Farhad Ahmadi

Investigation of gelatin/multi-walled carbon nanotube nanocomposite films as packaging materials

Gelatin composite films were prepared from gelatin solutions (10% w/v) containing multi-walled carbon nanotubes (MWCNT, 0.5, 1, 1.5, and 2% w/w gelatin) as nanofiller. The water solubility, water swelling, water uptake, water vapor permeability (WVP), mechanical, and antibacterial properties of the films were examined. Water solubility, water swelling, water uptake, and WVP for gelatin films were 45 ± 1%, 821 ± 42%, 45 ± 1.1%, and 0.4 ± 0.022 g mm/m2 kPa h, respectively. Incorporation of MWCNT caused a significant decrease in water solubility, water swelling, water uptake, and WVP. Gelatin/MWCNT films containing 1–1.5% MWCNT showed the lowest water vapor transmission. Tensile strength, elongation at break, and Youngs modulus for gelatin films were 13.4 ± 1.2 MPa, 95 ± 5%, and 45.4 ± 7 MPa, respectively. Incorporation of MWCNT caused a significant increase in tensile strength and decrease in the elongation at break. The largest mechanical strength was found at 1.5% MWCNT. All gelatin/MWCNT films showed significant antibacterial activities against both gram-positive and gram-negative bacteria. Our results suggest that the gelatin/MWCNT composites films could be used as a very attractive alternative to traditional materials for different biomedical and food applications.

Short-term oxidative lime pretreatment of palm pruning waste for use as animal feedstuff.

BACKGROUND Oxidative lime pretreatment (OLP) is an effective pretreatment for highly recalcitrant lignocellulosic materials. This experiment was conducted to investigate the effect of short-term OLP on fermentative gas production kinetics of date palm prunings. Rachis and petiole were pretreated with excess lime (0.5 g Ca(OH)2 g(-1) dry matter) in a reactor charged with 10 bar pure oxygen pressure at different times and temperatures. RESULTS Lignin removal was greatly affected by OLP, whereas cellulose was well preserved even after severe pretreatment. After 72 h fermentation, the cumulative gas production was 321.2 mL gas g(-1) organic matter (OM) for the most severe pretreatment, compared to 73.6 mL g(-1) OM for the untreated rachis. For the petiole pretreated at 120 °C for 280 min, 268 mL gas was produced compared to 59 mL gas g(-1) OM for the untreated petiole. Scanning electron microscope images showed the formation of pores (average diameter of 10-12 µm) and carbonate calcium deposits on the surface of treated biomass. An increase in biomass crystallinity was observed in pretreated samples resulting from cellulose enrichment. CONCLUSIONS The results suggest that OLP improves the ruminal digestibility of date palm prunings, which may have potential for inclusion in the ruminant diet at low cost.

Pre-treatment of sugarcane bagasse with a combination of sodium hydroxide and lime for improving the ruminal degradability: optimization of process parameters using response surface methodology

A three-factor, three-level, face-centred cubic design was adopted to investigate the effect of three pre-treatment parameters, namely sodium hydroxide-to-dry biomass ratio [0.00, 0.05, and 0.10 (w/w)], lime-to-dry biomass ratio [0.00, 0.05, and 0.10 (w/w)] and residence reaction time (24, 96, and 168 h), at moderate temperature (21°C) on 24-h cumulative gas production (GP24) and delignification, as the response variables. Under the optimal pre-treatment conditions of NaOH-to-dry biomass ratio of 0.09 (w/w), lime-to-dry biomass ratio of 0.09 (w/w) and residence time of 160.3 h, the model predicted 151.6 mL gas/g organic matter (OM) versus the experimental value of 147.2 mL gas/g OM. Under the optimal conditions of NaOH-to-dry biomass ratio of 0.10 (w/w), lime-to-dry biomass ratio of 0.08 (w/w) and residence time of 156.8 h, sugarcane bagasse (SCB) was maximally delignified by 41.2%, whereas the model predicted 43.6% delignification. Under the optimal conditions determined for GP24, the neutral detergent fibre degradability of the pre-treated biomass after 24 and 48 h was 37.2 and 56.3%, respectively, a 1.90-fold and 1.58-fold over the untreated biomass, respectively. Overall, it was found that combined alkali treatment at optimal conditions effectively enhanced the ruminal degradability of SCB.

The effect of lime pre-treatments of date palm leaves on delignification and in vitro rumen degradability

Experiments were conducted to determine the effect of lime pre-treatment on the chemical composition and in vitro rumen degradability of date palm leaves (DPL). Lime pre-treatments, with or without oxygen supply, were applied for 1, 2 and 3 weeks at 25 and 40 °C. Lime was neutralized by the Calcium-Capturing-by-Carbonation process. Delignification and in vitro rumen gas production were significantly influenced by duration, temperature and oxygen. At 40 °C, oxygen presence stimulated more delignification and subsequently increased in vitro rumen degradability. Lime pre-treatment with 0·2 g calcium hydroxide (Ca(OH) 2 )/g dry biomass for 3 weeks at 40 °C in the presence of oxygen resulted in a 3-fold increase in gas production after 24 h of incubation, compared with untreated biomass. Lime treatment of DPL with aeration resulted in higher lignin removal and subsequent rumen degradability than without aeration. A techno-economic analysis is needed to select the most efficient and economically feasible pre-treatment procedure.

Preservation of fruit and vegetable discards with sodium metabisulfite

Two series of experiments were performed to investigate the aerobic preservation of fruit and vegetable discards (FVD) using sodium metabisulfite (SMB). In Exp. 1, metabisulfite was applied at 0, 2, 4, 6, and 8 g/kg FVD for 0, 3, 6, 9, and 12 d. Metabisulfite treatment at 6 and 8 g/kg FVD was highly effective in controlling putrefaction and preserving the nutrient components for 6 and 9 d, respectively. In the pilot-scale experiment (Exp. 2), SMB was applied at 0 and 8 g/kg FVD in a 600-L bucket for 0, 6, and 9 d in an outdoor environment. The SMB treatment was highly effective in maintaining the integrity and freshness of FVD, suppressing microbial proliferation, and preserving the nutrient constituents. Under the conditions of this study, SMB effectively preserved FVD in an aerobic environment, enabling their more efficient long-term recycling through livestock feed or development of value-added products.