Pre-gelatinized high-amylose starch enables easy preparation of flexible and antimicrobial composite films for fresh fruit preservation.

While high-amylose starch (HAS) possesses advantageous properties such as high resistant starch content and favorable mechanical attributes, its gelatinization constraints have limited its applicability. This study enhances its versatility by focusing on pre-gelatinized (PG) HAS with exceptional rehydratability, achieved by disorganizing native HAS granules (with amylose contents of 55 % and 68 %, respectively) using a 33 % CaCl2 solution, followed by water-ethanol precipitation and freeze-drying. The resulting PG-HAS exhibited elevated amylose content (61 % and 75 %) with minimal changes in amylose molecular weight. PG-HAS displayed superior water-absorption index (WAI) and water-soluble index (WSI) compared to native HAS, further improved by 2 % CaCl2 solution incorporation. Furthermore, composite films were prepared by mixing PG-HAS with PVA at a 6:4 (w/w) ratio. The PG-G50 (61 % amylose content)/PVA composite film exhibited remarkable elongation (131.1 ± 5.4 %), nearly three times that of a normal corn starch (NCS, with 27 % amylose)/PVA film, attributed to improved starch dispersity and higher amylose content. Nonetheless, the PG-G70 (75 % amylose content)/PVA film at the same ratio showed lower elongation (54.7 ± 8.0 %), potentially due to strong cohesive forces between amylose chains that impede starch-PVA interactions. Moreover, the PG-HAS/PVA composite films, enriched with antibacterial agents, demonstrated effective antibacterial properties with a gradual and sustained release of active compounds. Notably, the PG-G50/PVA/tannic acid (TA) film effectively preserved fresh apple slices by inhibiting bacteria growth and preventing browning. These findings underscore the excellent rehydration of PG-HAS and its potential as an inner packaging material for irregularly shaped foods, such as sliced fruits or meats, due to its nontoxic nature, softness and flexibility, which allows the film to maintain close contact with food surfaces.

An environmental monitoring data sharing scheme based on attribute encryption in cloud-fog computing.

Environmental monitoring plays a vital role in environmental protection, especially for the management and conservation of natural resources. However, environmental monitoring data is usually difficult to resist malicious attacks because it is transmitted in an open and insecure channel. In our paper, a new data sharing scheme is proposed by using attribute-based encryption, identity-based signature and cloud computing technology to meet the requirements of confidentiality, integrity, verifiability, and unforgerability of environmental monitoring data. The monitoring equipment encrypts the monitored environmental data and uploads it to the environmental cloud server. Then, monitoring users can request access to the environmental cloud server. If the monitoring user meets the access policy, the plaintext is finally obtained through the fog node decryption. Our proposal mainly uses attribute-based encryption technology to realize the privacy protection and fine-grained access control of monitoring data. The integrity and unforgeability of the monitoring data are ensured by the digital signature. In addition, outsourcing computing technology saves the computing overhead of monitoring equipment and monitoring users. The security analysis illustrates that our proposal can achieve security purposes. Finally, the performance of our proposal and related schemes is evaluated from the aspects of communication overhead and computing overhead. The results indicate that our proposal is secure and efficient in environmental monitoring.