The Effects of Solid State Fermentation on Nutrient Composition of Olive Cake

Project no. 21929 · Status: Kapanmış · 2020

Summary

During the production of olive oil, a high amount of olive cake is obtained as a residual. Although olive cake (OC) is an inexpensive feed raw material that can be used in animal nutrition, its biggest disadvantages are low crude protein content, high cellulose content, and containing anti-nutritional factors. This study, it was aimed to increase the nutritional value of OC by solid state fermentation method with Aspergillus niger and Bacillus subtilis under in vitro conditions.Microorganisms used in the study were incubated for 14 days at 24ºC using potato dextrose agar (PDA). After incubation, spores of microorganisms were applied to ZK as suspension and incubated for 24, 48 and 72 hours. Two trials were carried out in this thesis. In the first trial, the samples were divided into 7 groups with 5 replications as the control group (incubation without microorganisms, K1) and treatment groups (A1-24, A1-48, A1-72, B1-24, B1-48, and B1-72). Then, 100 ml of distilled water was added to 200 g of OC for each replication. In the second trial, similar to the first trial, control (incubation without microorganisms, K2) and treatment groups (A2-24, A2-48, A2-72, B2-24, B2-48, and B2-72) were formed. For each replication, 160 g olive cake + 40 g wheat bran and 100 ml distilled water were added. In both trials, nylon bags were used for fermentation and olive pulps samples were incubated at 30 ºC for 24, 48, and 72 h and then dried with an air oven.Dry matter (DM), crude ash (CA), ether extract (EE), crude protein (CP), sugar, starch, crude fiber (CF), cell wall contents (NDF, ADF, and ADL), total phenolic content (TPC), total flavonoids (TF) and antioxidant activity (AA) analyzes of olive cake were determined before and after fermentation.At the end of the study, it was determined that DM and nitrogen free extract content of fermented OC increased, while the sugar, metabolic energy, EE, TPC, TF, and AA contents were significantly decreased in both trials and in all fermented groups (P<0.05). Except in the fermented groups with A. niger in the first trial, CP content increased in all groups compared to the control (P<0.05). The CF content of the fermented groups with A. niger and B. subtilis decreased in the second trial, but only the fermented groups with A. niger significantly decreased in the first trial (P<0.05). However, only the fermented groups with B. subtilis in the second trial showed a significant decrease in NDF content. The ADF content of all fermented groups was significantly decreased in both trials with A. niger and only in the second trial with B. subtilis (P<0.05). Also, it showed a significant decrease in ADL content only in the first trial with A. niger (P<0.05).As a result, it has been observed that OC as a waste and cheap by-product, could be acquired a potential value of feed and/or feed additive in animal nutrition, especially in poultry nutrition, by solid state fermentation. However, these results need to be confirmed in vivo.

View details