Viswas Ghorpade

Chemically Modified Soy Protein Films

Glycerin-plasticized soy protein films were produced by casting heated alkaline (pH 8.5) protein solutions. Acetic anhydride, succinic anhydride, calcium cations, and formaldehyde were added to the film-forming solutions and their effects on film water solubility (WS), tensile strength (TS), puncture strength (PS), water vapor permeability (WVP), and oxygen permeability (OP) were determined. Acylation with acetic and succinic anhydrides increased film WS without affecting other film properties. Treatment with calcium cations increased TS and PS by 96 and 43%, respectively, but did not change film barrier properties. Formaldehyde resulted in larger than two-fold increases in TS and PS, while reducing WS and WVP. As a trade-off, formaldehyde treated films were more permeable to oxygen.

Heat Curing of Soy Protein Films

Modification of soy protein film properties by heat-curing was studied. Glycerin-plasticized films were cast from alkaline aqueous solutions of soy protein isolate. Films were heated at 80 or 95°C for 2, 6, 14, or 24 h. Tensile strength (TS), elongation at break (E), moisture content (MC), water solubility (WS), water vapor permeability (WVP), and color of heated and control films were measured. Heated films had increased TS and +b (yellowness) Hunter color values and reduced E, MC, WS, and WVP values. These effects were enhanced as heating time and temperature increased.

Laboratory composting of extruded poly(lactic acid) sheets

Composting of extruded poly(lactic acid) (PLA) in combination with pre-composted yard waste in a laboratory composting system was studied. Yard waste and PLA mixtures containing 0%, 10%, or 30% PLA (dry weight basis) were placed in composting vessels for four weeks. Exhaust gases were analyzed for carbon dioxide concentration twice per week. After the first week, significantly greater (P < 0.05) amounts of carbon dioxide were generated in vessels with 10% or 30% PLA than in control (0% PLA) vessels. Data indicated that microbial degradation of PLA occurred. There was no significant difference (P > 0.05) in carbon dioxide emission between 10% and 30% PLA mixtures. Compost pH dropped (from 6.0 to 4.0) after 4 weeks of composting for 30% PLA, but remained unchanged (6.3) for 0% or 10% PLA. Most likely, in the case of 30% PLA, substantial chemical hydrolysis and lactic acid generation lowered the compost pH. The lowered pH likely suppressed microbial activity, thus explaining the lack of difference in carbon dioxide emissions between 10% and 30% PLA mixtures. Gel permeation chromatography showed a notable decrease in PLA molecular weight as a result of composting. It was demonstrated that PLA can be efficiently composted when added in small amounts (<30% by weight) to pre-composted yard waste.

Properties of thermally-treated wheat gluten films☆

Effects of thermal treatments on selected properties of wheat gluten film were studied. Films were cast from heated alkaline aqueous solutions of wheat gluten, ethanol and glycerin and subsequently heat treated at 65, 80, or 95 °C for 2, 4, 6, 12, 18, or 24 h. Water vapor permeability (WVP), Hunter L, a and b values, tensile strength (TS) and elongation at break (E) were determined and compared with untreated film (control). Significant reduction in WVP of film occurred with increasing curing temperature and exposure time. Hunter L value (whiteness) decreased, whereas a (redness) and b (yellowness) values increased with increasing heat treatment temperature and exposure time. Also, an increase in TS and a decrease in E were present with increasing treatment temperature and exposure time.

Industrial Applications for Levulinic Acid

Levulinic acid has been produced since 1870. Over the years the basic chemistry and properties have been studied extensively. Though levulinic acid has significant potential as an industrial chemical, it has never reached commercial use in any significant volume. A reason for non-commercialization of this chemical may be that most of the research was done in early 40’s, when the raw materials were expensive, yield was low, and equipment for separation and purification was lacking. Today, overproduction of raw materials and developments in science and technology have opened doors to reevaluate industrial potential of a forgotten chemical giant, levulinic acid. Levulinic acid can be produced by high temperature acid hydrolysis of carbohydrates, such as glucose, galactose, sucrose, fructose, chitose and also from biomeric material such as wood, starch and agricultural wastes. Isolation of levulinic acid can be accomplished either by partial neutralization, filtration of humin material and vacuum steam distillation, or by solvent extraction. Levulinic acid is a highly versatile chemical with several industrial uses. Literature shows potential uses as resin, plasticizer, textile, animal feed, coating, and as an antifreeze. At the University of Nebraska-Lincoln, efforts are being made to prepare levulinic acid using an extruder as a continuous reactor and possible use as an antifreeze ingredient. This antifreeze will have definite advantages over ethylene glycol. It will be non-toxic and easily digestable by microorganisms. The antifreeze ingredient will be in solid form, hence it will be marketed more readily than liquid forms.

Mechanical and Barrier Properties of Wheat Gluten Films Coated with Polylactic Acid

Development of biopolymer films and coatings from protein, polysaccharide, and lipid materials has received increased interest in recent years. In the midst of rising concerns over solid packaging waste and dwindling petroleum reserves, the renewable and degradable nature of biopolymer fiilm ingredients make such fiilms particularly appealing for innovative uses in the fiield of packaging. However, unlike some proteins, few nonfood applications for wheat gluten have been developed. In 1990 world wheat production was 589 million metric tonnes, of which 12.6% was produced in the US. Industrial Uses of Agricultural Materials (June, 1993) reported consolidated sales for low density polyethylene (LDPE) at about 3.1 million metric tonnes for various food and nonfood packaging uses in the US in 1992. The total LDPE sales, agricultural uses and trash bags sales accounted for 770,000 metric tonnes in 1992. A 30% market penetration of wheat gluten polymer in agricultural mulches and trash bags would use around 230,000 metric tonnes of gluten in the US alone.