Chitosan effects on physical properties, texture, and microstructure of flat rice noodles

Effects of debranched starch on physicochemical properties and in vitro digestibility of flat rice noodles

Aiming to develop flat rice noodles with both desirable textural quality and lower starch digestibility, we investigated the effect of adding indica rice debranched starch (RDBS) on the quality of flat rice noodles. In this study, adding RDBS to flat rice noodles enhanced their mechanical properties. Cooking characteristic analysis showed that incorporating RDBS into dried flat rice noodles increased the rehydration ratio by 16.1 % and reduced rehydration time by 26.5 %. Scanning electron microscopy (SEM) revealed the presence of microparticles formed through the self-assembly of RDBS within the network of flat rice noodles. X-ray diffraction (XRD) analysis demonstrated that the addition of RDBS elevated the crystallinity of the flat rice noodles, rising from 9.59 % to 22.57 %. In addition, the in vitro simulated digestion test suggested the addition of RDBS led to a threefold increase in the content of slowly digestible starch (SDS) and a ninefold increase in resistant starch (RS) content in flat rice noodles. This study found that adding RDBS into flat rice noodles can effectively reduce their digestion rate and improve their eating quality. It could be a promising approach for creating functional rice noodles aimed at alleviating public health concerns such as diabetes and obesity.

Ordered structural changes of retrograded instant rice noodles during the long-term storage

Temperature-induced textural, cooking properties and structural variations of retrograded instant rice noodles (IRN) during the long-term storage were systematically investigated. IRN samples stored at 4 °C exhibited a relative high cooking loss (2.45 %), and their hardness values gradually increased with prolonged storage. Moreover, the higher storage temperature (35 °C) accelerated the deterioration of IRN texture. Fresh IRN displayed a typical B-type XRD pattern with 9.65 % relative crystallinity (RC). During the initial 2 weeks of storage, the formation of a long-range ordered structure led to an increase in RC, which was closely related to the duration and temperature of storage (ranging from 4 °C to 25 °C to 35 °C). Over the 12-week storage period, there was likely a disorganization of the supra-molecular structure, as evidenced by the considerably decreased RC and reduced water mobility. Furthermore, Pearson's correlation analysis highlighted that the tight integration between starch molecules and water molecules endowed IRN samples with enhanced smoothness and tenderness in flavor profiles. Hence, the study is expected to provide a comprehensive understanding of the mechanisms underlying molecular order changes in retrograded starch gel products during the long-term storage.

Effect of carboxymethyl chitosan on the storage stability of frozen dough: State of water, protein structures and quality attributes

Carboxymethyl chitosan (CMCh), an ampholetic chitosan derivative, has found broad applications in the food industry. However, its cryo-protective properties remained less explored compared to other viscous polysaccharides, such as carboxymethyl cellulose, carrageenan etc., which have been widely utilized as frozen food additives. In this study, we investigated the effect of CMCh addition to frozen dough in terms of water state, protein structure, and the textural properties of prepared frozen dumpling wrappers. Results indicated that CMCh restricted the water migration in dough and delayed protein deterioration during frozen storage. Specifically, the content of freezable water in dough was reduced and the water distribution became more uniform as reflected by DCS and LF-NMR analysis. CMCh also stabilized disulfide bond and secondary structures of the protein, leading to inhibition of dough rheology changes. Accordingly, the obtained frozen dumplings wrappers demonstrated decreased cracking rate and water loss, and improved textural properties. Moreover, CMCh with higher degree of carboxymethyl substitution (DS: 1.2, CMCh-B) exhibited better cryo-protective effects compared to CMCh of lower DS (DS: 0.8, CMCh-A). Our study provides novel insights and scientific basis for the development of ampholetic polysaccharides as high-performance food additives.

Improving the Quality of Frozen Fillets of Semi-Dried Gourami Fish (Trichogaster pectoralis) by Using Sorbitol and Citric Acid

Semi-dried gourami fish (Trichogaster pectoralis) is popularly consumed domestically and exported as a frozen product. This study was conducted to prevent deterioration quality in frozen fish fillets during storage. This research aims to investigate the effects of sorbitol and citric acid at concentrations of 2.5% and 5% (w/w) of frozen gourami fish fillets compared to the fillets soaked in distilled water on physicochemical properties, such as cooking loss, cooking yield, drip loss, pH, TBARS, color, and texture profile analyses (TPA) during storage at -18 ± 2 °C for a period of 0, 20, and 40 days. The fish soaked in sorbitol and citric acid solutions had significantly (p < 0.05) higher protein and fat contents than the control sample. Sorbitol was able to retain moisture in the product; therefore, the drip loss and cooking loss were the lowest, and cooking yield was the highest among other samples (p < 0.05). The addition of 5% (w/v) citric acid in frozen fish fillets can significantly retard the thiobarbituric acid reactive substance (TBARS) (p < 0.05) during storage when compared to fish soaked in sorbitol solution kept for the same period. However, the addition of citric acid resulted in low quality in texture and color of frozen fish fillets. The use of sorbitol was the best alternative in frozen fish fillet product due to reducing the negative effects of freezing quality of the products and generating a cryoprotective effect compared to the fillets soaked in distilled water.

Chitosan as a Valuable Biomolecule from Seafood Industry Waste in the Design of Green Food Packaging

Chitosan is a versatile biomolecule with a broad range of applications in food and pharmaceutical products. It can be obtained by the alkaline deacetylation of chitin. This biomolecule can be extracted using conventional or green methods from seafood industry residues, e.g., shrimp shells. Chitin has limited applications because of its low solubility in organic solvents. Chitosan is soluble in acidified solutions allowing its application in the food industry. Furthermore, biological properties, such as antioxidant, antimicrobial, as well as its biodegradability, biocompatibility and nontoxicity have contributed to its increasing application as active food packaging. Nevertheless, some physical and mechanical features have limited a broader range of applications of chitosan-based films. Green approaches may be used to address these limitations, leading to well-designed chitosan-based food packaging, by employing principles of a circular and sustainable economy. In this review, we summarize the properties of chitosan and present a novel green technology as an alternative to conventional chitin extraction and to design environmentally friendly food packaging based on chitosan.

Study on the shelf life and quality characteristics of highland barley fresh noodles as affected by microwave treatment and food preservatives

In this work, the effect of microwave (MW), ε-poly-L-lysine (ε-PL), calcium propionate (CP), and their combinations on the shelf life and quality characteristics of highland barley fresh noodle (HBFN) was studied. Firstly, the mixed flour was treated by MW (800 W) for different time. Subsequently, HBFN was prepared by mixing flour and sterilized water with addition of 0.04% ε-PL combined with different concentrations of CP (0.025%, 0.020%, 0.015%) and stored at 25 ± 1°C. Changes of total plate count (TPC), moisture content, water state, textural properties, color, and pH in HBFN were monitored during storage. The results indicated that microwave treatment (40 s) provided 30% reduction of initial TPC of the flour without decline of noodle quality. Shelf life of HBFN treated with MW + ε-PL (0.04%) + CP (0.02%/0.025%) reached 80 and 88 hr, respectively, and had good edible qualities during storage.