Influence of storage on volatile profiles in roasted almonds (Prunus dulcis)

Hexanal, peroxide value, and lipid hydroperoxides are common indicators of lipid oxidation in food products. However, these markers are not always reliable as levels are dynamic and often can be detected only after significant oxidation has occurred. Changes in the volatile composition of light- and dark-roast almonds were evaluated during storage over 24 weeks at 25 or 35 °C using headspace solid phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS). Several volatile changes were identified in association with early oxidation events in roasted almonds. Hexenal decreased significantly during the first 6 weeks of storage and did not increase above initial levels until 20-24 weeks of storage depending upon the degree of roast. In contrast, levels of 1-heptanol and 1-octanol increased at 16-20 weeks, depending upon the degree of roast, and no initial losses were observed. Seventeen new compounds, absent in raw and freshly roasted almonds but detectable after 6 weeks of storage, were identified. Of these, 2-octanone, 2-nonanone, 3-octen-2-one, 2-decanone, (E)-2-decenal, 2,4-nonadienal, pentyl oxirane, and especially acetic acid increased significantly (that is, >10 ng/g). The degree of roasting did not correlate with the levels of these compounds. Significant decreases in roasting-related aroma volatiles such as 2-methylbutanal, 3-methylbutanal, furfural, 2-phenylacetaldehyde, 2,3-butanedione, 2-methylpyrazine, and 1-methylthio-2-propanol were observed by 4 weeks of storage independent of the degree of roast or storage conditions.

Volatile Profiling of Pleurotus eryngii and Pleurotus ostreatus Mushrooms Cultivated on Agricultural and Agro-Industrial By-Products

The influence of genetic (species, strain) and environmental (substrate) factors on the volatile profiles of eight strains of Pleurotus eryngii and P. ostreatus mushrooms cultivated on wheat straw or substrates enriched with winery or olive oil by products was investigated by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). Selected samples were additionally roasted. More than 50 compounds were determined in fresh mushroom samples, with P. ostreatus presenting higher concentrations but a lower number of volatile compounds compared to P. eryngii. Roasting resulted in partial elimination of volatiles and the formation of pyrazines, Strecker aldehydes and sulfur compounds. Principal component analysis on the data obtained succeeded to discriminate among raw and cooked mushrooms as well as among Pleurotus species and strains, but not among different cultivation substrates. Ketones, alcohols and toluene were mainly responsible for discriminating among P. ostreatus strains while aldehydes and fatty acid methyl esters contributed more at separating P. eryngii strains.

Comparison of Automated Extraction Techniques for Volatile Analysis of Whole Milk Powder

Volatile profiling of whole milk powder is valuable for obtaining information on product quality, adulteration, legislation, shelf life, and aroma. For routine analysis, automated solventless volatile extraction techniques are favored due their simplicity and versatility, however no single extraction technique can provide a complete volatile profile due to inherent chemical bias. This study was undertaken to compare and contrast the performance of headspace solid phase microextraction, thermal desorption, and HiSorb (a sorptive extraction technique in both headspace and direct immersion modes) for the volatile analysis of whole milk powder by gas chromatography mass spectrometry. Overall, 85 unique volatiles were recovered and identified, with 80 extracted and identified using a non-polar gas chromatography column, compared to 54 extracted, and identified using a polar gas chromatography column. The impact of salting out was minimal in comparison to gas chromatography column polarity and the differences between the extraction techniques. HiSorb extracted the most and greatest abundance of volatiles, but was heavily influenced by the number and volume of lactones extracted in comparison to the other techniques. HiSorb extracted significantly more volatiles by direct immersion than by headspace. The differences in volatile selectivity was evident between the techniques and highlights the importance of using multiple extraction techniques in order to obtain a more complete volatile profile. This study provides valuable information on the volatile composition of whole milk powder and on differences between extraction techniques under different conditions, which can be extrapolated to other food and beverages.

Submerged Cultivation of Pleurotus sapidus with Molasses: Aroma Dilution Analyses by Means of Solid Phase Microextraction and Stir Bar Sorptive Extraction

The basidiomycete Pleurotus sapidus (PSA) was grown in submerged cultures with molasses as substrate for the production of mycelium as a protein source for food applications. The volatilomes of the substrate, the submerged culture, and the mycelia were analyzed by gas chromatography-tandem mass spectrometry-olfactometry. For compound identification, aroma dilution analyses by means of headspace solid phase microextraction and stir bar sorptive extraction were performed via variation of the split vent flow rate. Among the most potent odorants formed by PSA were arylic compounds (e.g., p-anisaldehyde), unsaturated carbonyls (e.g., 1-octen-3-one, ( E)-2-octenal, ( E, E)-2,4-decadienal), and cyclic monoterpenoids (e.g., 3,9-epoxy- p-menth-1-ene, 3,6-dimethyl-3a,4,5,7a-tetrahydro-1-benzofuran-2(3 H)-one). Several compounds from the latter group were described for the first time in Pleurotus spp. After separation of the mycelia from the medium, the aroma compounds were mainly enriched in the culture supernatant. The sensory analysis of the mycelium correlated well with the instrumental results.

Monitoring of priority pollutants chlorophenols in water and milk by headspace solid-phase microextraction based on electrospun polycaprolactam nanofibers decorated with cadmium oxide-carbon nanotubes

Priority pollutants chlorophenols are broadly used chemicals that are persistent in the environment and causing serious human health hazards. The current study introduces a novel adsorbent for the extraction of chlorophenols from river water, surface water, and milk by headspace solid-phase microextraction coupled with gas chromatography. The adsorbent composite was prepared by blending polycaprolactam (nylon-6) mat and newly synthesized carbon nanotubes decorated with cadmium oxide nanoparticles followed by electrospinning technique to produce based nanofiber. The proposed nanofiber was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The main parameters that affect extraction efficiency, including ionic strength, extraction time, desorption time, and extraction temperature, were investigated and optimized. The linear range was 0.05-5 ng/mL; the limits of detection (signal/noise=3) were 0.02-0.04 ng/mL. The relative recoveries for real samples (river water, surface water, and milk) were in the range of 84-114%.

Characterization of essential oils and volatiles from the aerial parts of Mentha pulegium L. (Lamiaceae) using microwave-assisted hydrodistillation (MAHD) and headspace solid phase microextraction (HS-SPME) in combination with GC-MS

Herein, the chemical profiles of the essential oils and volatiles obtained from the aerial parts of Mentha pulegium L. (Lamiaceae) are reported respectively using microwave-assisted hydrodistillation (MAHD) and headspace solid phase microextraction (HS-SPME) approaches associated to gas chromatography-mass spectrometric (GC-MS) quantification. Using MAHD-GC-MS and HS-SPME-GC-MS techniques, 30 and 28 constituents were screened in the essential oils and volatiles of M. pulegium L. aerial parts with high prevalence of oxygenated monoterpenes and non-terpene hydrocarbons, respectively. Accordingly, in the characterized chemical profiles, carvone was found to constitute about 56.0% of the oil using the former technique (MAHD), whereas oleic acid (20.1%), carvone (17.7%) along with limonene (16.1%) were found as the major constituent components of the volatile profile using the latter approach (SPME). The two methods might be used in combination to obtain a wider set of information about the chemical composition of one specific plant sample.

Volatile Terpenes and Terpenoids from Workers and Queens of Monomorium chinense (Hymenoptera: Formicidae)

Twenty-one volatile terpenes and terpenoids were found in Monomoriumchinense Santschi (Hymenoptera: Formicidae), a native Chinese ant, by using headspace solid-phase microextraction (HS-SPME) coupled with gas-phase chromatography and mass spectrometry (GC-MS), which makes this ant one of the most prolific terpene producers in insect. A sesquiterpene with unknown structure (terpene 1) was the main terpene in workers and neocembrene in queens. Terpenes and terpenoids were detected in poison, Dufour’s and mandibular glands of both workers and queens. Worker ants raised on a terpene-free diet showed the same terpene profile as ants collected in the field, indicating that denovo terpene and terpenoid synthesis occurs in M. chinense.

Reducing off-Flavour in Commercially Available Polyhydroxyalkanoate Materials by Autooxidation through Compounding with Organoclays

Polyhydroxyalkanoates (PHAs) are nowadays considered competent candidates to replace traditional plastics in several market sectors. However, commercial PHA materials exhibit unsatisfactory smells that can negatively affect the quality of the final product. The cause of this typical rancid odour is attributed to oxidized cell membrane glycolipids, coming from Gram-negative production strains, which remain frequently attached to PHAs granules after the extraction stage. The aim of this research is the development of customised PHA bio-nano-composites for industrial applications containing organomodified nanoclays with high adsorbance properties able to capture volatile compounds responsible for the displeasing fragrance. To this end, a methodology for the detection and identification of the key volatiles released due to oxidative degradation of PHAs has been established using a headspace solid-phase microextraction technique. We report the development of nine bio-nano-composite materials based on three types of commercial PHA matrices loaded with three species of nanoclays which represent a different polar behaviour. It has been demonstrated that although the reached outcoming effect depends on the volatile nature, natural sepiolite might result in the most versatile candidate for any the PHA matrices selected.

Volatile profiles of flavedo, pulp and seeds in Poncirus trifoliata fruits

BACKGROUND

Poncirus trifoliata, also known as trifoliate orange, is a tree native to China and Korea and widely used all over the world as a rootstock breeding material. In this study the differences among the volatile profiles of flavedo, pulp and seeds from two cultivars (var. trifoliata and var. monstrosa) grown in Italy (Marche, Abruzzo and Sicily) were determined. Headspace solid phase microextraction and hydrodistillation techniques were used in combination with GC/FID and GC/MS to obtain the volatile profiles of the samples.

RESULTS

Both techniques permitted the differentiation of fruit parts based on the main volatile components: the flavedo was characterized by monoterpene hydrocarbons such as limonene and myrcene, the seeds were characterized by sesquiterpene hydrocarbons such as (E)-caryophyllene and germacrene D, while the pulp showed an intermediate composition. The main differences in volatile profiles obtained by the two techniques were analyzed by chemometric techniques such as principal component analysis.

CONCLUSION

The study did not highlight significant differences in volatiles between the two cultivars of trifoliate orange, while few differences in the number of volatiles in the fruit parts were revealed by the two techniques.

Sugars Replacement as a Strategy to Control the Formation of α-Dicarbonyl and Furanic Compounds during Cookie Processing

In the last decade, several preventive strategies were considered to mitigate the chemical hazard accumulation in food products. This work aimed to study the effect of different sugars on the development of the main chemical hazard in cookies. For this purpose, model biscuits prepared using sucrose, fructose, and glucose were baked at different temperatures (150, 170, and 190 °C) and for different times (from 5 to 45 min), and the levels of α-dicarbonyl compounds, such as 3-deoxyglucosone (3-DG), glyoxal (GO) and methylglyoxal (MGO), 5-hydroxymethylfurfural (HMF), and furanic aromatic compounds were monitored. The replacement of sucrose in the cookie recipes with monosaccharides had as a consequence the highest accumulation of 3-DG (200-600 times higher), MGO, HMF, and furanic volatile compounds, while the use of sucrose allowed for maintaining the 3-DG, MGO, and HMF levels at less than 10 mg/kg dry matter in cookies for the estimated optimal baking time. Moreover, cookies with sucrose were characterised in terms of volatile compounds, mainly in terms of lipid oxidation products, while cookies with fructose or glucose baked at the highest temperature were characterised almost exclusively by Maillard reaction products, confirming a faster development of this reaction during baking at the studied temperatures.

Presence of monoterpene synthase in four Labiatae species and Solid-Phase Microextraction- Gas chromatography-Mass Spectroscopy analysis of their aroma profiles

Background:

The family Lamiaceae (Labiatae) has included some medicinal plants. some monoterpene synthases, including linalool and limonene synthases, have been cloned and functionally characterized from several plants of Labiatae family.

Materials and Methods:

In this study, presence of linalool and limonene synthases, in four species of Labiatae family including Nepeta cataria, Lavandula angustifolia, Hyssopus officinalis and Salvia sclarea has been determined by molecular biological techniques together with the Head space SPME – GC-MS analysis of the aroma profile of these species.

Results:

Indicated that none of the plant species produced distinguishable bands with primer pairs related to d-limonene synthase. Distinguishable bands around 1800 bp in cDNA samples of L. angustifolia, H. officinalis and S. sclarea were observed regarding to the presence of linalool synthase. Head space SPME-GC-MS analysis of the aroma profiles of the above-mentioned plants showed that linalool (31.0%), linalyl acetate (18.2%), were found as the major compounds of L. angustifolia, while geraniol (5.5%), nerol (34.0%) and α- citral (52.0%) were identified as the main compounds of the N. cataria. The major components of H. officinalis and S. sclarea oils were determined as cis-pinocamphone (57.3%), and linalool (19.0%), linalyl acetate (51.5%), respectively.

Conclusion:

H. officinalis was rich of cyclic monoterpenes, L. angustifolia, N. cataria and S. sclarea showed considerable amount of linear monoterpenes. The aroma profile of the above-mentioned plants contained low concentration of sesquiterpenes except N. cataria, which indicated no sesquiterpene. The profiles of the main components of these plants are in agreement with molecular assays.

In vitro study of the binding between chlorpyrfos and sex hormones using headspace solid-phase microextraction combined with high-performance liquid chromatography: A new aspect of pesticides and breast cancer risk

Endocrine-disrupting chemicals are compounds that alter the normal functioning of the endocrine system. Organophosphorus insecticides, as chlorpyrifos (CPS), receive an increasing consideration as potential endocrine disrupters. Physiological estrogens, including estrone (E1), 17β-estradiol (E2), and diethylstilbestrol (DES) fluctuate with life stage, suggesting specific roles for them in biological and disease processes. There has been great interest in whether certain organophosphorus pesticides can affect the risk of breast cancer. An understanding of the interaction processes is the key to describe the fate of CPS in biological media. The objectives of this study were to evaluate total, bound, and freely dissolved amount of CPS in the presence of three estrogenic sex hormones (ESHs). In vitro experiments were conducted utilizing a headspace solid phase microextraction (HS-SPME) combined with high-performance liquid chromatography (HPLC) method. The obtained Scatchard plot based on the proposed SPME-HPLC method was employed to determine CPS-ESHs binding constant and the number of binding sites as well as binding percentage of each hormone to CPS. The number of binding sites per studied hormone molecule was 1.10, 1, and 0.81 for E1, E2, and DES, respectively. The obtained results confirmed that CPS bound to one class of binding sites on sex hormones.

Characteristic Volatile Composition of Seven Seaweeds from the Yellow Sea of China

Plant volatile organic compounds (VOCs) represent a relatively wide class of secondary metabolites. The VOC profiles of seven seaweeds (Grateloupia filicina, Polysiphonia senticulosa, Callithamnion corymbosum, Sargassum thunbergii, Dictyota dichotoma, Enteromorpha prolifera and Ulva lactuca) from the Yellow Sea of China were investigated using multifiber headspace solid phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC–MS), among them, the VOCs of three red algae Grateloupia filicina, Polysiphonia senticulosa, and Callithamnion corymbosum were first reported. Principal component analysis (PCA) was used to disclose characteristic categories and molecules of VOCs and network pharmacology was performed to predict potential biomedical utilization of candidate seaweeds. Aldehyde was found to be the most abundant VOC category in the present study and (E)-β-ionone was the only compound found to exist in all seven seaweeds. The chemical diversity of aldehydes in E. prolifera suggest its potential application in chemotaxonomy and hinted that divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber is more suitable for aldehyde extraction. VOCs in D. dichotoma were characterized as sesquiterpenes and diterpenes and the most relevant pharmacological pathway was the neuroactive ligand–receptor interaction pathway, which suggests that D. dichotoma may have certain preventive and therapeutic values in cancer, especially in lung cancer, in addition to neuropsychiatric diseases.

E-Nose and HS-SPME-GC-MS unveiling the scent signature of Ligusticum chuanxiong and its medicinal relatives

Introduction

To explore the origin and evolution of Ligusticum Chuanxiong, we conducted a component analysis of Ligusticum Chuanxiong and its medicinal relatives.

Methods

This study encompassed seven species from various origins, including Chuanxiong (Ligusticum chuanxiong Hort.), Gansu Chuanxiong (Ligusticum chuanxiong cv. Gansu), Yunnan Chuanxiong (Ligusticum chuanxiong cv. Yunnan), Japanese Chuanxiong (Cnidium officinale Makino), Fuxiong (Ligusticum sinense 'Fuxiong'), Gaoben (Ligusticum sinense), and Liaogaoben (Ligusticum jeholense), comprising 27 distinct materials. We employed headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) to identify various odor profiles from these species using electronic nose technology (E-nose). The method effectively identified volatile constituents in the leaves of these seven species.

Results

Results indicated that odor differences between L. chuanxiong and its medicinal relatives were predominantly observed in sensors W1W and W1S. Linear discriminant factor analysis (LDA) successfully distinguished five of the relatives; however, L. chuanxiong and L. sinense exhibited high odor similarity, limiting complete differentiation in some samples. HS-SPME-GC-MS identified a total of 118 volatile constituents, with eight differential volatiles identified: trans-Neocnidilide, β-Caryophyllene, β-Selinene, 5-Pentylcyclohexa-1,3-diene, (E)-Ligustilide, Butylphthalide, Neophytadiene, and Senkyunolide. Hierarchical cluster analysis (HCA) grouped L. chuanxiong, L. sinense, L. jeholense, and L. chuanxiong cv. Gansu together, highlighting the close relationship between L. chuanxiong and L. sinense. Joint analysis revealed a significant positive correlation between sensor W1W and the differential volatile component β-Caryophyllene, suggesting its potential for distinguishing closely related species.

Discussion

This study provides a foundational understanding of volatile components in the leaves of L. chuanxiong and its medicinal relatives using E-nose combined with HS-SPME-GC-MS, contributing to the discussion on their interspecific odor characteristics and relationships.

Identification of potent odorants in a novel nonalcoholic beverage produced by fermentation of wort with shiitake (Lentinula edodes)

Novel refreshments with pleasant flavors were developed by fermentation of wort with basidiomycetes. Among 31 screened fungi, shiitake (Lentinula edodes) produced the most pleasant flavor. It was perceived as fruity, slightly sour, and plum-like. Flavor compounds were isolated by liquid-liquid extraction (LLE) and by headspace solid phase microextraction (HS-SPME). The key odor-active compounds were analyzed by a gas chromatography system equipped with a tandem mass spectrometry detector and an olfactory detection port (GC-MS/MS-O) and aroma extract dilution analysis (AEDA). For HS-SPME, a revised method of increasing the GC inlet split ratio was used. Most of the key odor-active compounds (e.g., 2-acetylpyrrole, β-damascenone, (E)-2-nonenal, and 2-phenylethanol) were detected with both extraction techniques. However, distinct differences between these two methods were observed.

l-Serine is the Direct Precursor for the Pyrazine Ring Construction in the Biosynthesis of 3-Isobutyl-2-Methoxypyrazine in Bell Pepper Fruits (Capsicum annuum L.)

3-Isobutyl-2-methoxypyrazine (IBMP) is an extremely potent odorant and responsible for the specific aroma of many fruits and vegetables. Especially bell pepper contains high levels of IBMP, which is the character impact compound of its typical aroma. However, since the discovery of methoxypyrazines in plants in the 1960s the biosynthesis of their pyrazine ring motif remained so far unknown. Therefore, the biosynthetic pathway to IBMP was investigated by feeding experiments with stable-isotope labeled precursors. For the first time it could be shown that l-serine plays a key role in the pyrazine ring construction of 3-alkyl-2-methoxypyrazines (MPs). Based on HS-SPME-GCxGC-TOF-MS analysis, it is shown that the biosynthetic pathway to IBMP is closely linked to photorespiratory derived l-serine.