Flavour and off-flavour compounds of black and white pepper (Piper nigrum L.) II. Odour activity values of desirable and undesirable odorants of black pepper

Quantification of 14 odorants and calculation of their odour activity values were the basis of an aroma model reflecting most of the odour notes of black pepper. Omission tests indicated α- and β-pinene, myrcene, α-phellandrene, limonene, linalool, methylpropanal, 2- and 3-methylbutanal, butyric acid and 3-methylbutyric acid as key odorants. A storage experiment revealed that for ground black pepper, losses of α-pinene, limonene and 3-methylbutanal were mainly responsible for deficits in the pepper-like, citrus-like, terpene-like and malty notes after 30?days at room temperature. The musty/mouldy off-flavour of a sample of black pepper was caused by a mixture consisting of 2,3-diethyl-5-methylpyrazine (2.9?μg/kg) and 2-isopropyl-3-methoxypyrazine (0.2?μg/kg).     

Flavour and off-flavour compounds of black and white pepper (Piper nigrum L.) I. Evaluation of potent odorants of black pepper by dilution and concentration techniques

 Dilution and concentration experiments as well as enantioselective analysis of optically active monoterpenes indicated (±)-linalool, (+)-α-phellandrene, (–)-limonene, myrcene, (–)-α-pinene, 3-methylbutanal and methylpropanal as the most potent odorants of black pepper. Additionally, 2-isopropyl-3-methoxypyrazine and 2,3-diethyl-5-methylpyrazine were detected as important odorants of a black pepper sample with a mouldy, musty off-flavour. Received: 24 September 1998     

Important odorants of sweet bell pepper powder (Capsicum annuum cv. annuum): differences between samples of Hungarian and Morrocan origin

 By application of gas chromatography–olfactometry on aroma extracts prepared from Hungarian sweet bell pepper powder (HBP) and Moroccan sweet bell pepper powder (MBP), 35 and 42 odour-active compounds were detected in the HBP and the MBP, respectively. The identification experiments, in combination with the flavour dilution (FD) factors obtained by application of aroma extract dilution analysis, revealed that β-ionone (violet-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol; caramel-like), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (Sotolon; seasoning-like) and 2- and 3-methylbutanoic acids had the highest odour activities (FD factors of 8192 to 32768) among the 33 odorants that could be identified in the HBP. All odorants identified in the HBP were also characterized as odour-active volatiles in the MBP. The overall different aroma of the Moroccan sample could, however, be attributed to the lower FD factors of the five key odorants mentioned above and, in addition, to the higher FD factors of 10 odorants not present among the aroma compounds of the HBP, e.g. (Z)-1,5-octadien-3-one. In total, 20 odour-active volatiles are reported here for the first time as volatile bell pepper constituents. Received: 30 July 1999 / Revised version: 11 October 1999     

The effect of supplementation of a white clover or perennial ryegrass diet with grape seed extract on indole and skatole metabolism and the sensory characteristics of lamb

Condensed tannin in the form of a grape seed extract (GSE) was dosed to weaned wether lambs fed white clover (WC) or perennial ryegrass (PRG) over a 9‐week period to determine whether the ‘pastoral’ flavour and odour of meat could be altered. The concentrations of the pastoral flavour compounds indole and skatole were determined in the rumen fluid, blood plasma and intermuscular fat. The odour and flavour of fat and meat from the slaughtered lambs was assessed by a trained panel. The rumen fluid and blood plasma concentrations of indole and skatole were higher in those lambs fed WC compared to PRG (P < 0.05) and the overall meat flavour intensity was greater when feeding WC (P < 0.01). The observed concentration of indole and skatole in the fat between WC and PRG feeding treatments was not statistically different. Power analysis indicated that increasing the number of lambs per treatment group from 20 to 65 would result in a higher fat skatole concentration (P < 0.05) being detected in lambs fed WC compared to PRG. Dosing with GSE gave a small reduction in skatole concentration in the rumen fluid and reduced plasma concentration of indole and skatole (P < 0.001). Odour and flavour scores of the fat and meat samples were not particularly high however, dosing with GSE lowered the overall and sweet odour and the sheepy, camphor, faecal and barnyard flavour (P < 0.05). Although the plasma concentration of indole and skatole suggests that GSE reduced indole and skatole formation, the intermittent supply of the GSE to the rumen environment was not sufficient to reduce their concentration in the fat. Hence, the small difference in the scores for pastoral odour and flavour attributes associated with GSE treatment may arise from other unknown factors. From a primary investigation, there was no difference in the concentration of indole and skatole in fat samples collected from carcasses before and after chilling. Further investigations into meat pastoral flavour are warranted through feeding condensed tannin‐containing forages. Copyright © 2007 Society of Chemical Industry     

Potent odorants resulting from the peroxidation of lemon oil

Summary The odorants of a lemon oil sample, which was peroxidized for 120 h at room temperature in the presence of light, were analysed by an aroma extract dilution procedure. On the basis of their FD factors carvone,p-methylacetophenone,p-cresol, 4-acetyl-1-methyl-1-cyclohexene and 4 hydroperoxides were identified as the most intense odorants. Changes in the concentrations of neral, geranial, linalool (odorants of the fresh lemon oil), carvone,p-methylacetophenone,p-cresol andp-cymene (dependent on the storage time) were determined and the odour units for these compounds were calculated.

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Intensive Geruchsstoffe aus peroxidiertem Zitronenol

Zusammenfassung Die intensivsten Geruchsstoffe eines Zitronenöls, das 120 h bei Raumtemperatur bestrahlt worden war, wurden identifiziert. Eine Aromastoffverdünnungsanalyse ergab hohe FD-Faktoren bei Carvon,p-Methylacetophenon,p-Kresol, 4-Acetyl-1-methyl-l-cyclohexen und bei vier Limonenhydroperoxiden. Vom Neral, Geranial und Linalool (Geruchsstoffe des frischen Öls) Bowie vom Carvon,p-Methylacetophenon,p-Kresol undp-Cymen wurde die Konzentration in Abhangigkeit von der Lagerzeit bestimmt und der Aromawert berechnet.

     

Fishy and hay-like off-flavours of dry spinach

 Gas chromatography-olfactometry of headspace samples revealed that (Z)-3-hexenal, methanethiol, (Z)-1,5-octadien-3-one, dimethyl trisulphide, octanal, 2-isopropyl- and 2-sec-butyl-3-methoxypyrazine are potent odorants of raw spinach. Boiling the spinach led to a change, such that dimethyl sulphide, methanethiol, dimethyl trisulphide, methional and 2-acetyl-1-pyrroline became the most important odorants. A further change was observed after drying and storage of raw spinach: methylpropanal, 2- and 3-methylbutanal and propanal were identified as the odorants with higher odour activity values. It was also found that (Z)-1,5-octadien-3-one and methional, in a concentration ratio of about 1 : 100, are responsible for the fishy off-flavour as dry spinach stored at lower temperatures under nitrogen. The hay-like flavour was caused by oxidative degradation of furan fatty acids, yielding 3-methyl-2,4-nonanedione. Received: 24 July 1997     

Fishy and hay-like off-flavours of dry spinach

 Gas chromatography-olfactometry of headspace samples revealed that (Z)-3-hexenal, methanethiol, (Z)-1,5-octadien-3-one, dimethyl trisulphide, octanal, 2-isopropyl- and 2-sec-butyl-3-methoxypyrazine are potent odorants of raw spinach. Boiling the spinach led to a change, such that dimethyl sulphide, methanethiol, dimethyl trisulphide, methional and 2-acetyl-1-pyrroline became the most important odorants. A further change was observed after drying and storage of raw spinach: methylpropanal, 2- and 3-methylbutanal and propanal were identified as the odorants with higher odour activity values. It was also found that (Z)-1,5-octadien-3-one and methional, in a concentration ratio of about 1 : 100, are responsible for the fishy off-flavour as dry spinach stored at lower temperatures under nitrogen. The hay-like flavour was caused by oxidative degradation of furan fatty acids, yielding 3-methyl-2,4-nonanedione. Received: 24 July 1997     

Simple phenols and indoles in anaerobically stored piggery wastes

Phenol, p-cresol, 4-ethylphenol, indole and skatole, which contribute to a large extent to the bad smell of piggeries, were estimated in anaerobically stored piggery wastes. p-Cresol, indole and skatole were also found in freshly voided faeces. Phenol, p-cresol and 4-ethylphenol are present in the urine as their glucuronides. It was shown that upon contact of urine and faeces, the urinary glucuronides are hydrolysed almost instantly liberating phenols. This hydrolysis is caused by the high β-glucuronidase activity of faeces. Protein degradation followed by transformation of tyrosine and tryptophane were found to be additional processes contributing to the accumulation of phenol, p-cresol, indole and skatole during the anaerobic storage of piggery wastes.     

Hay-like off-flavour of dry parsley

 The flavour of parsley was found to change during drying and storage. Quantification of 27 potent odorants, selected by dilution experiments and calculation of odour activity values, indicated that 3-methyl-2,4-nonanedione was mainly responsible for the hay-like off-flavour. Two furanoid fatty acids, known to be precursors of 3-methyl-2,4-nonanedione, were detected in dry parsley. The decrease in the intensities of the parsley-like, metallic and green notes in the odour profile during storage of dry parsley was due to losses of p-mentha-1,3,8-triene, myrcene and (Z)-6-decenal. Sulphurous cabbage-like and malty notes were caused by dimethyl sulphide, methylpropanal as well as 2- and 3-methylbutanal. The effect of the water activity (at a _w levels of 0.15, 0.25, 0.35) on the changes in the concentrations of all these compounds during storage of dry parsley was investigated. Received: 24 July 1997     

Influence of different storage conditions on changes in the key aroma compounds of orange juice reconstituted from concentrate

Quantification of aroma compounds in an orange juice reconstituted from concentrate which had been stored at 37 °C for 4 weeks (forced storage) revealed an increase in the concentrations of, in particular, dimethyl sulphide, 2-methoxy-4-vinylphenol, α-terpineol, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF) in comparison with the same orange juice before storage. On the other hand, clearly lower concentrations were found for octanal, decanal, (R)-α-pinene, linalool, and (E)-β-damascenone after storage, while the concentrations of vanillin and carvone remained nearly constant. Similar results were found for the same aroma compounds after storage of the orange juice at 20 °C for 1 year. Sensory experiments corroborated the importance of 2-methoxy-4-vinylphenol and dimethyl sulphide for the typical stale off-flavour of the stored orange juice, while the omission of e.g., α-terpineol in model mixtures could not be detected. Under both storage conditions (37 °C for 4 weeks or 20 °C for 1 year), the breakthrough odour thresholds of α-terpineol and 4-HDF were not reached, while the concentrations of dimethyl sulphide and 2-methoxy-4-vinylphenol clearly exceeded their breakthrough odour thresholds, thus confirming the crucial role of these odorants for the off-flavour of stored orange juice from concentrate. In addition, changes in the concentrations of selected orange juice odorants at various temperatures and times were investigated.     

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing

The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B₁, B₂, G₁ and G₂ and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p?<?0.05). The lowest and highest reduction of aflatoxin B₁, which is the most dangerous aflatoxin, was 20.5%?±?2.7% using benzoic acid and 54.5%?±?2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p?<?0.05).     

Effect of Acetic Acid and Commercial Protease Pretreatment on Salting and Characteristics of Salted Duck Egg

Salting of duck egg pretreated with 5% acetic acid and different commercial proteases (flavourzyme, protamex, alcalase, and neutrase) was studied. After 2 weeks of salting, duck eggs soaked in 5% acetic acid for 30 min, followed by soaking in 5% (w/v) flavourzyme and neutrase had the highest hardening ratio (90.14 ± 2.43%, 90.25 ± 1.23%) with the coincidental increase in salt content in egg white and decrease in moisture content of yolk, compared with those from other treatments (p < 0.05). However, similar hardening ratio of the sample treated with alcalase was obtained to that of sample treated with either flavourzyme or neutrase (P > 0.05). After 1 week of salting, protamex showed the similar effect on hardening ratio to other proteases (p > 0.05). When eggs were pretreated with neutrase at different concentrations (0.25%, 0.5%, and 0.75%, w/v) for different times (30, 60, and 90 min), those pretreated with 0.25% (w/v) neutrase for 90 min had the shorter salting time, while soaking time did not have the impact on hardening ratio for egg treated with 0.5% and 0.75% neutrase (P > 0.05). The oil exudation of egg treated with 0.25% neutrase had the higher oil exudates than the control at week 2 and 3 of salting (P < 0.05). Treatment of neutrase had no impact on viscosity of egg white, regardless of salting time (P > 0.05). Microstructure study revealed that shell of salted egg pretreated with acetic acid had rough and porous surfaces when compared with control, whereas no changes in microstructure and FTIR spectra of shell membrane were found. Therefore, pretreatment of egg with 5% acetic acid for 30 min, followed by 0.25% neutrase for 90 min prior to salting could expedite the salting process and yielded egg yolk with hardening ratio and oil exudates, comparable to the traditionally salted egg.     

Effect of a Polyphenol–Vacuum Packaging on Lipid Deterioration During an 18-Month Frozen Storage of Coho Salmon (<Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis>)

A packaging system combining a polyphenol-rich film and vacuum (PPRF–VP) was applied to farmed coho salmon (Oncorhynchus kisutch) muscle for an 18-month storage (−18 °C). For it, two different concentrations of polyphenol compounds (namely, p-coumaric and ferulic acids) obtained from a barley husk extract were applied (PPRF–VP conditions) and compared to vacuum packaging without polyphenol presence (vacuum control; VP condition) and to packaging in the absence of vacuum and polyphenols (control; CP condition). The study was addressed to lipid hydrolysis and oxidation development and to lipid changes related to nutritional value. Both PPRF–VP conditions provided an inhibitory effect (p < 0.05) on conjugated diene and fluorescent compound formation in frozen salmon. Compared to CP condition, vacuum packaging (PPRF–VP and VP conditions) led to lower (p < 0.05) peroxide and anisidine values and to an inhibitory effect (p < 0.05) on α- and γ-tocopherol losses. No effect (p > 0.05) of polyphenol presence and vacuum packaging could be inferred on free fatty acid formation (hydrolysis development) and on polyunsaturated fatty acid retention (polyene index assessment). A low rancid odour development was observed in all kinds of fish samples, this being lower (p < 0.05) in fish kept under vacuum (PPRF–VP and VP) conditions.     

Aroma-active compounds of butter: a review

This review article shows that more than 230 volatile compounds have been identified in butter, however, only a small number of them can be considered as key odorants of butter aroma. Gas chromatography olfactometry was used to determine the character impact odorants of different kinds of butter. Sweet cream butter is characterised by lactones with fruity and creamy notes and by sulphur compounds, having corn-like and garlic odours. The key odour compounds of sour cream butter are diacetyl (buttery-like), butanoic acid (cheesy) and δ-decalactone (peach), mainly due to lactic acid bacteria fermentation. The aroma of butter oil is characterised by aldehydes, such as (E)- and (Z)-2-nonenal and (E,E)-2,4-decadienal, conferring green and oily notes. Olfactometric studies of heated butter showed the formation of new aroma compounds during heating, such as 3-methylbutanoic acid (cheesy), methional (potato-like) and 2,5-dimethyl-4-hydroxy-3-(2H)-furanone (caramel-like). High temperature treatment of butter can also induce off-flavour development. Off-odours in butter originate from autooxidative and as well as from lipolytic reactions, microbial contamination and animal feeding. The views expressed in this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use, which might be made of the information contained herein.     

Effect of Freezing and Frozen Storage on Phenolic Compounds of Raspberry and Blackberry Cultivars

The phenolic compounds in raspberry and blackberry cultivars grown in Turkey were determined by liquid chromatography–mass spectrometry (MS)/MS in fresh, just-frozen, and stored fruits at −22 °C for 6 months period. The major phenolic compounds in water extracted samples were ellagic acid (1,350.36–727.9 mg/kg fresh fruit), ferulic acid (820.78–338.27 mg/kg fresh fruit), caffeic acid (754.85–202.78 mg/kg fresh fruit), p-coumaric acid (361.68–142.63 mg/kg fresh fruit), p-hydroxybenzoic acid (534.20–233.29 mg/kg fresh fruit), and quercetin (46.97–27.31 mg/kg fresh fruit) in raspberry and ellagic acid (1,828.07–1,555.13 mg/kg fresh fruit), ferulic acid (757.69–413.82 mg/kg fresh fruit), caffeic acid (736.85–337.89 mg/kg fresh fruit), p-coumaric acid (877.45–287.15 mg/kg fresh fruit), and quercetin (74.69–56.78 mg/kg fresh fruit) in blackberry. The varietal differences in the phenolic compound contents were larger among the blackberry cultivars (from 1,828.07 to 56.78 mg/kg fresh fruit) than among the raspberry cultivars (1,350.36 to 27.31 mg/kg fresh fruit). A significant decrease was observed in the content of p-hydroxybenzoic acid (from 534.20 to 114.30 mg/kg; Aksu Kırmızısı) and the least decrease was in the content of caffeic acid (from 545.42 to 530.91 mg/kg; Heritage) in raspberry cultivars. On the other hand, ferulic acid (from 475.16 to 113.33 mg/kg) decreased significantly in blackberry (Bursa 2) after storage for 6 months.     

A review on conventional and biotechnological approaches in white pepper production

White pepper is the dried seeds obtained from pepper berries (Piper nigrum L.) after the removal of the pericarp. It has been widely used as seasoning and condiments in food preparation. Globally, white pepper fetches a higher price compared to black pepper due to its lighter colour, preferable milder flavour and pungency. Increasing global demand of the spice outpaced the supply as the conventional production method used is laborious, lengthy and also not very hygienic. The most common conventional method is water retting but can also include pit soil, chemical, boiling, steaming and mechanical methods. The introduction of a biotechnological approach has gained a lot of interest, as it is a more rapid, convenient and hygienic method of producing white pepper. This technique involves the application of microorganisms and/or enzymes. This review highlights both conventional and latest biotechnological processes of white pepper production. © 2018 Society of Chemical Industry     

Phenolic Content and Antioxidant Activity of Moscatel Dessert Wines from the Setúbal Region in Portugal

Moscatel wines from Setúbal were analyzed for their total phenolic (mean value 1,243 mg gallic acid equivalents/L), and total flavonoid (mean value 248 mg catechin/L) composition by spectrophotometric and chromatographic methods were used to quantify phenolic compounds as benzoic acids, cinnamic acids, stilbens, and some flavonoids. Antioxidant activity of the wines was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH; mean value 70.7% inhibition), ferric reducing antioxidant power (FRAP; mean value 3,098 mg of Trolox equivalents/L) and oxygen radical absorbance capacity (ORAC; mean value 10,724 μmol/L) assays. Results were analyzed using principal component analysis which allowed samples to be grouped in terms of both winemaking producer and vintage. By plotting correlation loadings, it was possible to understand which variables were responsible for sample distribution. The correlation between results obtained for variables show that, in general, total flavonoid content is a better estimation of antioxidant activity in Moscatel samples (r _{ORAC/flavonoids} = 0.832, r _{FRAP/flavonoids} = 0.677) than total phenolic content (r _{ORAC/phenolics} = 0.680, r _{FRAP/phenolics} = 0.372). No major correlations were detected for DPPH assay results (r _{DPPH/flavonoids} = 0.283, r _{DPPH/phenolics} = 0.271). Chromatographic profiles showed important differences among Moscatel wines. Gallic acid contents and results of antioxidant activity tests were strongly correlated (r values in the range 0.74–0.92). Correlations of the results obtained for antioxidant activity tests with contents of other phenolic compounds such as ethyl caffeate, ethyl gallate, caffeic acid, protocatechuic acid, and t-caftaric acid depend on sample and type of test employed. Presented at the “AOAC Europe section international workshop: Enforcement of European Legislation on Food and Water: Analytical and Toxicological Aspects”, in Lisbon, April 2008, and published in abstract form.     

Water extractable phytochemicals from Capsicum pubescens (tree pepper) inhibit lipid peroxidation induced by different pro-oxidant agents in brain: in vitro

This study seeks to determine the antioxidant and neuroprotective properties of aqueous extract of ripe and unripe Capsicum pubescens (tree pepper) on some pro-oxidant induced lipid peroxidation in rat’s brain (in vitro). The total phenol, vitamin C, ferric reducing antioxidant property (FRAP) and Fe (II) chelating ability of the extracts of C. pubescens were determined. Thereafter, the ability of the extracts to inhibit lipid peroxidation (induced by FeSO₄, sodium nitroprusside or quinolinic acid) in rat’s brain homogenates (in vitro) was determined. The results of the study revealed that ripe C. pubescens had a significantly higher (P < 0.05) total phenol content [ripe (113.7 mg/100 g), unripe (70.5 mg/100 g)] and reducing power than the unripe pepper. However, there was no significant difference (P > 0.05) in the vitamin C [ripe (231.5 μg/g), unripe (224.4 μg/g)] content and Fe (II) chelating ability of the extracts. However, both extracts significantly (P < 0.05) inhibited lipid peroxidation induced by the pro-oxidant agents [25 μM Fe(II), 7 μM sodium nitroprusside and 1 mM quinolinic acid] in the rat’s brain homogenates in a dose-dependent manner. Nevertheless, the ripe pepper extracts inhibited MDA (Malondialdehyhide) production in the rat’s brain homogenates than the unripe pepper. Conversely, both extracts did not significantly (P > 0.05) inhibit Fe (II)/H₂O₂ induced decomposition of deoxyribose. It was therefore concluded that ripe and unripe C. pubescens would inhibit lipid peroxidation in rat brain in vitro. However, the ripe pepper was a more potent inhibitor of lipid peroxidation in the rat’s brain; this is probably due to its higher phenol content and reducing power.     

Effect of Ensilaging and Organic Solvent Treatment on Activity of Proteases from Chicken Intestine

Studies were carried out to assess the extractability of proteins from chicken intestine and to determine the activity of proteases in crude extract. Further, the activity of proteases was evaluated in acid and fermented chicken intestinal silage as well as in organic solvent-treated intestinal samples. Extractability of proteins was in the range of 3.85–4.06 mg/ml and was not affected (p ≥ 0.05) by the four different extractants, viz., distilled water, phosphate buffer, and 1% potassium chloride with or without 0.1 M Na₂EDTA. The specific activity of acidic and alkaline proteases were in the range of 4.78–7.26 and 19.31–24.07 units, respectively, and was not affected (p ≥ 0.05) by the type of extractant used. The pH profile for activity showed higher activity in the alkaline pH range. Addition of acid or ingredients for fermentation reduced the extractability of protein significantly (p ≤ 0.05). During storage of silage, the reduction in enzyme activity was higher in acid silage compared with fermented silage. Treatment of chicken intestine with organic solvents enhanced the enzyme activity and higher increase was observed with isopropyl alcohol-treated intestine. During storage of solvent-treated powders up to 3 months, the activity of proteases reduced in all the solvent-treated samples highest being in acetone-treated powder.