R.B. Lo Curto

SCP and crude pectinase production by slurry-state fermentation of lemon pulps

Single cell protein (SCP) and crude pectinolytic enzymes production from citrus pulps is reported. SCP and enzymes were produced by slurry-state flask cultivation of Aspergillus niger and Trichoderma viride on pulps from lemon juice clarification. Production as well as crude pectinase activity was not affected by the high dry matter content of the pulps. Both the protein content in the residue and the enzyme activity in the supernatant were higher in T. viride than in A. niger culture. The crude pectinase of T. viride, whose specific activity was similar to that found for a commercial concentrated preparation, could be utilized in the same citrus processing factory as well as in other factories which use large amounts of pectinolytic crude preparations, for example to enhance depuration plant performance.

Synergy between xylanases from glycoside hydrolase family 10 and family 11 and a feruloyl esterase in the release of phenolic acids from cereal arabinoxylan.

The bioconversion of waste residues (by-products) from cereal processing industries requires the cooperation of enzymes able to degrade xylanolytic and cellulosic material. The type A feruloyl esterase from Aspergillus niger, AnFaeA, works synergistically with (1→4)-β-d-xylopyranosidases (xylanases) to release monomeric and dimeric ferulic acid (FA) from cereal cell wall-derived material. The esterase was more effective with a family 11 xylanase from Trichoderma viride in releasing FA and with a family 10 xylanase from Thermoascus aurantiacus in releasing the 5,5′ form of diferulic acid from arabinoxylan (AX) derived from brewers’ spent grain. The converse was found for the release of the phenolic acids from wheat bran-derived AXs. This may be indicative of compositional differences in AXs in cereals.

Ochratoxin A occurrence in experimental wines in relationship with different pesticide treatments on grapes

Abstract A reversed-phase HPLC method was utilized for Ocrhratoxin A (OTA) determination in 23 white and red wine samples produced in the year 2000. All were come from some vineyards, treated with different pesticides, located in three Italian regions. Analytical methods included commercial immunoaffinity columns and a HPLC system equipped with a RF detector. The sensitivity of the analytical method was 0.01 ng ml −1 . Values of OTA found in wine samples show that OTA is more frequently detected in red than in white wines. In fact, all red wine samples were contaminated. The OTA levels reported in this work are comparable with those reported for mycotoxin in red wine. Moreover, the different contents of Ochratoxin A in the wines can be considered an efficiency index of pesticides used.

Flavonoids recovery and SCP production from orange peel

Abstract Further results of research on orange peel utilization are presented. From the solid residue obtained after an acidic pretreatment of the peel, hesperidin, a high-value byproduct, may be recovered in larger quantities and at lower cost than for a traditional method. A continuous fermentation for SCP production, utilizing Geotrichum candidum , was carried out on the pretreatment liquid. These results are discussed.

Lipid composition of Geotrichum candidum single cell protein grown in continuous submerged culture

Abstract Continuous cultivation of Geotricum candidum grown on orange peel extracts produced a high-protein, low-lipid content single cell protein which could be utilized as feed or proteic extract source. The lipid content, ca 4%, was very low compared with the data available in the literature, a result which might be attributed to the fermentation conditions employed in this study. The lipid composition of the dried biomass of this fungus is reported and briefly discussed.

Yeast production from virgin grape marc

An alternative utilization of virgin grape marc (VGM) to produce SCP from S. ceretisiae is reported. A simple extraction method of fresh grape marc produces a sugar-rich solution: through fed-batch fermentation, a high-value yeast biomass instead of a low-value product like ethanol can be produced. Productivity and quality of yeast are similar to these obtainable from molasses. The convenience of yeast production from VGM is briefly discussed; it appears of great interest in south Italy and generally in grape-producing countries, specially if these lack relevant sources of fermentable sugars.

SCP from orange peel by fermentation with fungi—Acid-treated peel

Abstract Orange peel was submitted to an acidic pretreatment. After filtration, a cellulosic residue, suitable as a feedstuff for ruminants, weighing 35–45% of the initial dry matter, was obtained. The fermentation was then carried out on the filtered liquid by utilizing Geotrichum candidum . Single cell protein containing 35–40% crude protein characterized by a very high in vitro digestibility (73–88%) was obtained. Advantages of this system, besides the high quality of the product, are a reduction of the fermentor size in comparison with submerged fermentation and the solution of the problems linked to the disposal of the final liquid. In fact this liquid, because of its reduced volume, may be partially concentrated and added to the residue of the pretreatment.

SCP from orange peel by fermentation with fungi—Submerged and ‘surface’ fermentations

Abstract Orange peel was employed as a fermentation substrate to produce single cell protein (SCP) by utilizing Trichoderma viride and Geotrichum candidum . Submerged fermentations lasted about 60 h and gave rise to a final product, composed of a mixture of SCP and orange peel residue, suitable as feedstuff; this contained about 20% crude protein and 23% crude fibre and had an invitro total digestibility of about 65%. Fermentations in the presence of little water, according to a new system which may be called ‘surface fermentation’, gave rise to a biomass of a higher nutritional value (about 30% crude protein and 80% in-vitro total digestibility), but with a decreasing production efficiency with time.

Effect of SO2, NaOH and Na2CO3 pretreatments on the degradability and cellulase digestibility of grape marc

Abstract As part of research on the utilization of grape marc as a carbon source for single cell protein (SCP) production, virgin grape marc (VM) and exhausted grape marc (EM) were pretreated at high temperature with water, SO2, Na2CO3 and NaOH solutions in various concentrations. The effect of these treatments was determined by measures of dry matter, nitrogen, ADF, lignin and cellulose, as well as of total cellulase digestibility on the residual grape marcs. The drying of original marc, even at 70°C, severely affected the susceptibility to degradation of lignocellulosic materials (LCM). Therefore storage in a damp state is necessary. The addition of Na2CO3 (about 10% on dry matter) served this purpose and also acted as an efficient pretreatment agent. NaOH (1%) solution at 120°C caused the greatest degrading effects, but also a notable solubilization of nitrogen compounds; 1·5% SO2 solution at 100°C had a good effect on VM but not on EM; 0·5% NaOH solution and 1·0% Na2CO3 solution showed intermediate features.

Grape marc as a source of feedstuff after chemical treatments and fermentation with fungi

Abstract The results are presented of research linked to the utilization of grape marc as a substrate for SCP production, after pretreatments with Na2CO3 and NaOH at 120°C, by Aspergillus sp., Geotrichum candidum and Trichoderma viride. Submerged fermentations were slow and gave rise to only a modest increase of crude protein (from 2·2% to about 4% nitrogen on d.m.) and in-vitro digestibility (from 15·0% to about 26·0%). Fermentations carried out on the liquid resulting after NaOH pretreatments gave rise to modest SCP growth, probably because of the inhibitory effects of polyphenols (hydrolyzed by NaOH treatment, but recomposed under the fermentation conditions), and of the lignin degradation products present in the liquid. Experiments suggest that a possible way for a profitable utilization of this waste material is to submit it to consecutive alkaline and acidic treatments, which gives two products, whose value as feedstuffs for ruminants should be confirmed with in-vivo alimentation assays.