Effect of Soil Composition on Secondary Metabolites of Moroccan Saffron (Crocus sativus L.).

Climate and soil are important factors that affect the quality of saffron. Saffron quality is determined by the marked content of secondary metabolites. The objective of this work was to study the effect of soil physicochemical properties on the secondary metabolites of saffron. Our study concerned the analysis of saffron samples by high-performance liquid chromatography-detection by diode array (HPLC-DAD). Soil samples were analyzed by physicochemical methods, ED-XRF fluorescence and X-ray diffraction to determine the different types of clays. Saffron samples grown in loam-clay-sand soils contained high values of crocins and kaempferol 3-sophoroside 7-glucoside but low values of safranal. In addition, saffron samples grown in soils rich in organic matter, phosphorus and potassium contained high values of crocins and kaempferol 3-sophoroside 7-glucoside but low values of safranal. This original approach was carried out for the first time in our study, both by ED-XRF fluorescence and by X-ray diffraction, to determine what elements affect the quality of saffron. Thus, we concluded that clays containing low amounts of iron could have a positive effect on the coloring strength of saffron.

Determination of Saffron Volatiles by HS-SBSE-GC in Flavored Cured Ham.

At present, the development of new agri-food products, including flavored meat products presented in ready-to-eat vacuum packs, is encouraged. The addition of ingredients used as flavoring agents creates the need to be able to determine the volatile compounds responsible for their characteristic aroma. The aim of this study is to propose, develop, and validate a new method that uses headspace-stir bar sorptive extraction-gas chromatography/mass spectrometry (HS-SBSE-GC/MS) to determine the saffron aroma in cured ham flavored with this spice. Results showed that safranal was the main volatile compound that could be identified and quantified in cured ham flavored with saffron. This analytical method was adequate in terms of linearity, selectivity, sensitivity, and accuracy. To our knowledge, this is the first time that an HS-SBSE-GC/MS method for determining the saffron aroma of flavored cured ham has been developed and validated, and it is of interest to agri-food industries.

Effect of Crocus sativus L. Stigmas Microwave Dehydration on Picrocrocin, Safranal and Crocetin Esters.

The dehydration process is the basis to obtain high quality saffron and to preserve it for a long time. This process modifies saffron's main metabolites that define its quality, and are responsible for the characteristic color, taste, and aroma of the spice. In this work, the effect of microwave dehydration on saffron main metabolites (picrocrocin, safranal and crocetin esters) from Crocus sativus L. stigmas at three determinate powers and different time lapses was evaluated. The results showed that this dehydration process obtained similar or lower crocetin esters content, and after three months of storage, higher concentration was shown in treatments at 440 W for 36 s, 55 s, and 73 s; at 616 W for 90 s; and at 800 W for 20 s. Picrocrocin content was lower and safranal content was higher in all treatments compared to the control both before and after storage. Regarding to commercial quality, microwave dehydration obtained Category I of saffron according to International Standard Organization (ISO) 3632. After three months of storage, treatments at 616 W for 83 s and 800 W for 60 s obtained lower categories. The results obtained suggest that microwave dehydration is a suitable process for obtaining high quality saffron, 800 W with 6 lapses of 20 s being the best conditions studied.

Impact of two different dehydration methods on saffron quality, concerning the prevalence of Saffron latent virus (SaLV) in Iran.

The dehydration process is a prerequisite to preserve saffron for a long time. According to this process, saffron shows differences in the main compounds responsible for its quality (colour, taste, aroma, and flavonol content). At present, the freeze-drying method obtains dried products with the highest quality. Viruses can modify the physiology and metabolism of plants, being able to affect the activities of several enzymes. For this reason, the main compounds of saffron have been analyzed under two different dehydrating processes, freeze-drying and dark-drying, considering their infection status with the Saffron latent virus (SaLV). Results showed that the picrocrocin and safranal content enables to differ dark-dried samples from freeze-dried ones. Besides, the kaempferol-3-O-sophoroside-7-O-glucoside content allows differentiating between SaLV-infected (SaLV+) and uninfected (SaLV-) saffron samples. Moreover, our data suggest that the freeze-drying would decrease crocins content, and dark-drying can nullify the adverse effect of SaLV on crocins content.

Development and validation of an HPLC-DAD method for determination of oleuropein and other bioactive compounds in olive leaf by-products.

BACKGROUND: Oil mills could benefit by preparing their own aqueous extracts from olive leaves. Accordingly, the present study aimed to measure the bioactive compounds richness of such extracts, especially oleuropein. A water-based microwave extraction procedure was developed and a selective and precise high-performance liquid chromatography with diode array detection (HPLC-DAD) method was validated for the determination of oleuropein and others bioactive compounds from olive leaves. RESULTS: The water solubility of oleuropein was determined to be 9.5 g L-1 . The extraction procedure was optimized in terms of power, olive leaf weight/water volume ratio and time of extraction, and the results revealed that 2 mg mL-1 and a microwave irradiation at 800 W for 30 s resulted in the greatest efficiency. Oleuropein was determined by the new validation method, which showed good linearity (r2 = 0.996), precision (% relative standard deviation < 10%), recovery (118.6%), and limits of detection (17.48 mg L-1 ) and quantification (21.54 mg L-1 ). Good correlation (r2 = 0.979) was obtained between oleuropein of the olive leaf extracts determined by HPLC-DAD and by UV-visible spectrophotometry. CONCLUSION: A simple extraction method was developed and validated to obtain aqueous extract from olive leaves by microwave extraction, determining for the first time oleuropein water solubility. Validation of the method showed that oleuropein in olive leaves could be quantified when it is at least 1% of dry weight by means of HPLC-DAD. UV-visible spectrophotometry can be useful in oil mills because it enables the content of oleuropein and other bioactive compounds content to be determined in situ in such leaf aqueous extracts. © 2020 Society of Chemical Industry.

Bioactivity and Bioavailability of the Major Metabolites of Crocus sativus L. Flower.

Crocus sativus L. has been cultivated throughout history to obtain its flowers, whose dried stigmas give rise to the spice known as saffron. Crocetin esters, picrocrocin, and safranal are the main metabolites of this spice, which possess a great bioactivity, although the mechanisms of action and its bioavailability are still to be solved. The rest of the flower is composed by style, tepals, and stamens that have other compounds, such as kaempferol and delphinidin, which have an important antioxidant capacity, and these can be applied in foods, phytopharmaceuticals, and cosmetics. The aim of this work was to provide an updated and critical review of the research on the main compounds of Crocus sativus L. flower, including the adequate analytical methods for their identification and quantification, with a focus on their bioactivity and bioavailability.

Kinetics of polyphenol content of dry flowers and floral bio-residues of saffron at different temperatures and relative humidity conditions.

The cultivation of Crocus sativus L. is valued for its dried stigmas, but the rest of the parts of its flowers are increasingly important. Saffron flowers (SF) are natural sources of antioxidant compounds. Kaempferols and anthocyanins are the main compounds of the high-phenolic content of SF. This work studies the evolution of flavonols and anthocyanins of dry SF and floral bio-residues of saffron (FBR) and their kinetics at different temperatures and relative humidity (RH) conditions. There was a degradation process of anthocyanins that fitted a second-order kinetic model and kaempferols showed better fit in a first-order kinetics model. The best storage conditions for anthocyanins studied in SF and FBR was 25 °C and 23% RH. The main kaempferol (Kaempferol 3-O-sophoroside) was no deteriorated in FBR. These results could contribute to the using SF and FBR as food and active ingredients in cosmetic industry, as well as development of new food products.

Fast methodology of analysing major steviol glycosides from Stevia rebaudiana leaves.

The aim of this work is to propose an HPLC method for analysing major steviol glycosides as well as to optimise the extraction and clarification conditions for obtaining these compounds. Toward this aim, standards of stevioside and rebaudioside A with purities ⩾99.0%, commercial samples from different companies and Stevia rebaudiana Bertoni leaves from Paraguay supplied by Insobol, S.L., were used. The analytical method proposed is adequate in terms of selectivity, sensitivity and accuracy. Optimum extraction conditions and adequate clarification conditions have been set. Moreover, this methodology is safe and eco-friendly, as we use only water for extraction and do not use solid-phase extraction, which requires solvents that are banned in the food industry to condition the cartridge and elute the steviol glycosides. In addition, this methodology consumes little time as leaves are not ground and the filtration is faster, and the peak resolution is better as we used an HPLC method with gradient elution.

Volatile compounds formation in alcoholic fermentation from grapes collected at 2 maturation stages: influence of nitrogen compounds and grape variety.

The aim of this work was to study the influence of nitrogen compounds on the formation of volatile compounds during the alcoholic fermentation carried out with 4 nonaromatic grape varieties collected at 2 different maturation stages. To do this, Monastrell, Merlot, Syrah, and Petit Verdot grapes were collected 1 wk before harvest and at harvest. Then, the musts were inoculated with the same Saccharomyces cerevisiae yeast strain and were fermented in the same winemaking conditions. Amino acids that showed the highest and the lowest concentration in the must were the same, regardless of the grape variety and maturation stage. Moreover, the consumption of amino acids during the fermentation increased with their concentration in the must. The formation of volatile compounds was not nitrogen composition dependent. However, the concentration of amino acids in the must from grapes collected 1 wk before harvest can be used as a parameter to estimate the concentration of esters in wines from grapes collected at harvest and therefore to have more information to know the grape oenological capacity. Application of principal components analysis (PCA) confirmed the possibility to estimate the concentration of esters in the wines with the concentration of nitrogen compounds in the must.

Study of the evolution of nitrogen compounds during grape ripening. application to differentiate grape varieties and cultivated systems.

The aim of this work was to study the evolution of amino acids and ammonium during grape ripening and to evaluate its application to differentiate grape varieties and cultivated systems (organic and nonorganic). For this purpose, Monastrell, Syrah, Merlot, and Petit Verdot grapes produced using conventional agriculture and Monastrell grape cultivated using organic agriculture, collected during two consecutive harvests at different stages of ripening, were studied. These years of harvest were very different climatic years; even so, the grape varieties presented similar qualitative compositions. Therefore, the percentage of amino acids at harvest moment allowed differentiation of grapes according to variety and cultivated system, regardless of the year. The nitrogen composition could allow estimation of the fermentative aroma potential of grapes. Thus, Syrah was the grape with the greatest aroma potential at harvest. Monastrell nonorganic grape had a concentration of nitrogen compounds superior to that of Monastrell organic grape. In Monastrell, Syrah, and Merlot, traditional varieties in the area, the highest concentration of nitrogen compounds coincided with the highest degrees Baume/total acidity ratio and color index during 2007. Consequently, technological and phenolic maturity of these grape varieties coincided with the maximum composition of nitrogen compounds. However, in 2008, this did not happen because grape ripening was irregular as a consequence of different climatological conditions.

Non-destructive method to determine halophenols and haloanisoles in cork stoppers by headspace sorptive extraction.

The new solvent-free technique called headspace sorptive extraction (HSSE) was used to determine 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, 2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole, 2,4,6-tribromoanisole, pentachloroanisole in cork stoppers, without grinding them, as these may be responsible for the cork taint off-flavour in wine. The best HSSE sorption kinetics for the target analytes were obtained after submitting the spiked corks to 100 degrees C for 1h, followed by a 30 min stabilization time at room temperature. The stir bar was desorbed in a thermal desorption system coupled to a gas chromatograph-mass spectrometer. The method proposed showed good linearity over the concentration range tested, 1-70 ngg(-1), and correlation coefficients ranged from 0.90 to 0.99 for all the analytes. The reproducibility and repeatability of the method were estimated between 4.91 and 12.67%. The effect of the different cork matrixes on the extraction recovery of the target compounds was studied, with the natural corks showing the higher recovery percentage in relation to agglomerate ones.

Effect of red grapes co-winemaking in polyphenols and color of wines.

The red grapes co-winemaking effect on phenolic fraction and wine color has been studied for the first time, where Monastrell was comacerated and cofermentated with Cabernet Sauvignon and Merlot. Changes in the relative abundance of anthocyanins were observed as well as hyperchromic shifts at 530 and 620 nm; these effects remain constant after aging. Co-winemaking also favored copigmentation, giving way to more stable anthocyanins and facilitating their polymerization. With regard to color evolution, the mixture of Monastrell with Merlot grapes was more appropriate than with Cabernet Sauvignon for aging wines in oak barrels. The extent of copigmentation was more important in young wines than in aged wines. This is mainly due to the self-anthocyanin monomer reactions in the case of young wines, whereas in aged wines copigmentation is mainly due to the reaction between the anthocyanins and other polyphenolic cofactors. Discriminant analysis showed the possibility of differentiating wines according to the aging time and the type of wine, with color parameters (color intensity, OD 620 nm, and OD 520 nm) being the most important discrimination variables in the first case and petunidin-3-glucoside and peonidin-3-glucoside contents in the second case.