Abstract
PurposeOlive oil industry is a growing industrial sector in Mediterranean countries. Unfortunately, about 30–35% of total olive weight is discarded as olive pomace (OP), a highly environmental-polluting solid waste. OP is mostly used for composting and production of animal feed; nevertheless, the high oil content, phenolic compounds and fiber contents in addition to its low protein content represent major obstacles for both applications. So, the present study was conducted to evaluate the role of solid state fermentation (SSF) in OP using Kluyveromyces marxianus NRRL Y-8281 yeast on the chemical composition and tannin content of OP in a trial for its bioconversion into a value-added animal feed.MethodsChemical composition, nutritive and energetic values, tannin and gallic acid contents of unfermented and fermented olive pomace were investigated.ResultsThe fermentation altered the chemical composition of OP, so that crude fiber was decreased by 8.56%, while crude protein, fat and carbohydrate contents were increased by 2.74, 2.63 and 3.57%, respectively. Moreover, the effect of fermentation on cell wall constituents, gross energy, digestible energy, total digestible nutrients and digestible crude protein was evaluated. Furthermore, HPLC analysis revealed that K. marxianus mediated fermentation of OP resulted in a sharp decrease in tannin content by 96.75% with 2.8 times increase in gallic acid concentration.ConclusionSSF of OP by K. marxianus does not only eliminate the environmental pollution resulting from its accumulation, but also presents a new eco-friendly valorization technique which leaves OP with an altered chemical composition allowing its use as animal feed or compost.
Highlights
IntroductionIt is estimated that the world annual production of olive pomace (OP) is 2,881,500 tonnes/year (Nunes et al 2016)
Olive oil industries play an important economic role in Mediterranean countries
This represents a huge problem for olive oil producing countries, since this vast amount of waste cannot be stored in its original form for extended time due to its high water and significant oil contents that cause rapid deterioration and rancidity often after 4–5 days of its production, as a result, olive pomace (OP) is spread on farm lands resulting in serious negative environmental impact regarding soil, underground water and air problems (Brlek et al 2012)
Summary
It is estimated that the world annual production of OP is 2,881,500 tonnes/year (Nunes et al 2016) This represents a huge problem for olive oil producing countries, since this vast amount of waste cannot be stored in its original form for extended time due to its high water and significant oil contents that cause rapid deterioration and rancidity often after 4–5 days of its production, as a result, OP is spread on farm lands resulting in serious negative environmental impact regarding soil, underground water and air problems (Brlek et al 2012). OP is quite rich in water (30–50%) and contains a substantial amount of residual oil (2–4%) (Azbar et al 2004) It is characterized by high fiber (cellulose, hemicellulose, lignin and pectines) and low protein contents. OP is a ligno-cellulosic organic material which has low digestibility and energy content in addition to having high tannin content (Al-Masri and Guenther 1999)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal of Recycling of Organic Waste in Agriculture
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
