Development of Cellular High-Protein Foods: Third-Generation Yellow Pea and Red Lentil Puffed Snacks.

This study aimed to evaluate how extrusion cooking conditions and microwave heating play a role in enhancing physical and thermal properties of third-generation expanded cellular snacks made from yellow pea (YP) and red lentil (RL) flours for the first time. Increasing temperature and moisture content during extrusion resulted in darker, crunchier and crispier products with higher expansion index (EI). Microwave heating after extrusion led to an increase in cell size and porosity of YP and RL products when qualitatively compared to extrusion alone. Additionally, extrusion followed by microwave heating resulted in extensive damage to starch granular structure and complete denaturation of proteins. Using microwave heating, as a fast and inexpensive process, following partial cooking with extrusion was demonstrated to greatly improve the physical and thermal properties of YP and RL snacks. Microwave heating following mild extrusion, instead of severe extrusion cooking alone, can potentially benefit the development of high quality nutritionally-dense expanded cellular snacks made from pulse flours.

Extrusion cooking of immature rice grain: under-utilized by-product of rice milling process.

Immature rice grain is one of the by-products of paddy milling process. Due to being "whole grain", immature rice grains comprise the fat-rich bran layer which bring along high nutritional value as well as susceptibility to rancidity. Therefore, they are generally used as "feed" rather than "food". In this study, the potential of utilizing immature rice grain as a food ingredient was investigated. For this purpose, raw (unprocessed) and infrared (IR) stabilized immature rice grain flours (IRGF) were extruded at different exit-die temperatures (130 °C and 150 °C) and feed moisture contents (16%, 18%, 20%) and the effects of these parameters on chemical composition (moisture, crude fat, protein, ash, soluble and insoluble dietary fiber and phytic acid contents), physicochemical properties (solubility, water binding capacity, expansion index and bulk density), thiamine, riboflavin and tocopherol contents, textural and sensorial properties of the extrudates were investigated. Either thiamine or tocopherol contents of the extrudates made of unprocessed IRGF were higher than that of the extrudates made of IR stabilized IRGF (p < 0.05). Additionally, higher extrusion temperature and lower feed moisture content resulted in further loss in both vitamins. On the other side, riboflavins showed a relatively heat-stable behavior. Rancid flavor and bitter taste scores of the extrudates which were made of unprocessed IRGF were significantly higher than their counterparts made of IR stabilized IRGF (p < 0.05). Toothpack was the most dominant sensory attribute in all extrudates.

Functional and thermal properties of yellow pea and red lentil extrudates produced by nitrogen gas injection assisted extrusion cooking.

BACKGROUND: There are excellent opportunities for greater incorporation into our diets of pulses, which are rich in proteins and dietary fibers, if their functional properties are modified to fit a wide range of applications in the food industry. The objective of this research was to produce high protein and fiber extrudates from yellow pea and red lentil flours using conventional and N2 gas injection assisted extrusion cooking methods. The effects of process variables on extrudate functional and thermal properties were also investigated. RESULTS: The cold viscosity of extrudates produced by N2 gas injection were higher than those produced by conventional extrusion, indicating that gas-assisted extrusion does affect the end-product pasting properties. At higher barrel temperatures (150-175 °C) extrudates did not exhibit any thermal transition in their thermograms, and thus their starches were completely gelatinized and proteins completely denatured during extrusion. In general, water solubility of extrudates produced by N2 gas injection was significantly (P < 0.05) higher than those produced by conventional extrusion. Emulsion capacity and stability of yellow pea extrudates were in the range of 44-50% and 42-47%, respectively, and the counterpart values of red lentil extrudates were very similar (in the range of 43-47% and 43-46%, respectively). CONCLUSION: Nitrogen gas injection assisted extrusion cooking can be used practically in development of pulse extrudates which contain high protein and dietary fiber. This novel and innovative technique is a reliable alternative method to the conventional CO2 gas injection assisted extrusion cooking methods in the snack food and food ingredient industries. © 2019 Society of Chemical Industry.

Effects of formulation, extrusion cooking conditions, and CO2 injection on the formation of acrylamide in corn extrudates.

BACKGROUND: Acrylamide is a possible carcinogen and known to form in heat-treated carbohydrate-rich foods. This study was designed to investigate the effects of different ingredients (reducing sugars, chemical leavening agents, citric acid), processing conditions (feed moisture content: 22, 24 or 26%, exit die temperature: 110, 150 °C), and extrusion cooking methods (with or without CO2 injection) on acrylamide formation. RESULTS: The type of reducing sugar did not have a considerable effect on acrylamide formation, while increased exit die temperature had a promoting effect. Addition of chemical leavening agents (sodium bicarbonate and ammonium bicarbonate) into formulations increased acrylamide formation levels. The addition of citric acid prevented acrylamide formation, but its effect on textural properties was detrimental. Acrylamide levels of extrudates decreased gradually with increasing feed moisture in all formulations. Acrylamide content of extrudates produced with 22% feed moisture decreased by 61% in the CO2 injection method compared to conventional extrusion. Furthermore, an 82% decrease in acrylamide content was observed with the combined effect of CO2 injection and increasing feed moisture content from 22 to 24% and decreased below the limit of quantification with a further increase in feed moisture. CONCLUSION: A substantial decrease in final acrylamide level is probably due to restriction of two major steps of acrylamide formation: dehydration and decarboxylation.