RESEARCH PROJECT

Fermentation of agricultural by-products and slaughterhouse waste to replace soybeans

Research team
The team is made up of members of the research groups of the Autonomous University of Barcelona (UAB, for its initials in Catalan):

• Applied and Environmental Microbiology Group of the Animal Anatomy Department. Prof. Responsible Dr. M. Àngels Calvo.
• Ruminant Research Group of the Department of Animal and Food Science. Prof. Responsible Dr. Gerardo Ceja.
• Organic Solid Waste Composting Group of the Chemical Engineering Department. Prof. Responsible Dr. M. Teresa Gea.

REPORT
Background
The treatment of industrial waste poses an important environmental problem due to its volume, and its physical-chemical characteristics. In recent years, a large number of research projects and publications have been carried out, which propose adding value to different types of by-products (Balandran-Quintana et al., 2015, Jahurul et al., 2015, Palumbo et. al., 2015). It must be borne in mind that many of the industrial waste and by-products contain carbohydrates (sugars and fiber) and / or proteins, which can be used as substrates, either directly or after biological transformations, to obtain high-value compounds for animal feeding (Bellaver et al., 2005, Molina-Alcaide et al., 2008, Molina-Alcaide and Yánez-Ruiz, 2008, Soto et al., 2015).

From the study carried out the previous year, different types of more suitable by-products could be selected to carry out the research that is being considered and preliminary studies have also been done for the selection of groups of microorganisms of interest in achieving the desired transformations.

The final composition of the products obtained depends on the type of substrate and inocula used, as well as to the conditions of the fermentation process, which has been the subject of very few studies in the case of agricultural and agri-food waste.

From the first studies carried out we propose to work on fruit residues, dairy industry residues, molasses and also on contaminated algae of river channels and that make it difficult to manage the water of these rivers properly and their subsequent elimination when they are removed of the course of the waters.

OBJECTIVES
The main objectives of the project are:

• To study the fermentative characteristics and optimization factors of the fermentation process, including innovative microbial inoculants, for their profitability and the quality of the obtained products.
• To study the composition and nutritional assessment of the products obtained for use as protein supplements for animal feed.

RESEARCH PLAN

Activity 1

Fermentation study of the selected materials

In a first phase the fermentation potential of the selected substrates will be determined, on a laboratory scale and at a controlled temperature, in test tubes to make a first selection, and later those that allow obtaining better results will be developed on the selected substrates at different scales: 500 ml flask and finally 1 L reactors equipped with pressure measurement for the calculation of the biogas produced (Ponsà et al., 2011).

Innovative inoculants will use lactic bacteria, yeasts and a mixture consisting of milk bacteria, yeasts and phototrophic bacteria. The improvement of the digestibility of the waste and its nutritional power and, in parallel, the production of biogas, a source of renewable energy, will be evaluated.

The results obtained with the different microorganisms will be compared when developing on substrates, such as:
– Residue of fruits: apples and oranges
– Algae coming from the channels of the Ebro river and that represent a serious source of waste, when they want to eliminate
– Molasses
– Dairy products residues
– Slaughterhouse waste

Microbial strains isolated from different substrates will be used (Ávila et al., 2014). From the fermentation potential and the characteristics of the waste, the selection of the materials will be carried out, including the formulation of possible mixtures.

In the formulation, the quantity and seasonality with which these residues are generated will also will be factor in. Once the optimal substrates have been defined, the fermentation of the best potential substrates in higher volume bioreactors will be evaluated (Maulini-Duran et al., 2015).

The final samples obtained will be kept for analysis to Activity 2.

Activity 2

Study of the composition and nutritional assessment of the products obtained for use as protein supplements in animal feed

The evaluation of the nutritional value of the samples obtained from the previous activity is proposed. The chemical composition of the samples will be determined following the classic schemes of Weende and Van Soest (AOAC, 2003).

NOTES

* You can read the first part of this article in the following link: Production of protein intended for animal feed from microorganisms. Part 1.

* This article has been published in the journal of the Academy of Veterinary Sciences of Catalonia (ACVC, for its initials in Catalan) of the year 2017.