Modification in the sensory profile of coffee through anaerobic fermentation techniques in processing methods

One technique that has been drawing the attention of producers is the induced fermentation of the fruits. In the induced fermentation process, the fermentation speed is increased, but environmental interferences with different microbiota can alter the fermentation process, making it difficult to repeat the results. The objective was to induce anaerobic fermentations in coffee fruits, through different processes, aiming at modifying the sensory profile of the beverage. The experiment was conducted in 2019, with ‘Mundo Novo IAC-379/19’ coffee fruits, which came from full harvest, with 70% of fruits in the parchment stage. On the day of harvest, the coffee was separated into 78 experimental plots, each containing 10 L. The treatments used were: addition extract of Citrus reticulata, Carica papaya, Ananas comosus, Eucalyptus spp. leaf and addition of sugar, at concentration of 10% in aqueous solution (stored in 12 L buckets) and treatment with water only. 24 and 48h fermentation periods were tested, besides two processing methods, natural and with peeled fruits. In addition, the fruits were tested without induced fermentation for natural and peeled coffee. It is concluded that the treatment with fermentation induced for 24 h without the addition of extracts in wet processing yielded coffees of better sensory quality, with a final score of 85.33. The wet processing of coffee fruits without the addition of extracts, immersed in water for 24 h, yielded better sensory quality. The addition of Ananas comosus extracts implies a reduction in the sensory quality of coffee in the induced fermentation process.

Butanol production from lignocellulosic sugars by Clostridium beijerinckii in microbioreactors

Background Butanol (n-butanol) has been gaining attention as a renewable energy carrier and an alternative biofuel with superior properties to the most widely used ethanol. We performed 48 anaerobic fermentations simultaneously with glucose and xylose as representative lignocellulosic sugars by Clostridium beijerinckii NCIMB 8052 in BioLector® microbioreactors to understand the effect of different sugar mixtures on fermentation and to demonstrate the applicability of the micro-cultivation system for high-throughput anaerobic cultivation studies. We then compared the results to those of similar cultures in serum flasks to provide insight into different setups and measurement methods. Results ANOVA results showed that the glucose-to-xylose ratio affects both growth and production due to Carbon Catabolite Repression. The study demonstrated successful use of BioLector® system for the first time for screening several media and sugar compositions under anaerobic conditions by using online monitoring of cell mass and pH in real-time and at unprecedented time-resolution. Fermentation products possibly interfered with dissolved oxygen (DO) measurements, which require a careful interpretation of DO monitoring results. Conclusions The statistical approach to evaluate the microbioreactor setup, and information obtained in this study will support further research in bioreactor and bioprocess design, which are very important aspects of industrial fermentations of lignocellulosic biomass.

Effect of Feeding Different Cultivars of Leucaena leucocephala on Rumen-Based in vitro Anaerobic Fermentations

The leguminous forage shrub, Leucaena leucocephala, is one of the few nutritional options available to significantly improve beef productivity in Northern Australia. A mixed bacterial rumen inoculum for the detoxification of mimosine (present in Leucaena) and its toxic derivatives 3,4 DHP and 2,3 DHP has been produced in an anaerobic fermenter for the last 23 years by the Queensland Department of Agriculture and Fisheries, using the commercial cultivar Cunninghamii. The development and release of a new psyllid-resistant cultivar ‘Redlands’, offers potential for increasing uptake by the beef industry but brings unanswered questions about its impact on the survival of the toxin degrading bacteria Synergistes jonesii and the overall efficacy of the current inoculum. A series of 30-day anaerobic fermentations were undertaken using the same starter cultures used in the production of commercial inoculum but fed daily with one of three Leucaena cultivars: Cunninghamii, Redlands or Wondergraze. Populations of S. jonesii were monitored daily using a quantitative PCR assay and the ability of the fermentation to detoxify mimosine and its derivatives were assayed on days 10, 15, 20, 25 and 30. Feeding the new Redlands cultivar had a negative impact on S. jonesii numbers and the ability to detoxify 3,4 DHP. However, as fermentation time increased, the S. jonesii populations adapted to the Redlands cultivar. A follow-on fermentation using a starter culture obtained from Day 30 of a Redlands fermentation, showed an immediate increase in S. jonesii populations and was able to detoxify mimosine and its toxic derivatives.

Butanol Production from Lignocellulosic Sugars by Clostridium beijerinckii in Microbioreactors

Background: Butanol ( n- butanol) has been gaining attention as a renewable energy carrier and an alternative biofuel with superior properties to the most widely used ethanol. We performed 48 anaerobic fermentations simultaneously with glucose and xylose as representative lignocellulosic sugars by Clostridium beijerinckii NCIMB 8052 in BioLector® microbioreactors to understand the effect of different sugar mixtures on fermentation and to demonstrate the applicability of the micro-cultivation system for high-throughput anaerobic cultivation studies. We then compared the results to those of similar cultures in serum flasks to provide insight into scalability.Results: ANOVA results showed that the glucose to xylose ratio affects both growth and production due to Carbon Catabolite Repression . The study showed that the BioLector® system is well suited for screening several media and sugar compositions under anaerobic conditions.Conclusions: The approach of, and information obtained in this study will support further research in bioreactor and bioprocess design and scale-up that are very important aspects of industrial fermentations of lignocellulosic biomass.