Maria Daria Fumi

Optimisation of long-term activated-sludge treatment of winery wastewater

Abstract The results obtained in work carried out in order to verify the overall efficiency of full-scale, long-term, activated-sludge treatment of winery wastewater are presented. The analytical data showed the high removal of COD (average 98%; min. 97.6; max. 99.1) during the whole experimentation period and with various working parameters. The effluent had chemico-physical values in conformity with Table A of Italian Law No. 319 of 10 May 1976. Sludge production was lower than that produced by ordinary activated-sludge plants. Moreover, because of the low contents of heavy metals, organic matter and N, P, K content, this aerobic sludge is suitable for direct agricultural use or for compost production. The plant proved itself to be flexible enough to withstand large variations in the hydraulic and pollution loads and was found to have a low running cost.

Transformation ability of fungi isolated from cork and grape to produce 2,4,6-trichloroanisole from 2,4,6-trichlorophenol

The ability of eight fungal strains to transform 2,4,6-trichlorophenol (TCP) to 2,4,6-trichloroanisole (TCA) was studied. These fungi were isolated from cork, belonging to the genera Penicillium, Aspergillus, Trichoderma and Chrysonilia, and from grapes Botrytis cinerea. All, except Chrysonilia, produced TCA when grown directly on cork in the presence of TCP, Aspergillus and Botrytis cinerea being the ones with the highest level of production. It is the first time that Botrytis cinerea, a microorganism often present on grapes and in winery environments, has been shown to transform TCP into TCA. This result can partially explain the wine cork taint before being bottled.

Consumer interest in specialty beers in three European markets

This study explores the quality perception of specialty beers (SBs) in Italy, Spain and Poland. Five-hundred and fifty mainstream beer consumers were enrolled in this study (two-hundred and thirty Italians, one hundred and sixty Poles and Spaniards respectively). The authors adopted a conjoint rating experiment in which the respondents were given forty SB profiles to evaluate. Each profile was described on six attributes (malt type, adjuncts, alternative source of sugars, characterizing ingredients, sensory characteristics, and retail price) varied at different levels and were asked to state his/her preference for each profile on a 9-point scale of interest. The results of this study showed that the ideal SB: (1) for the aggregate Polish panel is brewed from malted wheat, raw wheat, honey, and tropical fruits, is alcoholic and is priced below 2.00 Euros; (2) for the aggregate Italian panel consists of a beer brewed from malted wheat, maize, honey, and vanilla, is blonde and costs a maximum of 2.00 Euros; (3) for the aggregate Spanish panel is brewed from malted wheat, rye or maize, vanilla, is fruity and is priced below 2.00 Euros. The heterogeneity of interest in specialty beers observed in the three countries under test requires for the adaptation of a SB specifically to each culture in which it is sold. In this process of customization, brewers must take into account that gender modulates the effect of culture on consumer interest in SB sensory characteristics and ingredient formulation.

Living immobilized Acetobacter in Ca-alginate in vinegar production: Preliminary study on optimum conditions for immobilization

SummaryThe optimum conditions forAcetobacter immobilization were investigated. The results show that: 1) the maximum oxygen uptake rate (OURm) and cell release are related to alginate and cell concentration in the gel; 2)different alginate concentration does not affect cell viability, but long storage in CaCl2 reduces the number of living cells; 3)the double alginate gel layers had no influence on cell viability and on the OURm and prevented cell leakage from the gel matrix.

Volatile compounds produced by microorganisms isolated from cork

Microorganisms present on cork (i.e. the reproduction bark of Quercus suber L.) can produce odorous compounds affecting the quality of cork stoppers. This work aims to contribute to the study of the correlation between microbial growth and formation of volatile compounds in the cork. Different strains of microorganisms were cultivated on both malt extract and cork, and the odour of the culture was described by a panel. The volatile compounds were isolated directly from the culture media by a dynamic headspace technique followed by adsorption on to Tenax traps. The volatiles were identified by GC–MS: 63 substances were identified in malt extract cultures, mainly consisting of carbonyl compounds (16), alcohols (16), and sesquiterpenes (13). Cultures on cork produced only 12 volatile compounds, more than half being sesquiterpenes. Sensory evaluation confirmed that cork is an unfavourable culture medium if compared with malt extract.

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

Bulk sparkling wine production by external encapsulated yeast bioreactor

SummaryA new method for bulk sparkling wine production is proposed. The use of an external bioreactor with high immobilized yeast loading for second fermentation was studied. The new process is much faster than the traditional one and the sparkling wines obtained are perfectly clear without showing quality faults.

Model for prediction of immobilized Acetobacter cell number in calcium alginate gel droplets

The geometry of calcium alginate gel spheres is studied by fractal interpretation for prediction of number of cells to be immobilized. For alginate concentrations from 1 to 5% the simulated results are of 6.65×108, 1.44×108 and 5.27×107 N cell mL−1 for respectively 1.5, 2.5 and 3.5 mm gel sphere diameters. Simulated data are compared with those resulting from literature and particularly with experimental trials where from 107 to 108 N cell mL−1, in 2% alginate beads with a diameter of 1.5 mm, is able to fulfil mechanical and swelling characteristics of alginate gel beads besides to supply good oxygenation.

Mild Process for Dehydrated Food-grade Crude Papain Powder from Papaya Fresh Pulp: Lab-scale and Pilot Plant Experiments

Proteases are protein digesting biocatalysts long time used in the food industry. Although many authors reported the crystallization of papain and chymopapain from papaya latex, the powder of crude papain had the largest application as food supplements due to its highly positive effect on the degradation of casein and whey proteins from cows milk in the stomach of infants. As the industrial preparative procedures have not been extensively applied, this study aims at producing dehydrated crude papain from fresh papaya pulp, planning lab-scale trials, followed by process development toward the pilot industrial-scale. In the lab-scale experiments, the enzyme activity (EA), expressed as protease unit (PU) /g, were evaluated on pulp and papain standard before and after a 2 h thermal treatment at 70 °C, 90 °C, and 120 °C, and the thermal behavior was monitored by means of differential scanning calorimeter (DSC). The process development toward the pilot-scaling optimized: the homogenization of the fresh pulp, followed by its filtration at high pressure (HP) in order to obtain the vegetation water and the pre-dehydrated pulp which was then oven dried varying the time-temperature conditions (4 h-80 °C; 2 h-120 °C; 30 min-150 °C). Proceeding at higher temperatures for a shorter time allowed obtaining commodity-related and technologically valid products. In the final pilot-scale step, filtration was done with vertical HP filter press, and final dehydration was performed with 2-step turbo-drying: the first aimed to concentrate with 2 min air flow (500 m 3 /h) at 200 °C, the second aimed to dry with 10 min air flow (500 m 3 /h) at 120 °C. The resulting dehydrated pulp was grinded with ball-mill to obtain a stable powder. Starting from 90±2 % pulp moisture, the two turbo-drying steps lowered the water content from 75±4 % to 50±2 % and from 50±2 % to 8±1 %, respectively. The enzyme release from the final powder highlighted an EA of the food-grade crude papain powder extract of 28 PU/g. The thermal steps provided with turbo-driers permitted to maintain a fraction of sugars and pectin acting as a protective structure, so increasing the digestion effects provided by papain. Vegetation waters were ultra-filtered allowing at obtaining a concentrated pectin suspension and rich in nutrient waters which can be reused along the food chain. Further efforts should be made to implement this procedure as potential alternative for the dehydrated crude papain production, deepening the impact of process variables on this matter.

Harmonisation of physical and chemical methods for soil management in Cork Oak forests - Lessons from collaborative investigations

As part of a collaborative project to investigate human impacts on Quercus suber L. (cork oak) forests, five research groups from countries in Europe and North Africa undertook a survey of soil quality (physical properties, potentially toxic elements) at sites in NW Tunisia and NW Sardinia. All groups performed the analysis of soil samples after agreeing prescribed methodologies to ensure harmonisation and the production of a robust and reliable data set. The data produced were compared using basic statistical methods and revealed strong positive correlation despite minor operational variation. The data indicates that inter and intra laboratory variability differed from parameter to parameter and that good agreement was obtained where methodology was common. Collaborative research introduced the need for common communication plans and exchange of information not normally supplied in analytical reporting. Key words: Forest soil quality, inter-comparison, Quercus suber L., cork oak, Tunisia, Sardinia, chemical analysis, potentially toxic elements.