Extrusion cooking of protein-based products: potentials and challenges.

Extrusion cooking is receiving increasing attention as technology applied for the production of protein-based products. Researchers in this field showed that proteins from several sources are barely consumed because of their poor functionality and lack of acceptability related to the presence of some antinutritional factors. In this regard, extrusion is becoming of key importance thanks to its ability to improve protein functional properties. Based on this remarkable advantage, several studies have been published so far providing evidence of the enhanced functional, physicochemical and sensory properties of protein-based extruded products. The objective of the present review is to give a detailed overview of the potential of extrusion for the production of protein-based products. More specifically, the work describes all the studies published so far on vegetable and animal proteins including those recently released applying the technology on insect proteins. The aspects related to the functional properties of the extrudates together with the quality changes occurring during the process are also described to highlight the potential of the technology for future applications.

High carbon-di-oxide modified atmospheric packaging on quality of ready-to-eat minimally processed fresh-cut iceberg lettuce.

Fresh-cut lettuce is a very well-known salad for today's routines because it obliges minimal preparation to minimize the loss of health beneficial vitamins, minerals, antioxidants and other phytochemicals. It is a prodigious challenge to serve its consumers fresh. Quality of freshly processed lettuce under high CO2 modified atmosphere packaging (MAP) has been investigated as a realistic alternative technique for its preservation. Storage under high CO2 atmospheric treatments exhibited a significant impact in microbial development, electrolyte leakage, volatile metabolites and sensory quality of fresh-cut iceberg lettuce. This storage condition (MAP 1: 5 kPa O2 and 20 kPa CO2 balanced by N2 at 7 °C for 6 days) inhibited the growth of mesophilic bacteria and yeasts; delayed the enzymatic browning (cut-edges and intact surface) of fresh-cut iceberg lettuce and overall visual quality was also in acceptance limit. The development of off-odors was perceived in high CO2 MAP as a consequence of volatiles (ethanol and acetaldehyde) accumulation which was persisted at an inexcusable level during 6 days of storage periods.

Effect of Pulsed Electric Field Pretreatment on Drying Kinetics, Color, and Texture of Parsnip and Carrot.

The aim of the study was to evaluate the effect of pulsed electric field (PEF) pretreatment on drying kinetics and on color and textural changes in sliced parsnip and carrot. Cell disintegration index measured in parsnips after PEF pretreatment significantly differed from the ones measured for carrots and, consequently, the reduction of the time needed to dry both samples to a final moisture content up to 5% (wet basis). The drying time of the PEF pretreated parsnip was reduced by up to 28% at 70 °C and by up to 21% at 60 °C in carrot, in comparison to untreated samples. The PEF pretreatment influenced the effective diffusivity of water into the samples going from 50 °C to 70 °C: in carrots it ranged between 1.61 × 10-10 and 3.04 × 10-10 (m2 /s), although, in parsnip, it ranged between 1.97 × 10-10 and 3.06 × 10-10 (m2 /s). Also, PEF pretreatment influenced color changes: PEF pretreated dried carrots showed a significant (p < .05) reduction in lightness values (L* ) compared to untreated dried ones, although PEF pretreated parsnip had a significant (p < .05) increase in redness values (a* ). The PEF treatment did not affect the mechanical properties (p > .05) of carrot and parsnip dried at 50 and 60 °C, whereas at 70 °C a significant increase (p < .05) of the force required to cut both root slices was detected. The choice of a PEF pretreatment of foods to be dried should be related to shorten the drying time and to minimize the loss in quality properties mentioned above. PRACTICAL APPLICATION: Dry carrots and parsnip slices can be used as food ingredients for further food preparations but also as healthy snacks, thanks to their health benefits. Pulsed electric field (PEF) resulted to be an effective pretreatment for carrots and parsnips before undergoing convective drying, because it reduced the drying time (up to 28% in parsnip and 21% in carrot slices) and, particularly at mild temperatures (50 to 60 °C), it did not affect the texture properties of both carrot and parsnip. PEF pretreatment of these roots before convective heating can be surely suggested as industrial application.