Improve the convenience of prepared meat, cereal, vegetable foods.

Demographic changes, social pressures and work practices have kept food preparation to a minimum. Consumers are demanding high-quality, tasty and safe foods that can be prepared in minutes. Minimal processing is in demand. Understanding the functionality of meat proteins and nonmeat ingredients is essential for producing high-quality, minimally processed consumer products and for the development of new meat products.

European scientists are addressing the minimal processing issue. They set out to investigate the effects of heating foods in microwave ovens. They also examined extruded and cooked meat-cereal combinations, and they looked at the distortion of flexible containers during thermal sterilization.

For example, researchers found that temperatures achieved during and after reheating products in the microwave differ significantly between potato systems. In this instance, the temperatures are based on the levels of moisture, fat and salt in the treatments. The thermal conductivity of the potato treatments varied with moisture content at 20 C and with the percentage moisture and salt at 60 C. The level of fat in the mashed potato had no significant effect on the thermal conductivity. The thermal diffusivity of the mashed potato decreased with increasing fat levels and increased with increasing salt levels. The moisture levels did not cause a change in the thermal diffusivity of the mashed potato treatments.

Meanwhile, the main focus of the work on extrusion involved studying the influence of the variables in the extrusion process on the quality of product. In order to do this, scientists had to develop a reasonably priced recipe that would give a dry, shelf-stable, readily reconstitutable, chunk-type product. Various combinations of meat and baker's flour, gluten, soy protein isolate, soy protein concentrate, and potato and maize starches were evaluated. A combination of meat and soy flour gave the most satisfactory results.

Three recipes were extruded: a control (soy flour and water), a myofibrillar (lean) meat containing 25% meat and 75% soy flour, and a connective tissue formulation that had 25% connective tissue and 75% soy flour. These recipes were chosen to evaluate and compare the performance of lean meat, connective tissue and soy flour in a high-temperature shear environment in an extruder. Researchers found the connective tissue recipe was more heat-stable.

In the flexible container project, researchers established the effectiveness of a deflection sensor in detecting movement of the flexible surface of a container during thermal processing. As expected, when a product was filled into the container at room temperature, the tendency to distort increased as fill weight increased. Hot filling produced a partial vacuum in the containers and, in the samples examined, reduced the distortion caused by increased fill.

Scientists also examined the authenticity of consumer foods. In one instance, dried drip juice from commercial samples was analyzed using infrared spectroscopy to try to distinguish drip from fresh or frozen, then thawed meat. Results so far confirm the potential of this procedure for industrial use.

Further information. Tom Doyle, The National Food Center, Castleknock, Dublin 15, Ireland; phone: [phone]; fax: [phone]; email: [e-mail].