Search results for "Organic Compounds"

Theoretical study of the electronic spectrum of p-benzoquinone

1999

The electronic excited states of p-benzoquinone have been studied using multiconfigurational second-order perturbation theory (CASPT2) and extended atomic natural orbital (ANO) basis sets. The calculation of the singlet–singlet and singlet–triplet transition energies comprises 19 valence singlet excited states, 4 valence triplet states, and the singlet 3s,3p, and 3d members of the Rydberg series converging to the first four ionization limits. The computed vertical excitation energies are found to be in agreement with the available experimental data. Conclusive assignments to both valence and Rydberg states have been performed. The main features of the electronic spectrum correspond to the π…

Theoretical characterization of the lowest-energy absorption band of pyrrole

2002

The lowest-energy band of the electronic spectrum of pyrrole has been studied with vibrational resolution by using multiconfigurational second-order perturbation theory (CASPT2) and its multistate extension (MS–CASPT2) in conjunction with large atomic natural orbital-type basis sets including Rydberg functions. The obtained results provide a consistent picture of the recorded spectrum in the energy region 5.5–6.5 eV and confirm that the bulk of the intensity of the band arises from a ππ∗ intravalence transition, in contradiction to recent theoretical claims. Computed band origins for the 3s,3p Rydberg electronic transitions are in agreement with the available experimental data, although new…

Volatile components from aerial parts of Centaurea gracilenta and C. ovina ssp. besserana growing wild in Bulgaria

2011

The essential oils of Centaurea gracilenta Velen. (CG) and C. ovina Pall. ex Willd. ssp. besserana (DC.) Dostál (COB) growing wild in Bulgaria, were studied by GC and GC-MS. Forty-five compounds for CG, representing the 90.1% of the oil, and 68 compounds for COB, representing the 91.9% of the oil, were identified. The oils were rich in sesquiterpenoids (33.4% for CG and 27.3% for COB), hydrocarbons (28.3% for CG and 10.7% for COB) and carbonylic compounds (12.7% for CG and 13.1% for COB). Fatty acids were abundant only for COB (31.3%). beta-Eudesmol (12.8%), nonacosane (11.8%) and p-vinyl guiacol (7.5%) were recognized as the main constituents for CG, while hexadecanoic acid (21.4%), spathu…

Evaluation of the variations in chemical and microbiological properties of the sourdoughs produced with selected lactic acid bacteria strains during …

2022

This research aimed to analyze variations in chemical properties, microbiological characteristics and generated volatile organic compounds (VOCs) profile during sourdough fermentation. Sourdoughs were collected from different cities in Turkey at two different times and lactic acid bacteria (LAB) in the samples were identified with culture-independent and culture-dependent molecular methods. According to culture-dependent methodology, thirteen LAB species were identified. Lactobacillus spp. were identified as the major group according to MiSeq Illumina analysis. Technological potential of commonly isolated LAB species was evaluated. Due to high frequency of isolation, Fructilactobacillus san…

Multi-omics of Pseudoalteromonas haloplanktis TAC125: a quest for antimicrobial metabolic pathways

Backgrounds The Antarctic strain Pseudoalteromonas haloplanktis TAC125 is one of the model organisms of cold-adapted bacteria and is currently exploited as a new alternative expression host for numerous biotechnological applications. Interestingly, this bacterium has been reported to be able to inhibit the growth of Burkholderia cepacia complex (Bcc) strains, opportunistic pathogens responsible for the infection of immune-compromised patients. Most likely, this occurs through the synthesis of several different compounds, including Volatile Organic Compounds (VOCs), whose nature and characteristics are currently mostly unknown. Objectives To obtain a complete picture of cellular processes di…

Volatile organic compounds in truffle (Tuber magnatum Pico): Comparison of samples from different regions of Italy and from different seasons

2015

AbstractIn this paper volatile organic compounds (VOCs) from Tuber magnatum fruiting bodies were analyzed using a PTR-TOF-MS instrument. The aim was to characterize the VOC's profile of the fruiting bodies and identify if any VOCs were specific to a season and geographical areas. Multiple factorial analysis (MFA) was carried out on the signals obtained by MS. Experiments using ITS region sequencing proved that the T. magnatum life cycle includes the formation of fruiting bodies at two different times of the year. The VOCs profiles diverge when different seasonal and geographical productions are considered. Using PTR-TOF-MS, compounds present at levels as low pptv were detected. This made it…

Impact of a minimally processing route for the production of infant formulas on the organoleptic properties

2022

Many new-borns are fed with substitutes of breast milk. These products undergo several heat treatments, necessary to insure their microbiologic safety but probably modifying their organo-leptic properties. High temperature can damage milk proteins and form Maillard reaction prod-ucts with lactose. Microfiltration – to replace the heat treatments for a milk debacterization – combined with a soft spray-drying is currently an alternative little exploited to produce infant formulas (IFs) although microbiologically safe. The aim of this study was to determine the im-pact of such processing route on the organoleptic properties of the IFs. Three experimental IFs were manufactured at a semi-industr…

Persistence of a mixed lactic acid bacterial starter culture during lysine fortification of sourdough breads by addition of pistachio powder

2020

Abstract Pistachio powder was added to flour or semolina to evaluate its contribution to increase the amount of lysine in bread. Bread production was carried out by sourdough technology using a selected 3-species (Lactobacillus sanfranciscensis/Leuconostoc citreum/Weissella cibaria) lactic acid bacterial (LAB) starter culture. All sourdoughs were subjected to a long-time fermentation (21 h) and showed levels of LAB around 109 CFU/g, indicating the suitability of pistachio powder for lactic fermentation. Yeasts were also detected, in particular in semolina trials. MiSeq Illumina technology was applied to investigate the bacterial composition of sourdoughs evidencing a different distribution …

Diversity and technological potential of lactic acid bacteria of wheat flours

2013

Abstract Lactic acid bacteria (LAB) were analysed from wheat flours used in traditional bread making throughout Sicily (southern Italy). Plate counts, carried out in three different media commonly used to detect food and sourdough LAB, revealed a maximal LAB concentration of approximately 4.75 Log CFU g−1. Colonies representing various morphological appearances were isolated and differentiated based on phenotypic characteristics and genetic analysis by randomly amplified polymorphic DNA (RAPD)-PCR. Fifty unique strains were identified. Analysis by 16S rRNA gene sequencing grouped the strains into 11 LAB species, which belonged to six genera: Enterococcus, Lactobacillus, Lactococcus, Leucono…

Effects of different yeast strains, nutrients and glutathione-rich inactivated yeast addition on the aroma characteristics of Catarratto wines

2021

Catarratto is one of the most common non-aromatic white grape varieties cultivated in Sicily (Southern Italy). In order to improve the aromatic expression of Catarratto wines a trial was undertaken to investigate the effect of yeast strain, nutrition and reduced glutathione. Variables included two Saccharomyces cerevisiae strains, an oenological strain (GR1) and one isolated from honey by-products (SPF52), three different nutrition regimes (Stimula Sauvignon Blanc™ (SS), Stimula Chardonnay™ (SC) and classic nutrition practice), and a specific inactivated yeast rich in reduced glutathione to prevent oxidative processes [Glutastar™ (GIY)] ensuing in ten treatments (T1-T10). Microbiological an…