Bio-Detoxification of Jatropha Seed Cake and Its Use in Animal Feed

Abstract

Biodiesel production using the seed oil of Jatropha curcas L. (physic nut), as a raw material, results in large amounts of solid residue, called Jatropha seed cake. This seed cake contains lignocellulosic compounds, water, minerals and proteins [1-3]. However, it also contains toxic compounds and anti-nutritional factors [1-3]. The detoxification and reuse of this seed cake is very important for adding economic value, and also reduces potential environmental damage caused by improper disposal of this by-product. The toxicity of Jatropha seed is mainly attributed to a group of diterpene esters called phorbolesters. These esters are present in high concentrations in toxic seed varieties but in lower concentrations in a non-toxic seed variety from Mexico [4]. Phorbol esters activate protein kinase C, a key signal transduction enzyme released in response to various hormones and developmental processes in most cells and tissues [5,6]. In addition to the phorbol esters, there is also a toxic protein called curcin in Jatropha seed cake. This protein has two polypeptide chains and is able to inhibit protein synthesis [7]. Curcin is a ribosome-inactivating protein and promotes mucosal irritation and gastrointestinal hemagglutinating action [8]. Phytic acid (myo-inositol hexaphosphoric acid) and tannins are considered anti-nutritional factors because they inhibit the absorption of proteins and minerals [9-11]. Phytic acid is a compound formed during seed maturation [12]. The seed of J. curcas has a high concentration of phytic acid, up to 10% of its dry matter [2]. Tannins are polyphenols water-soluble and polar solvents [13]. The tannin content in the seeds of J. curcas is low, representing only 3% of its dry weight [13]. Detoxification of the Jatropha seed cake could allow its use as a protein-rich dietary supplement in the animal feed [1,14,15]. The use of residue or by-products in animal nutrition can minimize expenditures on the development of food sources, such as soybean, cotton and wheat meals, without causing undesirable effects on the overall production system. However, it is first necessary to know the nutritional value and effects of the by-product’s inclusion in animal diets. Some studies have used physical and chemical treatments to detoxify Jatropha seed [2,16,17]. These methods have been effective but require the use of chemicals that may result in other the presence of other residues. Conversely, bio-detoxification does not require the application of any chemical compounds. It may also reduce the concentrations of phorbol esters and anti-nutritional factors to non-toxic levels [18].