Amino acid, mineral, condensed tannin, and other chemical contents of olive leaves (Olea europaea L.) processed via solid-state fermentation using selected Aspergillus niger strains

Abstract

Altop, I. Coskun, G. Filik, A. Kucukgul, Y.G. Bekiroglu, H. Cayan, E. Gungor, A. Sahin and G. Erener. 2018. Amino acids, minerals, condensed tannin, and other chemical contents in olive leaves (Olea europaea L.) processed via solid-state fermentation using selected Aspergillus niger strains. Cien. Inv. Agr. 45(3): 220-230.The present study aimed to examine the effects of solid-state fermentation (SSF) using selective A. niger strains on the amino acid, mineral, condensed tannin, and other chemical contents of olive leaves. The dried samples were divided into nonfermented (C) and fermented (F) olive leaves, and the latter were fermented by the following A. niger strains: ATCC ® 9142 TM (F1), ATCC ® 200345 TM (F2), ATCC ® 52172 TM (F3), and ATCC ® 201572 TM (F4), with three replicates for each treatment. Group F4 presented the best results, although all fermented groups generally presented higher performance than C. The total content of amino acids of the fermented olive leaves increased by 68-209% in comparison to that of C, while the cellulose content of the fermented olive leaves decreased by 7-25%. The ash, crude protein (CP), and ether extract (EE) contents increased after fermentation, but the crude fiber (CF) and nitrogen-free extract (NFE) contents decreased. The content of neutral detergent fiber (NDF) did not change, but acid detergent fiber (ADF) varied among the groups. The starch and sugar contents of all fermented groups except F1 also decreased compared to those of C. The mineral contents increased in all fermented groups, and the condensed tannin content varied according to the A. niger strain used. Thus, olive leaves fermented with different A. niger strains, especially F4, seem to have considerable potential as ruminant feed, as they are enriched with amino acids and minerals and have an improved chemical composition. However, these results should be supported and validated by animal experiments.

Nutritional Enrichment of Apple Pomace by Fungal Fermentations

“…In this study, the crude ash content was increased, however, the reason for the increase is not known precisely because no mineral substance analysis was performed. As a result of fermentation of industrial by-products with bacteria, yeast and fungi, it has been determined that the content of crude fat increases by 20-50% (Joshi and Devender, 2006;Madrera et al, 2017;Altop et al, 2018). Similar results were obtained from previous studies of P. ostreatus fermentation.…”

“…There are many studies reporting decreased crude fibre and its fractions by the solid-state fermentation (Lateef et al, 2008;Yasar and Tosun, 2018c;Karakurt et al, 2019). Altop et al (2018) reported that the starch and sugar content of industrial by-products were reduced as a result of fungal fermentation. In our study, P. ostreatus and P. chrysosporium microorganism fermentation significantly decreased crude fibre, ADF, NDF and reducing sugar, similar to previous studies.…”

Effect of Raw and Fermented Grape Pomace on the Growth Performance, Antioxidant Status, Intestinal Morphology, and Selected Bacterial Species in Broiler Chicks

“…Solid-state fermentation increases radical scavenging activity by raising the amount and/or effectiveness of phenolic compounds in the fermentation medium [ 34 ]. However, A. niger can use some phenolic compounds as a carbon source during fermentation [ 35 ]. A reduction in the radical scavenging activity of GP can be due to A. niger consuming phenolic compounds.…”

Effect of dietary raw and fermented sour cherry kernel (Prunus cerasus L.) on growth performance, carcass traits, and meat quality in broiler chickens

“…In recent years, solid-state fermentation has been an effective tool for recycling agro-industrial residues in useful animal feeds. Solid-state fermentation has improved the nutritional composition of shea nut (Dei et al, 2008 ), cottonseed meal (Jazi et al, 2017 ), pine needle (Wu et al, 2015 ), olive leaves (Altop et al, 2018 ), and sweet cherry ( Prunus avium L.) kernel (Altop, 2019 ). Aspergillus niger can produce various enzymes, such as protease, amylase, lipase, cellulase, and tannase (Couri et al, 2000 ; Wu et al, 2015 ), and also decrease antinutritional components in Ginkgo biloba leaves (Zhang et al, 2012 ), cottonseed meal (Jazi et al, 2017 ), and olive leaves (Xie et al, 2016 ) with solid-state fermentation.…”