Evaluation of air‐dried soy protein isolate‐rice noodles prepared via combined treatment with microbial transglutaminase and glucono‐δ‐lactone

Acceleration mechanism of the rehydration process of dried rice noodles by the porous structure

Rehydration of dried rice noodles (DRNs) is a time-consuming process, which is dominated by the compactness of noodle structure. Therefore, DRNs with differentiated porous structures were prepared, and their effect on the rehydration process was investigated. Porous structure can shorten rehydration time by reducing the time needed for water to migrate into the noodle core, or the water amount required for rehydration. Magnetic resonance imaging showed that although larger pores facilitate absorbing more water, the time for water to migrate into the noodle center is longer than that of medium size pores, as water needs to fill the periphery large hole before inward migration. SAXS analysis demonstrated that the presence of flexible starch molecular chains reduce the water required to achieve the maximum tensile strain of samples, thus shortening the rehydration time. Understanding the acceleration mechanism of porous structure on rehydration contributes to designing improved process of instant noodle products.

Improvement of cooking and textural properties of rice flour-soy protein isolate noodles stabilised with microbial transglutaminase and glucono-δ-lactone and dried using superheated steam

In a bid to produce rice flour noodles with improved texture and reduced cooking time, rice flour-soy protein isolate noodles (RNS) were structurally enhanced by a combined treatment (COM) of microbial transglutaminase (MTG) with glucono-δ-lactone (GDL). The RNS-COM was either dried using superheated steam (SHS) to yield RNS-COM-SHS or steamed for 10 min (S10) before air drying to produce RNS-COM-S10 noodles. Control samples were SHS-dried rice flour (RN-SHS) and air-dried RN-S10 noodles. In general, textural and microstructural properties indicated higher textural properties and a more robust network in RNS-COM-SHS and RNS-COM-S10 than in other noodles. However, optimum cooking time (P < 0.5) was in the order; RN-SHS, RNS-COM-SHS < RN-S10 < RNS-COM-S10. As a result of the COM treatment, structurally enhanced noodles were more resistant to cooking. As applied in RNS-COM-SHS noodles, SHS was able to improve cooking quality, probably through the formation of bigger and evenly spread pores that had promoted faster gelatinisation of starch, with a high order of relative starch crystallinity.

The modulatory roles and regulatory strategy of starch in the textural and rehydration attributes of dried noodle products

Noodles are popular staple foods globally, and dried noodle products (DNPs) have gained increasing attention due to recent changes in consumer diet behavior. Rapid rehydration and excellent texture quality are the two major demands consumers make of dried noodle products. Unfortunately, these two qualities conflict with each other: the rapid rehydration of DNPs generally requires a loose structure, which is disadvantageous for good texture qualities. This contradiction limits further development of the noodle industry, and overcoming this limitation remains challenging. Starch is the major component of noodles, and it has two main roles in DNPs. It serves as a skeleton for the noodle in gel networks form or acts as a noodle network filler in granule form. In this review, we comprehensively investigate the different roles of starch in DNPs, and propose strategies for balancing the conflicts between texture and rehydration qualities of DNPs by regulating the gel network and granule structure of starch. Current strategies in regulating the gel network mainly focused on the hydrogen bond strength, the orientation degree, and the porosity; while regulating granule structure was generally performed by adjusting the integrity and the gelatinization degree of starch. This review assists in the production of instant dried noodle products with desired qualities, and provides insights into promising enhancements in the quality of starch-based products by manipulating starch structure.