Spent coffee grounds influence on Pleurotus ostreatus production, composition, fatty acid profile, and lignocellulose biodegradation capacity

ABSTRACT

The capacity of Pleurotus ostreatus to degrade the lignocellulose of spent coffee grounds (SCG) and its resultant nutrient composition is not yet studied. The study tested four SCG/wheat straw mixtures, containing 0, 33, 67, or 100% SCG. Initial lignin content was higher, and lignin loss was lower in mixtures containing SCG, compared to control revealing lower substrate degradation. Biological yield was negatively correlated with initial lignin content, and positively with the lignin loss from substrates. The nutritional value of mushrooms was improved by a general increase in carbohydrates, a decrease in sodium content with 33% and 67% SCG, and lower fat content with 33% SCG. Polyunsaturated fatty acids of mushrooms (PUFA) increased with 67% SCG; while saturated ones (SFA) increased with 33 and 67% SCG. All mushrooms had a close PUFA/SFA, ranging between 7.4 and 8.1. The study suggests using SCG as a nutritional supplement to the commercial wheat straw.

Graphical abstract

RESUMEN

Aún no se ha estudiado la capacidad de Pleurotus ostreatus (champiñón ostra, o seta) para degradar la lignocelulosa de los desechos de café molido (SCG) y su consiguiente composición de nutrientes. El presente estudio probó cuatro mezclas de SCG/paja de trigo, que contenían 0, 33, 67 o 100% de SCG. En comparación con el control, que reveló una menor degradación del sustrato, el contenido inicial de lignina fue mayor y en las mezclas que contenían SCG la pérdida de lignina fue menor. El rendimiento biológico se correlacionó negativamente con el contenido inicial de lignina y lo hizo positivamente con la pérdida de lignina de los sustratos. El valor nutritivo de los champiñones mejoró debido a un aumento general de los carbohidratos, una disminución del contenido de sodio, en las mezclas que contenían 33% y 67% de SCG, y un menor contenido de grasa en la mezcla que contenía 33% de SCG. Los ácidos grasos poliinsaturados de los champiñones (PUFA) aumentaron en la mezcla con 67% de SCG; mientras los saturados (SFA) se incrementaron en aquellas con 33% y 67% de SCG. Todos los champiñones tuvieron un índice PUFA/SFA semejante, que oscilaba entre 7.4 y 8.1. En conclusión, este estudio sugiere usar SCG como suplemento nutricional de la paja de trigo comercial.

KEYWORDS:

• Bioconversion
• industrial waste
• mushroom production
• mushroom composition
• fatty acids

PALABRAS CLAVE:

• bioconversión
• residuos industriales
• producción de champiñones
• composición de champiñones
• ácidos grasos

Data availability

Due to the nature of this research as a part of a PhD thesis, participants of this study did not agree for their data to be shared publicly, so supporting data is not available.

Disclosure statement

Authors confirm that there is no conflict of interests from the presented study.

Notes

1. P. ostreatus: Pleurotus ostreatus, SCG: spent coffee grounds, WS: wheat straw, CaCO₃: calcium carbonate, MC: mycelial colonization, PN: time to pinhead initiation, H1: time to first harvest, DAS: days after spawning, BE: biological efficiency, PD: pileus diameter, SL: stipe length, EC: electro-conductivity, OM: organic matter, LARI: Lebanese Agricultural Research Institute, LFDCA: Lebanese Food Drugs and Chemicals Administration, AOAC: Association of Official Analytical Chemists, HPLC: High Performance Liquid Chromatography, GC-MS: Gas Chromatography Mass Spectrometry, NDF: neutral detergent fiber, ADF: acid detergent fiber, ADL: acid detergent lignin, HCL: Hydrochloric acid, KOH: Potassium hydroxide, GC-FID: Gas chromatography with Flame Ionization Detector, K: potassium, Ca: calcium, Mg: Magnesium, Na: Sodium, Fe: iron, Mn: Manganese, ICP-AES: Coupled Plasma-Atomic Emission Spectrophotometry, SPSS: Statistical Package for Social Sciences, PLSR: partial least squares regression, HN: harvests number, BN: bunches number, FBN: fruit body number, BW: bunches weight, FBW: fruit body weight, BY: biological yield, EY: economic yield, SD: stipe diameter, Pro: total protein, CF: crude fiber, Carb: total carbohydrates, TSS: total soluble sugars, FRU: fructose, GLC: glucose, SUC: sucrose, PUFA: polyunsaturated fatty acids, MUFA: monounsaturated fatty acids, SFA: saturated fatty acids, C18:2: linoleic acid, C18:3: linolenic acid, C16:1: palmitoleic acid, C18:1: oleic acid, C20:0: arachidic acid, C16:0: palmitic acid, C18:0: stearic acid, nd: not detected, RMSE: root means square error, M: mushroom, LDL: low-density-lipoprotein.