Physicochemical, structural, and functional characterization of pectin extracted from quince and pomegranate peel: A comparative study

Pectin's physicochemical, structural, and functional characteristics vary widely depending on the source of extraction. In this study, pectins were extracted from seedless quince and pomegranate peel, and their physicochemical, structural, and functional properties were investigated. A Box-Behnken Design with three factors and three levels was applied to optimize the pectin extraction yield from each matrix. As a result, the best extraction yields for quince pectin (QP) and pomegranate peel pectin (PPP) were 11.44 and 12.08 % (w/w), respectively. Both extracted pectins exhibit a linear structure, with the homogalacturonan domain dominating the rhamnogalacturonan I. Both pectins are highly methyl-esterified (DM > 69 %) with a higher degree of acetylation for PPP than QP, with 12 and 8 %, respectively. Unlike QP, PPP has a narrow, homogenous distribution and greater molecular weight (120 kDa). Regarding functionality, 1 g of QP could retain 4.92 g of water, and both pectin emulsions were more stable at room temperature than at 4 °C. When the concentration of QP is increased, rheological measurements demonstrate that it exhibits pseudoplastic behavior. Finally, QP can be used as a thickener, whereas PPP can be utilized as starting material for chemical changes to create multifunctional pectins.

Impact of Pretreatment and Drying Factors on Chemical and Biochemical Attributes of Moroccan Thompson Seedless Grapes

Drying is a common technique in the agrifood industry, but insufficient control in the drying process can result in changes to the fruit's appearance due to physiological damage during processing. The aim of this study was to investigate the impact of pretreatment and drying process parameters on Moroccan raisins' quality and safety. The experimental levels of pretreatment factors (blanching, browning agents) and drying temperature were defined at the beginning. Subsequently, a 24-factorial design was employed to provide a simple and reliable model capable of relating directly the response factor (drying time, color intensity change (E∗), chromaticity (C∗), and browning rate) to the variables (NaOH concentration, antibrowning agent concentration, temperature, and relative humidity). All four parameters had a statistically considerable effect on studied responses. Blanching for 5 minutes at 1% of NaOH solution, using an appropriate concentration of antibrowning agent (5% Na2S2O5), and drying at 70°C with 30% of relative moisture can lead to better preservation of grapes' appearance and quality (chromaticity (C∗) and color change (E∗)). Also, in these conditions, a lower browning rate (14.48%), a lower 5-hydroxymethylfurfural content (12.40 mg/100 g DW), and a higher level of polyphenols (135.79 ± 13.17 mg GAE/100 g DW) and flavonoid content (57.81 ± 3.08 mg Qeq/100 g DW) have been recorded while meeting international standards for SO2 content and microbial quality.

Exploring the genetic and phenotypic diversity within and between onion (Allium cepa L.) ecotypes in Morocco

Background

Gaining insight into crop diversity, both at the genetic and phenotypic levels, is of prime importance for onion breeding with an enhanced yield and quality in combination with improved resistance to biotic and abiotic stresses. In the current study, 192 different onion plants, representing 16 ecotypes, were characterized using ISSR markers.

Results

Based on the ISSR marker profile, there was a clear grouping of the plants into 16 different ecotypes. Though the 16 populations originated from the same geographic region in Morocco, a significant genetic diversity was detected. After a genomic characterization, field trials in three different environments in Morocco were laid out. The phenotypic characterization showed that there were always significant differences between ecotypes, and for most traits, there was also a significant environmental effect and a significant interaction between environment and ecotype. The broad-sense heritability (H²) for the phenotypic traits associated with color (L*, a*, and b*) was the largest (84.2%, 80.6%, 79.2%), demonstrating that color is conditioned primarily by genetic factors. In contrast, the H² for yield was the lowest (41.8%), indicating that the environment has a substantial effect on yield. In addition, there was a significant association between the presence/absence of certain bands and various phenotypic traits.

Conclusion

ISSR markers are a powerful tool in distinguishing onion ecotypes. In addition, significant associations between marker scores and phenotypic traits could be detected, representing particular importance for future breeding programs.

Consolidated bioethanol production from olive mill waste: Wood-decay fungi from central Morocco as promising decomposition and fermentation biocatalysts

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First report on lignocellulolytic activity and diversity of fungi from central Morocco.

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Olive Mill Waste (OMW) is a suitable biomass for local biorefinery in Meknes region.

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Fusaria isolates produce high and diversified lignocellulases using Consolidated Bioprocess.

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Fusarium oxysporum (76) achieves 2.47 g.L⁻¹ bioethanol production and 0.84 g.g⁻¹ yield.

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Bioethanol is maximally produced during the oxygen-limiting phase.

Meknes region is a Moroccan olive-processing area generating high amounts of non-valorized Olive Mill Waste (OMW). Fungi are natural decomposers producing varied enzyme classes and effectively contributing to the carbon cycle. However, structural complexity of biomass and modest performances of wild fungi are major limits for local biorefineries. The objective of current research is to assess the ability of local fungi for bioethanol production from OMW using Consolidated Bioprocessing (CBP). This is done by characterizing lignocellulolytic potential of six wood-decay and compost-inhabiting ascomycetes and selecting potent fermentation biocatalysts. High and diversified activities were expressed by Fusarium solani and Fusarium oxysporum: 9.36 IU. mL⁻¹ and 2.88 IU. mL⁻¹ total cellulase activity, 0.54 IU. mL⁻¹ and 0.57 IU. mL⁻¹ laccase activity, respectively, and 8.43 IU. mL⁻¹ lignin peroxidase activity for the latter. F. oxysporum had maximum bioethanol production and yield of 2.47 g.L^-1 and 0.84 g.g⁻¹, respectively, qualifying it as an important bio-agent for single-pot local biorefinery.

Effect of amino acids on red pigments and citrinin production in Monascus ruber

Amino acids were used as sole nitrogen sources to examine their effects on the production of water-soluble red pigments and citrinin by Monascus ruber ATCC 96218 cultivated on chemically defined media. In general, when glycine, tyrosine, arginine, serine, or histidine were used as sole nitrogen sources, they favored the production of red pigments, and restricted the synthesis of the mycotoxin. In contrast, the production of citrinin was enhanced in media supplemented with either glutamate, alanine, or proline. Histidine was found to be the most valuable amino acid as it resulted in the highest production of red pigments and almost completely eliminated the formation of mycotoxin.

Effect of 26-oxygenosterols from Ganoderma lucidum and their activity as cholesterol synthesis inhibitors

Ganoderma lucidum is a medicinal fungus belonging to the Polyporaceae family which has long been known in Japan as Reishi and has been used extensively in traditional Chinese medicine. We report the isolation and identification of the 26-oxygenosterols ganoderol A, ganoderol B, ganoderal A, and ganoderic acid Y and their biological effects on cholesterol synthesis in a human hepatic cell line in vitro. We also investigated the site of inhibition in the cholesterol synthesis pathway. We found that these oxygenated sterols from G. lucidum inhibited cholesterol biosynthesis via conversion of acetate or mevalonate as a precursor of cholesterol. By incorporation of 24,25-dihydro-[24,25-3H2]lanosterol and [3-3H]lathosterol in the presence of ganoderol A, we determined that the point of inhibition of cholesterol synthesis is between lanosterol and lathosterol. These results demonstrate that the lanosterol 14alpha-demethylase, which converts 24,25-dihydrolanosterol to cholesterol, can be inhibited by the 26-oxygenosterols from G. lucidum. These 26-oxygenosterols could lead to novel therapeutic agents that lower blood cholesterol.

Aspergillus oryzae produces compounds inhibiting cholesterol biosynthesis downstream of dihydrolanosterol

The formation of cholesterol synthesis inhibiting molecules by five different strains of the koji mold Aspergillus oryzae was studied. After growing these strains on a complex liquid medium we found in crude organic phase extracts and specific fractions there from compounds inhibiting cholesterol synthesis in human hepatic T9A4 cells in vitro at enzyme sites downstream of dihydrolanosterol. This was evidenced by using different radioactively labeled precursors, namely acetate, mevalonate, 24,25-dihydro-[24,25-(3)H2]-lanosterol or [3-(3)H]-lathosterol.

Cholesterol-lowering properties of Ganoderma lucidum in vitro, ex vivo, and in hamsters and minipigs

INTRODUCTION

There has been renewed interest in mushroom medicinal properties. We studied cholesterol lowering properties of Ganoderma lucidum (Gl), a renowned medicinal species.

RESULTS

Organic fractions containing oxygenated lanosterol derivatives inhibited cholesterol synthesis in T9A4 hepatocytes. In hamsters, 5% Gl did not effect LDL; but decreased total cholesterol (TC) 9.8%, and HDL 11.2%. Gl (2.5 and 5%) had effects on several fecal neutral sterols and bile acids. Both Gl doses reduced hepatic microsomal ex-vivo HMG-CoA reductase activity. In minipigs, 2.5 Gl decreased TC, LDL- and HDL cholesterol 20, 27, and 18%, respectively (P < 0.05); increased fecal cholestanol and coprostanol; and decreased cholate.

CONCLUSIONS

Overall, Gl has potential to reduce LDL cholesterol in vivo through various mechanisms. Next steps are to: fully characterize bioactive components in lipid soluble/insoluble fractions; evaluate bioactivity of isolated fractions; and examine human cholesterol lowering properties. Innovative new cholesterol-lowering foods and medicines containing Gl are envisioned.

Aflatoxin genes and the aflatoxigenic potential of Koji moulds

Sixty-four Aspergillus isolates, 54 of which originated from food fermentations, and 18 Aspergillus reference strains were identified and screened for the presence of aflatoxin genes aflR and omt-1. Among the Koji moulds, not only A. oryzae but also A. flavus strains were found. Furthermore, 27% of A. oryzae and 93% of A. flavus strains lacked either aflR or both aflR- and omt-1. A selection of 29 strains was also checked for the presence of pksA and nor-1. This revealed large deletions in the aflatoxin gene cluster of some strains. The hybridisation patterns also suggested a polarity in the deletion events, originating in the vicinity of pksA and extending towards omt-1. Other strains exhibited BamHI restriction fragment length polymorphisms (RFLPs) for either aflR or for aflR and omt-1. All aflR and/or omt-1 deletion strains turned out to be unable to produce aflatoxin. The RFLP-carrying strains either produced only traces of aflatoxin or none at all. In 73% of the A. oryzae strains, no apparent deletions were detected with the aflR and omt-1 probes. Nevertheless, after incubation in aflatoxin-inducing media, no aflatoxin B1 production could be detected in those A. oryzae strains.

Lovastatin biosynthesis by Aspergillus terreus in a chemically defined medium

Lovastatin is a secondary metabolite produced by Aspergillus terreus. A chemically defined medium was developed in order to investigate the influence of carbon and nitrogen sources on lovastatin biosynthesis. Among several organic and inorganic defined nitrogen sources metabolized by A. terreus, glutamate and histidine gave the highest lovastatin biosynthesis level. For cultures on glucose and glutamate, lovastatin synthesis initiated when glucose consumption levelled off. When A. terreus was grown on lactose, lovastatin production initiated in the presence of residual lactose. Experimental results showed that carbon source starvation is required in addition to relief of glucose repression, while glutamate did not repress biosynthesis. A threefold-higher specific productivity was found with the defined medium on glucose and glutamate, compared to growth on complex medium with glucose, peptonized milk, and yeast extract.

Kinetic analysis of red pigment and citrinin production by Monascus ruber as a function of organic acid accumulation

In submerged cultures performed in synthetic medium containing glucose and glutamate, the filamentous fungus Monascus ruber produced a red pigment and a mycotoxin, citrinin. In oxygen-limiting conditions, the production of these two metabolites was growth-associated, as was the production of primary metabolites. In oxygen-excess conditions, the profile of citrinin production was typical of a secondary metabolite, since it was produced mostly during the stationary phase. In contrast, the production of the pigment decreased rapidly throughout the culture, showing a profile characteristic of an inhibitory mechanism. The organic acids produced during the culture, L-malate and succinate, were shown to be slightly inhibitory against pigment production, while citrinin production was unaffected. However, this inhibition could not account for the observed profile of pigment production in batch cultures. Other dicarboxylic acids such as fumarate or tartrate showed a similar effect to that provoked by malate and succinate as regards pigment production. It was concluded that the decrease in red pigment production during the culture was due to the inhibitory effect of an unknown product whose accumulation was favored in aerobic conditions.

Medium-chain fatty acids affect citrinin production in the filamentous fungus Monascus ruber

During submerged culture in the presence of glucose and glutamate, the filamentous fungus Monascus ruber produces water-soluble red pigments together with citrinin, a mycotoxin with nephrotoxic and hepatoxic effects on animals. Analysis of the (13)C-pigment molecules from mycelia cultivated with [1-(13)C]-, [2-(13)C]-, or [1, 2-(13)C]acetate by (13)C nuclear magnetic resonance indicated that the biosynthesis of the red pigments used both the polyketide pathway, to generate the chromophore structure, and the fatty acid synthesis pathway, to produce a medium-chain fatty acid (octanoic acid) which was then bound to the chromophore by a trans-esterification reaction. Hence, to enhance pigment production, we tried to short-circuit the de novo synthesis of medium-chain fatty acids by adding them to the culture broth. Of fatty acids with carbon chains ranging from 6 to 18 carbon atoms, only octanoic acid showed a 30 to 50% stimulation of red pigment production, by a mechanism which, in contrast to expectation, did not involve its direct trans-esterification on the chromophore backbone. However, the medium- and long-chain fatty acids tested were readily assimilated by the fungus, and in the case of fatty acids ranging from 8 to 12 carbon atoms, 30 to 40% of their initial amount transiently accumulated in the growth medium in the form of the corresponding methylketone 1 carbon unit shorter. Very interestingly, these fatty acids or their corresponding methylketones caused a strong reduction in, or even a complete inhibition of, citrinin production by M. ruber when they were added to the medium. Several data indicated that this effect could be due to the degradation of the newly synthesized citrinin (or an intermediate in the citrinin pathway) by hydrogen peroxide resulting from peroxisome proliferation induced by medium-chain fatty acids or methylketones.

Improvement of red pigment/citrinin production ratio as a function of environmental conditions by monascus ruber

The growth and metabolic behaviour of the filamentous fungus Monascus ruber were studied in submerged cultures under various aeration and agitation conditions. Improving the oxygen supply, by increasing either the air input or the agitation speed, resulted in modified metabolism: the biomass yield, the consumption of the nitrogen source (monosodium glutamate), and the production of secondary metabolites (red pigment and citrinin) all increased. However, the citrinin production increased more than that of the red pigment. In consequence, a low oxygen transfer coefficient was required to improve the red pigment/citrinin production ratio. Copyright 1999 John Wiley & Sons, Inc.

Production and Identification of N-Glucosylrubropunctamine and N-Glucosylmonascorubramine from Monascus ruber and Occurrence of Electron Donor-Acceptor Complexes in These Red Pigments

The filamentous fungus Monascus ruber produces water-soluble red pigments in a submerged culture when grown in a chemically defined medium containing glucose as a carbon source and monosodium glutamate as a nitrogen source. Two new molecules with polyketide structures, N-glucosylrubropunctamine and N-glucosylmonascorubramine, constituting under some conditions 10% of the total extracellular coloring matter when glucose as a carbon source was in excess (20 g/liter), were isolated and structurally characterized by high-pressure liquid chromatography, Dionex methods, (sup1)H and (sup13)C nuclear magnetic resonance spectroscopy, and mass spectrometry. The occurrence of the electron donor-acceptor complex effect was demonstrated by UV spectroscopy, polarography, and thin-layer voltammetry. The use of n-butanol as an extraction solvent stabilized the pigments against the effects of daylight for several months, promoting the stability of this type of complex.