Stepwise optimisation of enzyme production in solid state fermentation of waste bread pieces

Glucoamylase production from food waste by solid state fermentation and its evaluation in the hydrolysis of domestic food waste

“…Lower initial moisture content provided lower solubility of the nutrients while higher moisture contents resulted in decreased porosity and gas exchange. The moisture content range was consistent with the levels reported in the literature for SSF of waste bread and wheat flour by A. awamori (Wang et al, 2009;Melikoglu et al, 2013a). Generally, the initial pH for GA production by A. awamori using SSF is adjusted to neutral pHs as the fungus grows well at such pHs.…”

“…Generally, the incubation time is governed by characteristics of the culture, its growth rate and enzyme production. Maximum GA production normally occurs after 2-5 d of incubation as reported by other researchers working with solid state cultures involving bacteria and fungi (Soni et al, 2003;Melikoglu et al, 2013a). The fungus used in the present study colonized well on the waste materials, and exhibited a good growth on the surface after 24 h. The high reducing sugars in cake, fruit and potato wastes may have triggered the GA production, so it was higher than savory and MFW on day 1.…”

“…After sieving, the moisture content was adjusted to 70% wt. and the SSF was carried out with an inoculum loading of 10 6 spores/g substrate at neutral initial pH and 30 o C for 4 d as these conditions were reported as optimum for GA production from A. awamori by SSF by Melikoglu et al (2013a).…”

“…The experimental range and the levels of the variables are defined and presented in Table 1. The ranges of variables used in this work were selected based on the literature (Ellaiah et al, 2002;Melikoglu et al, 2013a;Wang et al, 2009;Pandey, 1991).…”

“…Although glucoamylases have been produced by submerged fermentation traditionally, solid state fermentation (SSF) processes have been increasingly applied for the production of this enzyme in recent years (Ellaiah et al, 2002). SSF has advantages over submerged fermentation in that it is simpler, requires less capital, has superior productivity, lower energy requirement, requires simpler fermentation media, does not require rigorous control of fermentation parameters, uses less water, produces less waste water, allows for the easy control of bacterial contamination, and has a lower downstream processing cost (Ellaiah et al, 2002;Anto et al, 2006;Melikoglu et al, 2013a). However, the scale up of the SSF is a great challenge due to hardship of mixing, difficulty of heat removal and restricted water content which cause rapid change of moisture.…”