Dante Marco De Faveri

Autohydrolysis and organosolv process for recovery of hemicelluloses, phenolic compounds and lignin from grape stalks.

A combination of two environment-friend processes for hemicelluloses and lignin recovery from red grape stalks were investigated: an autohydrolysis pretreatment at 180°C for 30 min followed by a non-catalysed ethanol organosolv step at 180°C for 90 min. Hemicelluloses were precipitated by ethanol addition to autohydrolysis liquor, while lignin was tentatively precipitated by acidification of liquors from both the processes. Results suggest that stalks hemicelluloses can be easily hydrolysed requiring a milder treatment to reduce sugar degradation, while the organosolv process did not give a consistent delignification. Autohydrolysis allowed a recovery of 2% (on stalks d.m.) of total phenols in the liquor. Organosolv liquor had a higher concentration of phenols (corresponding to 0.72% of stalks d.m.) which almost completely precipitated with lignin.

Microwave-Assisted Extraction of Phenolic Compounds from Dried Waste Grape Skins

Abstract Microwave-assisted extraction (MAE) was investigated for recovering of total phenolic compounds from dried waste grape skins using a domestic microwave oven. Influence of vessel geometry, irradiation cycles, irradiation power and time was investigated. The results in terms of phenolics yield, antioxidant capacity and energy consumption were compared with a reference solid–liquid extraction (SLE) carried out for 2 h at 60°C. Equivalent yield of total phenolics as in SLE was achieved with a MAE extraction time of 1,033 sec (corresponding to 83 sec of irradiation at 900 W, 83% saving in extraction time compared to SLE and with a 70% energetic efficiency). Pre-maceration of samples and solvent pre-heating are proposed for large-scale industrial processes to enhance phenolics extraction and process efficiency.

Odor-active Compound Adsorption onto Bentonite in a Model White Wine Solution

This work extends the concepts proposed in a previous research paper about the interaction between the aroma of two white wines and bentonites. Such previous results led to hypothesized that some odor-active compounds were removed through direct adsorption mechanism on the clays. As a consequence, this paper examined the adsorption isotherms at 17±1°C of three bentonite samples added in three different amounts to a model white wine without the presence of wine macromolecule. The clays were analyzed for the elemental composition, the surface charge density, and the specific surface area (SSA) and differences were analyzed by Tukey’s test. The analysis of variance (ANOVA) was used to demonstrate the significance of the bentonite on the aroma reduction. The Langmuir and the Freundlich models were fitted to the adsorption data. The most experimental adsorption isotherms were robustly fitted by the Freundlich equation indicating that, under the condition of the study, the adsorption process more frequently occurred with a heterogeneous energy distribution of an infinite number of surface active sites. Overall, the modeling prediction ability tested by the error on r 2 in cross validation enhanced differences both among the odor-active compounds and among the clays. Samples having a lower SSA value and a greater charge density per surface unit seemed to interact with most of the odor-active compounds primarily through physical mechanisms. Differently, the clay with a large SSA value and a low charge density per surface unit promoted stronger adsorptions that were probably driven by chemical interactions especially for ethyl esters. For the tested odor-active compounds differences in the adsorption intensity and capacity depended mainly on the bentonite characteristics rather than on the properties of the substances.

Improved processing methods to reduce the total cyanide content of cassava roots from Burundi

The identification of highly effective procedures that reduce the cyanogens contained in cassava roots which require no sophisticated equipment, and can readily be adopted by subsistence farmers is of tremendous importance. This study, which used cassava root samples collected in Burundi, included fermentation tests using both selected and native cultures at different temperatures for variable times. Moreover, drying procedures with and without fermentation were carried out. A factorial analysis of variance (ANOVA) showed that the detoxification was mainly affected by fermentation length and by the initial cyanogens content of the roots. When fermentation lasted 48 h and the initial cyanide level was lower than 300 mg/kg dry weight (d.w.), the detoxification was also found to vary based on the microorganism inoculated; Saccharomyces cerevisiae demonstrated the greatest effectiveness. In terms of drying conditions, a temperature of 60°C, even for a shorter duration of time (8 h), lowered the initial cyanide level by more than 90%. Finally, when dehydration followed fermentation, the pressed pulp showed a substantial reduction in cyanide content. By means of this last procedure, safe cassava was produced according to FAO/WHO amendments (10 mg HCN equivalent per kilogram flour), if the initial cyanide level of roots did not exceed 200 mg/kg d.w. Actually, the initial maximum total cyanide content was confirmed to be fundamental in order to obtain safe products in relation to processing method adopted. Keywords : Cassava, cyanide, detoxification, drying, fermentation. African Journal of Biotechnology Vol. 12(19), pp. 2685-2691

Vinegar Production from Pineapple Wastes –preliminary Saccharification Trials

This study is located in the within of a research devoted at processing wastes both in developing and in developed Countries, so reducing both environmental pollution and seasonal fruit losses. In particular, the full work intended to completely process pineapple wastes into vinegar which may be then used as dressing, food preservative, and disinfectant. The preliminary trials presented here deepened the first process step (i.e. the saccharification) and looked into the feasibility of producing the greatest yield of reducing sugars from peels and core of pineapples. Wastes were cut into thin strips, chopped in a mixer, and divided into samples of peel and core to which distilled water was added. For enhancing reducing sugar yield, physical treatments were arranged to disaggregate the fibrous structure followed by enzyme treatments to breakdown cellulose polymers and to hydrolyse sucrose. The optimal time-temperature conditions of each process step were searched for gaining the highest reducing sugars yield at the end of the saccharification. Cellulolytic enzymes were tested for 4-8-18-24 h at 30-40-50 °C, invertase addition was arranged, and amylolytic enzymes were evaluated. All determinations were done in duplicate and a factorial ANOVA with Tukey’s test at p ≤ 0.05 was used to measure the significance of the differences among treatments. The conditions allowing the greatest reducing sugar yield were: the addition to 100 g of waste fresh weight (fw) of 0.025 mL of thermostable α-amylase before a 10 min treatment at 143.27 kPa followed by 24 h-50 °C incubation with 0.05 g pectinase/kgfw, 6 g cellulase/kgfw, 1 g hemicellulase/kgfw, and 0.05 % glucoamylase and pullulanase (Venzyme/kgfw). Then, samples were incubated with 0.05 g invertase/kgfw for 3 h at 50 °C. Under these conditions, more than 100 g of reducing sugars per kg of fresh peels and about 330 g of reducing sugars per kg of fresh core were obtained.

Metabolite profiling and volatiles of pineapple wine and vinegar obtained from pineapple waste

Vinegar is an inexpensive commodity, and economic considerations require that a relatively low-cost raw material be used for its production. An investigation into the use of a new, alternative substrate - pineapple waste - is described. This approach enables the utilization of the pineapples (Ananas comosus) peels and core, which are usually discarded during the processing or consumption of the fruit. Using physical and enzymatic treatments, the waste was saccharified, and the resulting substrate was fermented with Saccharomyces cerevisiae for 7-10days under aerobic conditions at 25°C. This resulted in an alcohol yield of approximately 7%. The alcoholic medium was then used as a seed broth for acetic fermentation using Acetobacter aceti as the inoculum for approximately 30days at 32°C to obtain 5% acetic acid. Samples were analyzed at the beginning and end of the acetification cycle to assess the volatile and fixed compounds by GC-MS and UHPLC-QTOF-MS. The metabolomic analysis indicated that l-lysine, mellein, and gallic acid were significantly more concentrated in the pineapple vinegar than in the original wine. Higher alcohols, aldehydes, and ketones characterized the aroma of the final pineapple vinegar, whilst off-flavors were significantly reduced relative to the initial wine. This study is the first to highlight the metabolite profile of fruit vinegar with a slight floral aroma profile derived from pineapple waste. The potential to efficiently reduce the post-harvest losses of pineapple fruits by re-using them for products with added food values is also demonstrated.

Effect of Bentonite Characteristics on Wine Proteins, Polyphenols, and Metals under Conditions of Different pH

Studies have yet to evaluate how bentonite properties may affect the protein profile, polyphenol content, metal concentration, and heat stability of a white wine at different pH values. Therefore, this work assessed the proteins, polyphenols, metals, and haze forming tendency when heating white wine samples before and after a fining treatment with four activated sodium bentonites in a typical wine pH range (3.00 to 3.60). Soluble wine proteins were separated by sodium dodecyl sulfate - polyacrylamide gel electrophoresis, and gel images were compared using the Quantity One software package (Bio-Rad Laboratories, Inc., Hercules, CA). The wine haze forming tendency, metals, and polyphenols were measured using heat tests and International Organisation of Vine and Wine (OIV) methods. Low molecular mass proteins were efficiently removed by all of the bentonites, regardless of the pH. High and medium molecular mass proteins were less likely to be removed and the efficiency, which depended on the pH, was variable. Reductions of vacuolar invertase (GIN1) and VVTL1 fractions of the thaumatin-like proteins were induced by bentonites with pH values less than 10. These bentonites were affected to a lesser extent by the negative effect of acidic pH. The reduction in haze forming tendency of the unfined Erbaluce wine was particularly noticeable in bentonite fined samples heated at 50 to 60°C, 60 to 80°C, and 70 to 80°C at pH 3.17, pH 3.30, and pH 3.60, respectively. The poor removal of glycoproteins (YGP1 and Hmp1) at higher pH values contributed to an increased thermal stability. The exchange of cationic species, notably sodium and potassium, between the bentonites and the wine was related more to the wine pH than to the clay type. Finally, the extent of polyphenol removal correlated with the amount of protein removed. When protein removal did not occur, the reduction of polyphenols was driven by the specific surface area and the surface charge density of the bentonite.

Fractionation of a Red Grape Marc Extract by Colloidal Gas Aphrons

The objective of the current study was to investigate the application of colloidal gas aphrons (CGA) as a potential low-cost technology for the fractionation of phenolic extracts obtained from off-skins fermented red grape skins with high sugar content. The trials were aimed to investigate the possibility of using CGA generated from the non-ionic surfactant Tween20 to separate phenolic compounds from non-phenolic compounds (minerals and sugars) and to fractionate different fractions of phenolic compounds (total phenols, cinnamic acids and anthocyanins). Separation tests were carried out in a 0.7 L flotation column investigating the effect of both the volumetric ratio CGA/extract sample and the molar ratio CGA/extract sample on both the recovery yields and the separation factor (the ratio between the concentration of a compound in the recovered aphron phase and in the discharged liquid phase). Results revealed the possibility of reaching high recovery yield even though with a poor selective fractionation of the different compounds present in the extract, with glucose and cinnamic acids showing the highest affinity for the aphron phase.

Innovations in the Use of Bentonite in Oenology: Interactions with Grape and Wine Proteins, Colloids, Polyphenols and Aroma Compounds

Bentonite is used in oenology to improve the limpidity and the stability of wine and to predict the formation of deposits in the bottle. The exchangeable cations in its lamellar structures strongly influence some properties, such as the specific surface, the exchange capacity and the adsorption behavior. The unintended use of bentonite for juice settling and/or for wine fining produces jeopardized effects on colloidal and protein stability, the aroma compounds and sensory profiles. The interactions with haze-forming proteins, other colloids, as well as aroma compounds and phenols would have been to discover as the modulation of wine colloids by an adjuvant severely affects the wine resilience and the sensory profile. This chapter reviews several studies that focus on the impact of commercial bentonite samples used for both juice clarification and wine fining on the colloids, proteins, phenols and aroma compounds of white and red wines. Some parameters of practical value, such as the wine heat stability, the concentrations of total and haze-forming proteins and the content of the most relevant aromas, have been assessed to track the effects of bentonite and to achieve findings that are applicable to the field of oenology.

Process development for maltodextrins and glucose syrup from cassava

The objective of this study was to produce maltodextrins (MD) and glucose syrup (GS) throughout a smallscale process from the direct conversion of cassava roots collected in Burundi and previously detoxified. The detoxified cassava slices were blended with water at ratios of 1:1.0; 1:1.3; 1:1.6. Then, the cassava mash was undergone previously to gelatinization and then to liquefaction experiments aimed at obtaining MD with a Dextrose Equivalent (DE) value < 20. The doses of 0.013, 0.016, 0.019, 0.025, and 0.075 % (venzyme/wfresh mash) thermostable α-amylase (Liquezyme-X) were investigated to be added to cassava mash at pH 6.5 before and after 10 min - 90 °C step at atmospheric pressure (patm) or 143.27 kPa (110 °C) allowing the starch gelatinization. Then liquefaction times of 10, 15, 20, 30, 40, 45, 60, 90 and 120 min were tested. The saccharification step followed the liquefaction in order to obtain a GS with DE close to 99. The hydrolyzed cassava mash from liquefaction experiments was added at pH 5.4 and 60°C with 0.019 % (venzyme/wfresh mash) glucoamylase (Dextrozyme GA) and pullulanase (Dextrozyme GX) testing 1, 2, 4, 6, 18, 24, and 48 h incubation times. All experiments were done in duplicate and analysis of variance (ANOVA) with Tukey’s test at p≤0.05 was used to measure the effect of changing variables among treatments. Correlation Pearson’s test were applied to measure the strength of the interactions between the variables. Results showed that the 10 min-143.27 kPa (on lab-scale) and the 12 min-145÷152 kPa (on small-scale) burst of starch granules in 1:1.6 cassava: water mash with 0.013 % (venzyme/wfresh mash) thermostable αamylase at pH 6.5 followed by 15 min-90 °C liquefaction phase at patm allowed at obtaining MD with DE value < 20. In order to gain a GS having a DE value close to 99, a 4 h-60 °C saccharification phase at pH 5.4 with 0.019 % (venzyme/wfresh mash) glucoamylase and pullulanase should be carried out. Finally, highly significant correlations were found out between the water amount in the cassava mash, the concentration of the α-amylase enzyme, and the liquefaction time. This type of process had the advantage to be simple and practical, with reduced working times and enzyme doses, so to be popularizing especially in developing Countries. Further investigations are needed on some energy intensive operations, as like as pH adjustment, pressure increasing, and heating.