Valorization of Olive Pruning Residues through Bioconversion into Edible Mushroom Pleurotus ostreatus (Jacq. Ex Fr.) P. Kumm. (1871) of Improved Nutritional Value

Abstract

In several Mediterranean countries, olive pruning residues (OLPRs) are abandoned or burned leading to several environmental problems. Valorization of these agrowastes could be a challenge for the primary decomposer Pleurotus ostreatus, turning them into edible biomass. The OLPR was used alone (OLPR), or in mixtures with wheat straw (WS : OLPR 1 : 3 v/v and WS : OLPR 3 : 1 v/v). Mycelial colonization was hastened by 3.7 days in WS : OLPR 1 : 3 (v/v). Yields were comparable to control (WS) in WS : OLPR 3 : 1 (v/v). Organic matter loss decreased with increasing proportions of OLPR in substrates. The nutritional value of mushrooms was improved by lower fat and sodium contents, in WS : OLPR 1 : 3 (v/v) and WS : OLPR 3 : 1 (v/v), and higher total protein, crude fiber, iron, and total carbohydrates contents in WS : OLPR 3 : 1 (v/v), compared with those of control. Polyunsaturated fatty acids, mainly linoleic acid, were the most abundant in mushrooms. Monounsaturated fatty acids increased in mushrooms of the substrates containing OLPR. A good predictive model of partial least square regression analysis showed different relationships of mushroom palmitic, oleic, linolenic, palmitoleic, and stearic acids with substrate composition. Findings suggested the use of OLPR as a supplement to commercial wheat straw and as a tool to reduce the negative impacts of their hazardous disposal on the environment.

Combined effect of olive pruning residues and spent coffee grounds on Pleurotus ostreatus production, composition, and nutritional value

“…Substrates S4 and S5 weren't fully colonized by the mycelium, they only attained a level of 50% mycelial colonization (MC). Early findings showed the possibility of gaining production from mixing high proportions of SCG or OLPR (67%) with low proportion of WS (33%) [17,18]. However, in this study, when both tested wastes (SCG and OLPR) formed together 83% of substrate, the C/N ratio was strongly reduced (26:1 and 37:1 respectively in S4 and S5, compared to 69:1 in WS) (Table 1), assumedly causing a negative effect on mycelia run.…”

“…The mushroom capacity to absorb chemical compounds from the used substrate and the correlation between mushroom's and substrate's chemical composition has been demonstrated in a number of early reports [14,[20][21][22][23]. For instance, Abou Fayssal et al [17] and Alsanad et al [18] tested the potential of using abandoned OLPR or SCG on the production and nutritional value of P. ostreatus production, and demonstrated a direct impact of the substrate composition on the mushroom's fatty acids profile. However, the combined use of both types of agro-industrial residues (OLPR and SCG) in P. ostreatus growth substrate is not reported yet.…”

“…Successful implementation of agro-industrial wastes in mushroom production has been delineated in a number of studies [12][13][14][15][16]. Particularly, the study conducted by Abou Fayssal et al [17] succeeded in reducing the dangerous hazard left over of olive pruning residues (OLPR) represented by open-field burning and fire risks. The production of a lower fat and sodium mushrooms with cardiovascular protection properties was also demonstrated.…”

Nano urea effects on Pleurotus ostreatus nutritional value depending on the dose and timing of application

“…Mushrooms grow on agricultural wastes by secreting enzymes to digest the surrounding foodstuffs and get their nutrients from the substrate 44 . Therefore, their nutritional composition will largely depend on the chemical composition of the growing substrate [7][8][9][10][11][12] . In early studies, the changes in mushroom nutritional composition were mostly addressed when various nutrient additives were applied at spawning.…”

Production and composition of Pleurotus ostreatus cultivated on Lithovit®-Amino25 supplemented spent substrate

“…The mushroom nutrient composition is affected by the substrate composition and properties (El Sebaaly et al 2018 , 2019 ; Abou Fayssal et al 2020 ). The mushroom nutritional value may be improved as by applying nano-amino at spawning; proteins increase with the highest dose used, and essential amino acids with the lowest one.…”