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.

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Button mushroom (Agaricus bisporus) has been recognized as a fair substitute for meat and is the most intensively cultivated mushroom worldwide. The nutritional value of the mushroom is one of the main factors determining its quality. The current study investigated the variation in nutritional composition of button mushroom as affected by substrate type. Three locally composted wastes were used; chic: deep litter chicken manure, ban: banana wastes (leaves and pseudo-stems) and win: winery wastes (grape marc). Each type of compost was mixed separately with horse manure compost (hors) in different ratios (30%, 50%, 70% and 100%) on volume basis. Control substrate consisted of 100% horse manure compost.Results showed that in the mixture hors-win: 30-70 water, fat, Mg, Fe, Cu, Zn, Na and Ca contents were reduced, while ash and K contents were increased. There was a peak of water (90%), proteins (5.2%), Fe (21.9mg/kg), Cu (18.6mg/kg), Zn (10.2mg/kg), Na (74.5mg/kg), K (2mg/kg) and Ca (65.8mg/kg) contents in mushrooms picked from hors-chic: 0-100. Moreover, growing the mushroom on composted banana wastes (hors-ban: 0-100) produced fruits with the lowest protein (2.9%), fat (0.01%), Mg (147.5mg/kg), Na (64.8mg/kg), K (1.4mg/kg) and Ca (55.8mg/kg) contents and the highest ash content (2%). It seemed that the total use of chicken manure compost allowed the production of mushrooms with the closest nutritional composition to those of the traditional compost.

No previous study assessed the combined effect of olive pruning residues (OLPR) and spent coffee grounds (SCG) on P. ostreatus production and nutritional value. The aim of this study was to determine the capacity of P. ostreatus to degrade lignocellulosic nature of combined OLPR and SCG as well as their resultant nutrient composition. A complete randomized design was adopted with five treatments: S1:100%wheat straw (WS) (control), S2:33%WS+33%SCG+33%OLPR,S3:66%WS+17%SCG+17%OLPR,S4:17%WS+66%SCG+17%OLPR, and S5:17%WS+17%SCG+66%OLPR, and ten replicates per treatment. Substrate’s and mushroom’s composition were analyzed on chemical scale, including fatty acids and heavy metals profiles, following international standards. Only S1, S2, and S3 were productive, with comparable biological yield, economical yield, and biological efficiency. Organic matter loss decreased with increasing proportions of OLPR and SCG. Percentage lignin loss was higher in S1 than in S2 and S3 (53.51, 26.25, and 46.15% respectively). Mushrooms of S3 had some enhanced nutritional attributes compared to control: decrease in fat, increase in protein, increase in monounsaturated fatty acids, and lower zinc accumulation. Lead was less accumulated in S2 than S1 mushrooms. Sodium content of mushroom decreased in S2 and S3. The latter substrates yielded mushrooms with lower polyunsaturated fatty acids (PUFA) and higher saturated fatty acids (SFA) contents. All mushrooms had a valuable PUFA/SFA. This study suggests using OLPR and SCG in low proportions as nutritional supplements to the commercial wheat straw.