Biomass is one of the best sources to meet the energy demands of the future as it is not only renewable but also environmentally friendly. The energy obtained from biomass is used mainly in heat production, electricity, and as fuels for vehicles (Houshfar et al. 2014). Various advanced technologies have been developed to obtain biofuels and/or biochemicals from biomass, which include the hydrothermal process (Jin and Enomoto 2011), pyrolysis (Torri et al. 2009), and combustion (Vassilev et al. 2013).

Pyrolysis of biomass is one of the most efficient technologies used to produce biofuel. The process is carried out at elevated temperatures under an inert atmosphere which is maintained using either argon or nitrogen gases. The process yields bio-oil, solid residue, and gaseous products. Process conditions, as well as the raw materials used, have varying effects on the yields of each product.

Bio-oils and bio-chars are two significant pyrolysis products, and they have their own significant values which can be utilized in a sustainable way. Bio-oils can be used as transportation fuels after they are upgraded using a process such as deoxygenation and dearomatization (Huber et al. 2006; Amen-Chen et al. 2001). Biofuels can be blended with diesel fuels with the assistance of surfactants (Huber et al. 2006; Bridgwater 2004). They can also be evaluated as a source of value-added chemicals after isolation and purification (Amen-Chen et al. 2001).

Bio-chars from pyrolysis of biomass are also perspective products which can be used to improve soil functions (Marousek 2013a). Production and storage of bio-chars in soils have some beneficial aspects such as the mitigation of climate change by sequestering carbon (Marousek et al. 2014a; Marousek 2013b), leading to an increase in the capacity of soil to store water (Marousek 2014), an increase in soil microbial biomass (Marousek 2014), and an increase in yields of crops (Marousek et al. 2014a).

Fruit wastes and their by-products are important biomass resources for the scientific community to evaluate as potential energy sources. Many studies are available in the literature concerning the pyrolysis of fruit wastes for the production of biofuel via pyrolysis, such as sesame, mustard and neem de-oiled cakes (Volli and Singh 2012), tamarind seed (Kader et al. 2013), jatropha oil cakes (Raja et al. 2010; Jourabchi et al. 2014), palm kernel cake (Ngo et al. 2013), cottonseed cake (Putun et al. 2006), and pomegranate seeds (Ucar and Karagoz 2009).

Nayan et al. investigated the production of bio-oil from the pyrolysis of neem seed at the temperature zone from 400 to 500 °C and a heating rate of 20 °C min−1 (Nayan et al. 2013). The greatest bio-oil yield (38 wt%) was accomplished at 475 °C. Hydrocarbons identified in the bio-oils were numerous and varied. Prominent compounds identified in the bio-oils were octadecanenitrile, oleanitrile, 9-octadecenoic acid methyl ester, and stearic acid methyl ester.

Pyrolysis of karanja seed to produce liquid fuel was carried at temperatures ranging between 500 and 600 °C (Shadangi and Mohanty 2014). The optimal temperature used for the production of the greatest bio-oil yield (55.2 wt%) was 550 °C. The bio-oil contained a mixture of oxygenated hydrocarbons including phenols, acids, esters, hexane, levoglucosan, amide, nitrile, benzene, furan, and other compounds.

Shadangi and Singh explored the pyrolysis of polanga seed cake at temperatures ranging from 450 to 600 °C (Shadangi and Singh 2012). The maximal bio-oil yield was approximately 46 %, and it was produced at the temperature of 550 °C. GC–MS analysis showed that the bio-oil contained various compounds. The relative concentrations of the following compounds were high: oleic acid, hexadecanoic acid, octadecanonic acid, octadec-9-enoic acid, hexadecanenitrile, 9-octadecanamide, octadecanamide, phenol, oleanitrile, heptadecane, and pentadecane.

Figueiredo et al. produced bio-oil from the pyrolysis of castor seeds at the temperature of 380 °C (Figueiredo and Romeiro 2009). The product distribution was as follows: 50 wt% bio-oil, 29 wt% bio-char, and 8 wt% gaseous products. The fractions of the bio-oils contained long-chain hydrocarbons and polar compounds.

In the current paper, two types of fruit wastes (cornelian cherry stones and grape seeds) were exposed to pyrolysis under identical conditions. Pyrolysis temperatures from 300 to 800 °C were studied. Product distributions from the pyrolysis of cornelian cherry stones were compared with the pyrolysis of grape seeds under identical conditions. The bio-oils were analyzed via GC–MS and an elemental analyzer. The bio-chars were studied and classified by means of elemental analysis and scanning electron microscopy techniques.