2-one, a norisoprenoid found solely in this type of honey.     

Flavour index and aroma profiles of fresh and processed honeys

This paper discusses the importance of flavour profiling in detecting indicative parameters for quality control of fresh and heated honey. Flavour compounds of six unifloral honeys (Lavandula stoechas, Castanea sativa, Dorycnium pentaphyllum, Rosmarinus officinalis, Eucalyptus sp and Robinia pseudoacacia) were investigated. The aroma extracts were obtained by a two‐step procedure involving (i) preliminary steam distillation under reduced pressure to evaluate the methylpyrazines generated in heated honeys by spectrophotometry (flavour index) and (ii) Likens–Nickerson's simultaneous steam distillation and solvent extraction (SDE) method with added NaCl. A combined total of 64 compounds were detected by gas chromatography/mass spectrometry (GC/MS), 58 of which were identified. Some compounds appeared to be characteristic of the floral source, particularly in Spanish lavender (methylated aliphatic acids and aromatic esters), eucalyptus (2,3‐pentanedione, acetoin, 1‐hexyl alcohol, 2‐acetyl‐5‐methylfuran, furfuryl propionate, 2‐phenylacetaldehyde and nerolidol), chestnut (acetophenone and 2‐aminoacetophenone), rosemary and D pentaphyllum (aromatic acids and esters, 2‐phenylacetaldehyde, farnesol and thymol) honeys. Robinia honey samples were characterised by very low levels of aromatic compounds. Twenty‐six flavour compounds were statistically closely related to the floral origin of the honeys (P ≤ 0.05). The flavour index was evaluated progressively in heated honeys, whereas in fresh honeys it showed a minimal value. © 2003 Society of Chemical Industry     

Assessment of phenolic profile of Turkish honeys

In this study, phenolic profile and antioxidant activity of 60 Turkish honey samples of nineteen different floral origins were evaluated by ultra-performance liquid chromatography with electrospray ionization coupled to tandem mass spectrometry, providing the identification of 32 phenolic compounds. Thyme (1051.58 mg/kg), pine (994.18 mg/kg), carob (935.03 mg/kg), eucalyptus (814.46 mg/kg), rhododendron (680.71 mg/kg), heather (562.59 mg/kg), cedar (561.83 mg/kg), and euphorbia (501.64 mg/kg) present significantly high phenolic content. Moreover ferulic, homogentisic, gentisic, syringic, 3,4-dihydroxybenzoic, caffeic, vanillic, p-coumaric, 4-hydroxy benzoic, and trans-2-hydroxy cinnamic acids were the most abundant of the determined compounds. The antioxidant activities of the honeys were evaluated by β-carotene-linoleic acid inhibition, DPPH free radical scavenging activity and ABTS⁺ cation radical scavenging activity which were measured as IC₅₀: 10.87 – 48.23 µg/mL, SC₅₀: 54.33 – 99.40 µg/mL and SC₅₀: 10.33 – 41.20 µg/mL, respectively. Phenolic compounds are considered antioxidant constituents, and they could be stated as components that account for antioxidant activity in Turkish honeys.     

Characterization of volatile compounds in Fen‐Daqu – a traditional Chinese liquor fermentation starter

Fen‐Daqu is a saccharifying agent and fermentation starter for the production of Chinese liquor Fen (alcoholic spirit) and Fen traditional vinegar. The volatile compounds produced at seven incubation steps were analysed by HS‐SPME‐GC‐MS. A total of 83 major volatile compounds were identified, including 23 esters, 8 acids, 24 alcohols, 18 ketones and aldehydes, 6 pyrazines and 4 acetals. Data obtained by HS‐SPME‐GC‐MS were subjected to principal component analysis. The trajectory plots of volatile compounds in Fen‐Daqu samples obtained during successive steps of incubation were revealed. The major compounds that contributed to discrimination were hexanal, (E)‐2‐octenal, (Z)‐2‐octen‐1‐ol, nonanoic acid, 1‐octanol, 2‐decen‐1‐ol, hexyl acetate, (E)‐2‐octen‐1‐ol, acetic acid, ethyl acetate, phenylethyl alcohol, ethyl alcohol, octanoic acid, 1‐octanol, 3‐methyl‐2‐buten‐1‐ol and pyrazines. Copyright © 2012 The Institute of Brewing & Distilling     

Phenolic composition and antioxidant activity of white mulberry (Morus alba L.) fruits

Eight major mulberry cultivars [Nakhonratchasima 60 (NS 60), Buriram 60 (BR 60), Chumphon (CP), Wavee (WV), Chaingmai (CM), Pikultong (PT), Kamphaengsaen (KS) and Kamnanchul (KJ)] cultivated in Thailand were assessed for their flavonoid and phenolic acid composition using HPLC and tested for antioxidant potential using 2,2‐diphenyl‐1‐picrylhydrazyl hydrate (DPPH) assay. The total phenolic content (TPC) ranged from 104.78 to 213.53 mg GAE/100 g DW, and total flavonoid content (TFC) ranged from 69.58 to 211.01 mg CE/100 g DW. The major flavonoid compounds in mulberry fruit cultivars were (+)‐catechin (309.26–750.01 mg/100 g DW), procyanidin B1 (62.59–224.41 mg/100 g DW), quercetin (5.36–58.42 mg/100 g DW), rutin (18.73–26.90 mg/100 g DW) and (?)‐epicatechin (8.47–29.21 mg/100 g DW). Gallic acid, cinnamic acid and p‐hydroxybenzoic acid were found to be the major phenolic acids in mulberry fruit cultivars. The gallic acid and cinnamic acid contents ranged from 7.33 to 23.90 mg/100 g DW and from 11.64 to 15.05 mg/100 g DW, respectively. p‐Hydroxybenzoic acid content ranged from 1.77 mg/100 g DW (PT) to 7.13 mg/100 g DW (KJ). DPPH‐scavenging ability was excellent for ethanolic extract of NS 60, and EC₅₀ value of NS 60 (241.83 μg mL^?1) was significantly lower than those of the others (P < 0.05). TPC and TFC of the mulberry fruit were positively correlated with the DPPH‐scavenging ability.     

Effect of Phenolic Compounds on the Pasting and Textural Properties of Wheat Starch

Pasting and textural properties of wheat starch were systematically investigated in the presence of 25 phytochemicals including phenolic acids, flavonoids, coumarins, stillbenes and tannins with a wide structural diversity. Overall, most of these phenolic compounds significantly changed functional properties of starch. Trans‐cinnamic acid increased the peak viscosity most by 37 RVU whereas catechin decreased it most by 14 RVU. All the phenolic compounds considerably increased the breakdown with the greatest effect by chlorogenic acid (135 RVU) and the least by chrysin (6 RVU). Esculetin caused the maximum increase in setback (38 RVU), and 3‐hydroxybenzoic acid caused the maximum decrease (103 RVU). All the phenolic compounds significantly reduced the peak time with the greatest effect by trans‐cinnamic acid. Chrysin and 3‐hydroxybenzoic acid most increased and decreased the hardness of starch gels stored at 23°C for 48 h by 3.9 and 24.2 g. Most of the phenolic compounds increased the adhesiveness with the greatest effect by 3‐hydroxybenzoic acid (72 g·s). pH changes of the starch suspension caused by the addition of phenolic compounds and their structural diversity affected these functional properties of wheat starch to different extents. This study may provide a basis for the use of phytochemicals in functional and starch‐based staple foods.     

Investigation of organic extractives from unifloral chestnut (Castanea sativa L.) and eucalyptus (Eucalyptus globulus Labill.) honeys and flowers to identification of botanical marker compounds

Ultrasound-assisted extraction was employed to investigate the composition of extractable compounds from unifloral chestnut and eucalyptus honeys. 1-phenylethanol and 2′-aminoacetophenone are the most powerful botanical markers of chestnut honey. Additionally, cis-cinnamyl alcohol, and p-hydroxyacetophenone were found exclusively in chestnut honey. Organic extractives from whole chestnut flowers were predominated by 1-phenylethanol, nonanal, benzyl alcohol, and nonanoic acid. Of the 16 compounds found in the flower extract, 13 were present in honey as well. Some of them are transferred directly to honey, while in other cases modification reactions take place. Eucalyptus honey is characterized by 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-3-hexanone, as well as exo-2-hydroxycineole and an unknown norisoprenoid. Aside from, acetoin, nonanal, methyl nonanoate, and dehydrovomifoliol were present in higher concentrations. In eucalyptus flower extracts, norisoprenoids were the most abundant compounds, all of which were also present in the honey samples. 3-Oxo-α-ionone comprised half of the total amount, followed by eucalyptol.     

Effect of thermal sterilization on ferulic, coumaric and cinnamic acids: dimerization and antioxidant activity

BACKGROUND: Some phenolic compounds, such as ferulic acid and p‐coumaric acid, exist in the form of free acids, in fruits, rice, corn and other grains. Thermal treatment (121 °C at 15–17 psi) for different times on ferulic, p‐coumaric and cinnamic acids as well as equimolar mixtures of these acids was investigated. RESULTS: Ferulic and p‐coumaric acids underwent decarboxylation, yielding dimeric products formed through their corresponding radical intermediates, while cinnamic acid was recovered unreacted. High‐performance liquid chromatography analysis showed no cross‐dimerization when equimolar mixtures of pairs of hydroxycinnamic acids were treated under the same conditions. Dimers were characterized as (E)‐4′,4″‐(but‐1‐ene‐1,3‐diyl)bis(2′‐methoxyphenol)) (dimer of 4‐vinylguaiacol) and (E)‐4,4′‐(but‐1‐ene‐1,3‐diyl)diphenol) (dimer of 4‐vinylphenol) by nuclear magnetic resonance and mass spectrometry. CONCLUSION: Sterilization by thermal processing produced dimers of ferulic and coumaric acid. The antioxidant activity of these dimers was greater than that of the respective hydroxycinnamic acids. These results may be relevant for fruits and grains that contain hydroxycinnamic acids and undergo sterilization processes such as canning. Copyright © 2012 Society of Chemical Industry     

Using flavonoids, phenolic compounds and headspace volatile profile for botanical authentication of lemon and orange honeys

This study evaluates the usefulness of flavonoids (naringenin, hesperetin, chrysin, galangin, kaempferol, luteolin, pinocembrin, and quercetin) and phenolic acids (caffeic acid and p-coumaric acid) together with 37 volatile compounds in the differentiation between lemon blossom honey (Citrus limon) and orange blossom honey (Citrus spp.). The total content of flavonoids and phenolic acids is twice as high in lemon honey (6.20 mg/100 g) as in orange honey (3.64 mg/100 g); naringenin and caffeic acid were the main compounds in all cases. Hesperetin, a floral marker of citrus honey, was not significantly different for the two types of honey. A multivariate PLS2 analysis showed that some volatile compounds such as, 4 lilac aldehydes and bencenacetaldehyde (all abundant in orange honey) were negatively correlated with 4 flavonoids: pinocembrin, chrysin, naringenin and quercetin, and caffeic phenolic acid (all abundant in lemon honey). Moreover, the last 5 compounds were positively correlated with: 6 alcohols, 2 ketones, acetaldehyde and furanmethanol. This is a first approach to employ all of these compounds together with appropriate statistical techniques to differentiate between two varieties of citrus honey, and therefore it could be an interesting tool for their authentication.     

Vodka production from potato (Solanum tuberosum L.) using three Saccharomyces cerevisiae isolates

The efficacy of three strains of Saccharomyces cerevisiae in the production of vodka from potato hydrolysate was evaluated. For each isolate, two treatments were performed: one containing potato hydrolysate (11% w/w of soluble solids) and the other containing potato hydrolysate supplemented with sucrose (17% w/w) in the fermentation medium. The best results were obtained using a baker's yeast in the second treatment, which showed higher substrate‐to‐product conversion (0.47 g ethanol g^?1 total reducing sugars), higher fermentation yield (91.4%) and a higher ethanol content (6.05% v/v). Following fermentation, the medium was clarified using centrifugation, and two successive distillations and filtrations were conducted. The results were examined by referring to the standards for vodka, as established by Brazilian legislation. The ethanol concentration (39.7% v/v) fell within the legally stipulated range, and the levels of copper and furfural remained undetectable. However, the methanol (35.04 mg 100 mL^?1 of anhydrous alcohol) content and the levels of some secondary compounds (148.33 mg 100 mL^?1) were both higher than the guidelines (20 and ≤50 mg 100 mL^?1, respectively). Copyright © 2016 The Institute of Brewing & Distilling     

Cinnamic acid derivatives in cosmetics: current use and future prospects

Cinnamic acid derivatives are widely used in cosmetics and possess various functions. This group of compounds includes both naturally occurring and synthetic substances. On the basis of the Cosmetic Ingredient Database (CosIng) and available literature, this review summarizes their functions in cosmetics, including their physicochemical and biological properties as well as reported adverse effects. A perfuming function is typical of many derivatives of cinnamaldehyde, cinnamyl alcohol, dihydrocinnamyl alcohol and cinnamic acid itself; these substances are commonly used in cosmetics all over the world. Some of them show allergic and photoallergic potential, resulting in restrictions in maximum concentrations and/or a requirement to indicate the presence of some substances in the list of ingredients when their concentrations exceed certain fixed values in a cosmetic product. Another important function of cinnamic acid derivatives in cosmetics is UV protection. Ester derivatives such as ethylhexyl methoxycinnamate (octinoxate), isoamyl p‐methoxycinnamte (amiloxiate), octocrylene and cinoxate are used in cosmetics all over the world as UV filters. However, their maximum concentrations in cosmetic products are restricted due to their adverse effects, which include contact and a photocontact allergies, phototoxic contact dermatitis, contact dermatitis, estrogenic modulation and generation of reactive oxygen species. Other rarely utilized functions of cinnamic acid derivatives are as an antioxidant, in skin conditioning, hair conditioning, as a tonic and in antimicrobial activities. Moreover, some currently investigated natural and synthetic derivatives of cinnamic acid have shown skin lightening and anti‐ageing properties. Some of them may become new cosmetic ingredients in the future. In particular, 4‐hydroxycinnamic acid, which is currently indexed as a skin‐conditioning cosmetics ingredient, has been widely tested in vitro and in vivo as a new drug candidate for the treatment of hyperpigmentation.     

4 种新疆单花蜜挥发性成分的SPME-GC-MS 分析

采用固相微萃取(SPME)气质联用(GC-MS)分析新疆地区沙枣蜜、油菜蜜、葵花蜜以及棉花蜂蜜4 种单花蜜的挥发性成分。结果表明：39 份样品共检测出144 种挥发性成分;芳樟醇、2-(1,1- 二甲基)- 环己醇和联苯为沙枣蜜的特征性挥发组分;雪松醇为油菜蜜的特征性挥发物质;4- 萜品醇、9-(3,3- 二甲基- 环氧乙烷-2- 烷基)-2,7- 二甲基- 九碳-2,6- 二烯醇、2- 莰烯、1- 甲基-4- 异丙烯基苯、桃金娘烯醇、α,α,4- 三甲基-2,4- 环己二烯-1- 甲醇、α- 萜品醇为葵花蜜的特征性挥发物质,其中4- 萜品醇是葵花蜜最显著的特征性挥发物质;3- 苯基丙烯醛、3- 苯基-2- 丙烯醇为棉花蜜的特征性挥发组分。     

Fatty acid composition and biological activities of volatiles from fruits of two Tunisian olive cultivars

This study investigates volatile compounds, fatty acid composition and antioxidant, antibacterial and antifungal activities of fruits from two olive cultivars (Chemlali and Neb Jmel). Fatty acid profiles varied significantly between cultivars (cvs) where Neb Jmel seem to have higher contents of palmitic and oleic acids (16.4% and 66.4%, respectively) and lower of linoleic acid (9.4%). The volatile profile indicated the apparent difference between cvs. In fact, the main components detected in Chemlali cv. were (E,E)‐2,4‐decadienal (23.0%), (E,Z)‐2,4‐decadienal (14.9%) and nonanal (6.7%), while 3‐ethenylpyridine (15.5%), (E)‐2‐decenal (14.4%) and (E)‐2‐undecenal (7.0%) were the major components in Neb Jmel cv. Furthermore, these volatiles were subjected to screening for their possible antioxidant activities where volatiles from Neb Jmel fruits were found to be better. Results presented here may suggest that the volatiles fraction of two cultivars possess antimicrobial and antifungal activities.     

Exploring stingless bee honey from selected regions of Peninsular Malaysia through gas chromatography–mass spectrometry–based untargeted metabolomics

Volatile organic compounds in honey are known for their considerable impact on the organoleptic properties of honey, such as aroma, flavor, taste, and texture. The type and composition of volatile organic compounds are influenced by entomological, geographical, and botanical origins; thus, these compounds have the potential to be chemical markers. Sixty-two volatile compounds were identified using gas chromatography–mass spectrometry from 30 Heterotrigona itama (H. itama) honey samples from 3 different geographical origins. Hydrocarbons and benzene derivatives were the dominant classes of volatile organic compounds in the samples. Both clustering and discriminant analyses demonstrated a clear separation between samples from distant origins (Kedah and Perak), and the volcano plot supported it. The reliability and predictability of the partial least squares–discriminant analysis model from the discriminant analysis were validated using cross-validation (R²: 0.93; Q²: 0.83; accuracy: 0.97) and the permutation test (p < 0.001), and the output depicted that the model is legitimate. In combination with the variable importance of projection (VIP > 1.0) and the Kruskal–Wallis test (p < 0.01), 19 volatile organic compounds (encompassed aldehydes, benzene derivatives, esters, hydrocarbons, and terpenoids) were sorted and named potent chemical markers in classifying honey samples from three geographical origins. In brief, this study illustrated that volatile organic compounds of stingless honey originated from the same bee species, but different geographical origins could be applied as chemical markers.     

Selection of Volatile Aroma Compounds by Statistical and Enological Criteria for Analytical Differentiation of Musts and Wines of Two Grape Varieties

ABSTRACT: Aroma compounds in Airen and Macabeo musts and wines were submitted to multivariate analysis of variance and only those significantly depending (p < 0.05) on grape variety, prefermentative treatment, and exhibiting no significant interaction were selected for discriminant analysis. Benzyl alcohol, Z‐3‐hexen‐1‐ol, hexanoic acid, benzaldehyde, β‐ionone, and E‐nerolidol contents in musts were used to calculate 2 discriminating functions, which allow classifying 100% of all must by variety and treatment. Discriminant analysis carried out with 1‐propanol, isoamyl alcohol, 2‐phenylethanol, ethyl acetate, ethyl propanoate, ethyl lactate, isobutyl acetate, and 7‐butyrolactone contents in wines, allows to establish 2 other functions, which led to accurate classification of 100% of the wine samples.     

Impact of fining agents on the volatile composition of sparkling mead

Sparkling mead is obtained by secondary fermentation of the mead involving the addition of starter yeast culture, sucrose, nutrients and fining agents. The aim of this study was to evaluate the effect of different fining agents (tannins vs combined fining agents) on the volatile composition of sparkling mead. Sparkling mead was produced from a base mead using a commercial yeast strain (Saccharomyces bayanus) and the volatile compounds were determined by gas chromatography–flame ionisation detection and gas chromatography–mass spectrometry. Thirty six volatile compounds were quantified and the major groups were alcohols (73.2%), acetates (19.1%), carbonyl compounds (5.5%) and ethyl esters (1.2%), represented by 3‐methyl‐1‐butanol, ethyl acetate, acetaldehyde and monoethyl succinate, respectively. The remaining compounds were present at <1%. Eleven volatile compounds exhibited odour activity values >1, with ethyl octanoate and ethyl hexanoate contributing to the aroma of sparkling mead, with fruity, strawberry and sweet notes. The combined fining agents caused a marked decrease in the concentration of volatile compounds compared with tannins. In general, 3‐ethoxy‐1‐propanol, ethyl lactate, ethyl octanoate, diethyl succinate, diethyl malate, monoethyl succinate, 2‐methylpropanoic acid, hexanoic acid, octanoic acid, acetaldehyde, acetoin, furfural, benzaldehyde, 5‐hydroxymethylfurfural, trans‐furan linalool oxide, cis‐furan linalool oxide and 4‐oxo‐isophorone decreased in concentration. Conversely, 1‐propanol and 2‐methylpropanoic acid (tannins) and ethyl butyrate (combined fining agents) increased in concentration. The remaining volatile compounds were not affected. Significant differences (p < 0.05) were found for 19 volatile compounds independently of the type of fining agents used. © 2018 The Institute of Brewing & Distilling     

Antioxidant phenolic compounds of pomegranate wines produced by different maceration methods

Various methods were evaluated in the production of ‘Hicaz’ pomegranate wine by microvinification. The chemical, phenolic and antioxidant characteristics of the wines were assessed by measurement of water‐soluble dry matter, acidity, density, alcohol content, volatile acidity, total monomeric anthocyanins, polarized colour intensity and individual phenolic compounds. Three different methods – classical maceration (N), seed‐supplemented maceration (S) and seed + enzyme supplemented maceration (E) – were applied. Total phenolic compounds of pomegranate must and wines (after 18 months of storage) were 1897 mg/L (must), 1663 mg/L (N), 1339 mg/L (E) and 1414 mg/L (S). Phenolic compounds in pomegranate must and wines included gallic acid, vanillic acid, caffeic acid, ferulic acid, p‐coumaric acid, hydroxycinnamic acid, epicatechin and catechin. Total antioxidant capacities (Trolox equivalents) of pomegranate must and wines (N, E and S) were 9.9 mm /L (must), 9.8 mm /L (N), 9.7 mm /L (E) and 9.5 mm /L (S). Copyright © 2017 The Institute of Brewing & Distilling     

Effect of γ-irradiaton on the volatile compounds of licorice (Glycyrrhiza uralensis Fischer)

The volatile compounds of non-irradiated and 1, 3, 5, 10 and 20 kGy γ-irradiated roots of licorice (Glycyrrhiza uralensis Fischer) were isolated by simultaneous distillation–extraction (SDE) technique and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 61 volatile compounds belonging to the chemical classes of acid (2), alcohol (16), aldehyde (8), ester (6), furan (2), hydrocarbon (14), ketone (10) and N-containing compounds (3) were identified in non-irradiated licorice. The prime volatile compound of licorice was 2-ethoxy-1-propanol, which makes up to 22.82% of the total composition. Over a dose of 1 kGy, another compound, benzaldehyde appeared, whereas other compounds, 3,5-dimethyl octane and phenethyl alcohol, disappeared at the dose of 20 kGy. Though the content of several volatile compounds increased after γ-irradiation, the content of major volatile compounds such as 4-terpineol, myrtenal, tetramethylpyrazine, hexanoic acid, azulene and p-cymene decreased. In comparison to non-irradiated licorice, 10 kGy dose of irradiation induced the maximum level of total yield of volatile compounds by 12%, but slightly decreased at 20 kGy. Therefore, the application of γ-irradiation is feasible without major qualitative and quantitative loss of volatile compounds when exposed at 10 kGy.     

Comparative analysis of the chemical composition and antioxidant activity of red (Psidium cattleianum) and yellow (Psidium cattleianum var. lucidum) strawberry guava fruit

Abstract: Strawberry guava (Psidium cattleianum Sabine) is a native fruit of Brazil widely consumed fresh and used in the food industry. In this context, the present study deals with the chemical characterization and the antioxidant activity of the red (Psidium cattleianum) and yellow (P. cattleianum var. lucidum Hort.) strawberry guava fruits, cultivars Irapuã and Ya‐Cy, respectively. Knowledge of chemical composition is fundamental to human nutrition, contributing to the quality of foods. Phenolic compounds in both fruits were analyzed by HPLC–DAD and the total flavonoid content was determined by the Folin–Ciocalteu assay. The antioxidant activity was evaluated by the total reactive antioxidant (TRAP) method. Psidium cattleianum presented a higher content of polyphenolic compounds than P. cattleianum var. lucidum (501.33 and 292.03 mg/100 g, respectively), with hyperoside being one of the major flavonoids identified for both cultivars. In addition to flavonoids, P. cattleianum presented an anthocyanin, identified as cyanidin. The antioxidant activity varied in a concentration‐dependent manner for both strawberry guava species. The volatile oils in fruits and fatty acids in seeds were quantified by GC‐EM. The analysis of the essential oil of yellow strawberry guava was compared with a previous study on the red cultivar, revealing β‐caryophyllene as the main component in both oils. The fatty acid composition was also quite similar and was especially characterized by the presence of unsaturated fatty acids (86.25% and 76%, respectively), among which linoleic acid as the most abundant. Practical Application: In this study, the chemical characterization and the antioxidant activity of the red (Psidium cattleianum) and yellow (P. cattleianum var. lucidum Hort.) strawberry guava fruits were investigated. This is important for potential application of strawberry guava as functional food. Moreover, it may be the experimental basis for further development and use in food industry.