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Biotechnological potential of coffee pulp and coffee husk for bioprocesses

Advances in industrial biotechnology offer potential opportunities for economic utilization of agro-industrial residues such as coffee pulp and coffee husk. Coffee pulp or husk is a fibrous mucilagenous material (sub-product) obtained during the processing of coffee cherries by wet or dry process, respectively. Coffee pulp/husk contains some amount of caffeine and tannins, which makes it toxic in nature, resulting the disposal problem. However, it is rich in organic nature, which makes it an ideal substrate for microbial processes for the production of value-added products. Several solutions and alternative uses of the coffee pulp and husk have been attempted. These include as fertilizers, livestock feed, compost, etc. However, these applications utilize only a fraction of available quantity and are not technically very efficient. Attempts have been made to detoxify it for improved application as feed, and to produce several products such as enzymes, organic acids, flavour and aroma compounds, and mushrooms, etc. from coffee pulp/husk. Solid state fermentation has been mostly employed for bioconversion processes. Factorial design experiments offer useful information for the process optimization. This paper reviews the developments on processes and products developed for the value-addition of coffee pulp/husk through the biotechnological means.

Biological detoxification of coffee husk by filamentous fungi using a solid state fermentation system

Studies were carried out on detoxification of coffee husk in solid state fermentation using three different strains of Rhizopus, Phanerochaete, and Aspergillus sp. Fungal strains were selected by their ability to grow on a coffee husk extract-agar medium. Using R. arrizus LPB-79, the best results on the degradation of caffeine (87%) and tannins (65%) were obtained with pH 6.0 and moisture 60% in 6 days. When P. chrysosporium BK was used, maximum degradation of caffeine and tannins were 70.8 and 45%, respectively, with coffee husk having 65% moisture and pH 5.5 in 14 days. The Aspergillus strain, isolated from the coffee husk, showed best biomass formation on coffee husk extract-agar medium. Optimization assays were conducted using factorial design, and surface response experiments with Aspergillus sp. The best detoxification rates achieved were 92% for caffeine and 65% for tannins. The results showed good prospects of using these fungal strains, in particular Aspergillus sp., for the detoxification of coffee husk.

Development of a bionematicide with Paecilomyces lilacinus to control Meloidogyne incognita

Root-knot disease caused by Meloidogyne incognita is a matter of grave concern because it affects several economically important crop plants. The use of solid-state fermentation (SSF) may help to elaborate efficient formulations with fungi to be employed in the biologic control of nematodes. Attempts were made to select low-cost substrates for spore production of a strain of Paecilomyces lilacinus with known nematicide capacity. Coffee husks, cassava bagasse, and defatted soybean cake were utilized as substrates, and sugarcane bagasse was used as support. Fermentations were carried out in flasks covered with filter paper at 28°C for 10 d. The products obtained by SSF were evaluated for their nematicide activity in pot experiments containing one seedling of the plant Coleus inoculated with the nematode M. incognita. The plants were evaluated 2 mo after inoculation. Fermented products showed a reduction in the number of nematodes. The best results were obtained with defatted soybean cake, which showed almost 100% reduction in the number of nematodes; the reduction with coffee husk was 80% and with cassava bagasse was about 60%.

Spore production of Beauveria bassiana from agro-industrial residues

The purpose of this work was to produce Beauveria bassiana by Solid-State Fermentation using agro-industrial residues and optimizing the cultivation conditions. Refused potatoes, coffee husks and sugar-cane bagasse were tested. The blend of refused potatoes and sugar-cane bagasse (60-40%) with particle size in the range of 0.8-2 mm was used in the fermentation experiments. In Erlenmeyer flasks the best spore production was achieved with the following conditions: incubation temperature 26o C; initial pH 6.0; inoculum concentration 107 spores.g-1.dw and initial moisture 75%. In the column type reactor using forced aeration under the optimized conditions, the maximum production (1.07x1010spores.g-1.dw) was obtained at the 10th day of fermentation. The respirometric analyses of the fermentation showed a strong correlation between fungal growth and spore production.

Conidia Production of Beauveria sp. by Solid-State Fermentation for Biocontrol of Ilex paraguariensis Caterpillars

Conidia production ofBeauveria sp. strain LAG by solid-state fermentation (SSF) using blends of agro-industrial residues (residual potatoes and sugar-cane bagasse) was optimized with respect to cultivation conditions and the composition of substrate mixture in Erlenmeyer flasks and column-type bioreactor. With a blend of 60 % residual potatoes and 40 % sugar-cane bagasse the optimum conditions achieved were: incubation temperature 26 °C, initial substrate pH 6, inoculum concentration 107 conidia per g substrate; optimal initial moisture of the substrate was 70 % for Erlenmeyer flasks, in column-type bioreactor (with forced aeration) the optimal initial moisture of the substrate was 65 % with airflow of 60 mL/min. The highest production (1.07 × 1010 conidia per g dry substrate) was achieved after a 10-d fermentation. The conidia were used in laboratory assays againstThelosia camina andHylesia sp., caterpillars that are serious pests of mate plants. The mortality ofT. camina was >90 % 10 d after spraying caterpillars with 1 mL conidia suspension at a concentration 105–108/mL. ForHylesia sp., the mortality was 70 %, 7 d after immersion in the conidia suspension containing 108 conidia per mL. Therefore, theBeauveria sp. LAG can be considered to be an important biocontrol instrument in the prospect of the Integrated Pest Management for mate plants.

Relationship between coffee husk caffeine degradation and respiration of Aspergillus sp. LPBx in solid-state fermentation

Studies were carried out in a packed-bed column fermentor using coffee husk as substrate in order to verify a relationship between caffeine degradation and the respiration of Aspergillus sp. LPBx. Fermentation conditions were optimized by using factorial design experiments. The kinetic study showed that the caffeine degradation was related to the development of mold and its respiration and also with the consumption of reducing sugars present in coffee husk. From the values obtained experimentally for oxygen uptake rate and CO2 evolved, we determined a biomass yield of 3.811 g of biomass/g of consumed O2 and a maintenance coefficient of 0.0031 g of consumed O2/(g of biomass·h). The maximum caffeine degradation achieved was 90%.

The uptake of different iron salts by the yeast Saccharomyces cerevisiae

Yeasts can be enriched with microelements, including iron; however, special physicochemical conditions are required to formulate a culture media that promotes both yeast growth and iron uptake. Different iron sources do not affect biomass formation; however, considering efficacy, cost, stability, and compatibility with Saccharomyces cerevisiae metabolism, ferrous sulphate is recommended.

Microbial Degradation of Caffeine and Tannins from Coffee Husk

Brazil contributes approximately 25% of the world’s coffee production. During 1998, it’s production reached two million tons coffee beans. Parana State is one of the most important States for coffee cultivation in the country. Its production was 280,000 tons (representing about 14% of total Brazilian production) during 1998. Only 6% of the fresh grain is utilized for the production of the beverage, the remaining 94% is constituted by water and sub-products of the process (Zuluaga, 1989). In Brazil, coffee cherries are generally sun dried and subsequently the outer layers of husk covering the green coffee are removed by a hulling machine as and when needed. This residue poses a serious environmental concern due to its disposal in rivers, lakes located near the coffee processing regions. In view of its richness in proteins, fibres, carbohydrates and minerals, it has been suggested that it could be used as animal feed and organic fertilizer with suitable bio-treatments. It could also be used as substrate for the production of biogas, enzymes edible mushrooms, etc. (Gaime-Perraud, 1996; Fanet al., 1999a, b, c 2000a, b; Pandey and Soccol, 2000).

Morphological and molecular identification of filamentous fungi isolated from cosmetic powders

Seven fungi were isolated from 50 samples of cosmetic powders. Morphological analyses and ribosomal DNA Internal Transcribed Spacers sequencing were performed which allowed the discrimination of the isolated fungi as Aspergillus fumigatus, Penicillium sp., and Cladosporium sp. which could have, among their species, potentially pathogenic microorganisms.