A semen cassia gum-based film with visual–olfactory function for indicating the freshness change of animal protein-rich food

Enzymatically green-produced bacterial cellulose nanoparticle-stabilized Pickering emulsion for enhancing anthocyanin colorimetric performance of versatile films

To enhance the colorimetric performance of anthocyanin (Ant), a konjac glucomannan (KGM)-based multifunctional pH-responsive indicator film was fabricated by introducing enzymatically prepared bacterial nanocellulose (EBNC) stabilized camellia oil/camellia essential oil Pickering emulsion (BCCE). Specifically, optimized enzymatic hydrolysis time (36 h) was determined based on the particle size and microstructure. Then BCCE (containing 0.4% EBNC) was incorporated into Ant-containing KGM, and the novel active indicator film (KGM-Ant-BCCE) was constructed. Films with varying BCCE concentrations (3%-11%) exhibited enhanced UV shielding, thermal stability, mechanical strength, water vapor and oxygen permeability, hydrophobicity, and antioxidant performance. The pronounced color change of KGM-Ant-BCCE indicated its potential for visually detecting shrimp freshness. Moreover, the biodegradability (25 days) confirmed the environmentally benign property of the film. In summary, incorporating green-produced EBNC nanoparticle-stabilized BCCE offers an innovative pathway to improve the color indication capability of polysaccharide-based smart packaging.

Novel pH-responsive indicator films based on bromothymol blue-anchored chitin for shrimp freshness monitoring

The cellulose nanofibers (CNFs) based pH-sensitive indicator films were developed by mixing guar gum (GG) with bromothymol blue-anchored chitin (BTB-Chitin) as an indicator to monitor shrimp freshness. The BTB-Chitin was prepared by grafting hydroxypropyltriethylamine groups (HPTA) to chitin first, then anchoring bromothymol blue (BTB) to prepare intelligent pH response BTB-Chitin. The 0.08 BTB-Chitin films had a good tensile strength of 11.76 MPa and the water contact angle values were 125°, which displayed obvious color response to pH buffers and acid base volatile gas. Besides, the homogeneous and flexible composite films showed good color stability and reversibility. The released amount of BTB was very low from the BTB-Chitin films in heptane and corn oil. The composite films had been degraded completely in 15 days in soil. The pH and volatile base nitrogen were measured to determine the degree decay of shrimp (Litopenaeus vannamei), and the prepared pH-sensitive films changed from yellow (fresh) to cyan (spoiled) with the freshness of shrimp decreased, indicating the BTB-Chitin films could detect the shrimp freshness in real-time and high visibility.

The colorful world of sulfonephthaleins: Current applications in analytical chemistry for "old but gold" molecules

Sulfonephthaleins represent one of the most common and widely employed reactive dyes in analytical chemistry, thanks to their stability, low-cost, well-visible colors, reactivity and possibilities of chemical modification. Despite being first proposed in 1916, nowadays, these molecules play a fundamental role in biological and medical applications, environmental analyses, food quality monitoring and other fields, with a particular focus on low-cost and disposable devices or methods for practical applications. Since up to our knowledge, no reviews or book chapters focused explicitly on sulfonephthaleins have ever been published, in this review, we will briefly describe sulfonephthaleins history, their acid-base properties will be discussed, and the most recent applications in different fields will be presented, focusing on the last ten years literature (2014-2023). Finally, safety and environmental issues will be briefly discussed, despite being quite controversial.

A comprehensive review of the spoilage of shrimp and advances in various indicators/sensors for shrimp spoilage monitoring

Shrimp is a popular internationally traded shellfish due to its unique taste, texture, and nutritional value. Shrimp is highly perishable because it has enough free amino acids, high moisture levels, non-nitrogenous compounds used for microbial growth, and melanosis. Shrimp spoilage after death is caused by various reasons, like autolysis (endogenous proteinases actions during shrimp storage), growth of spoilage microorganisms, ATP degradation, melanin formation, and lipid peroxidation. A microbial byproduct, total volatile basic nitrogen, is one of the major reasons for the generation of foul odors from shrimp spoilage. Shrimp freshness monitoring is crucial for market sellers and exporters. Traditional methods for estimating shrimp freshness are expensive and inaccessible to the general public. Sensors are rapid, sensitive, selective, and portable food toxins' detection tools, devoid of expensive instruments, skilled people, sample pretreatment, and a long detection time. This review addresses shrimp spoilage causes. The mechanisms of different stages of shrimp spoilage after death, like rigor mortis, dissolution of rigor mortis, autolysis, and microbial spoilage mechanisms, are discussed. This review highlights the last five years' advances in shrimp freshness detection sensors and indicators like colorimetric pH indicators, fluorescence sensors, electronic noses, and biosensors, their working principles, and their sensitivities. Commercially available indicators and sensors for shrimp spoilage monitoring are also discussed. A review highlighting the applications of the different sensors and indicators for monitoring shrimp freshness is unavailable to date. Challenges and future perspectives in this field are explained at the end.

An antibacterial and intelligent cellulose-based label self-assembled via electrovalent bonds for a multi-range sensing of food freshness

Intelligent labels provide customers with food freshness information. However, the existing label response is limited and can only detect a single kind of food. Here, an intelligent cellulose-based label with highly antibacterial activity for a multi-range sensing freshness was developed to overcome the limitation. Cellulose fibers were modified using oxalic acid to graft -COO^- followed by binding chitosan quaternary ammonium salt (CQAS), the remaining charges of which attached methylene red and bromothymol blue to form response fibers and to further self-assemble into the intelligent label. CQAS electrostatically gathered the dispersed fibers, resulting in an increase in TS and EB of 282 % and 16.2 %, respectively. After that, the rest positive charges fixed the anionic dyes to broaden pH response range of 3-9 effectively. More significantly, the intelligent label exhibited highly antimicrobial activity, killing 100 % of staphylococcus aureus. The rapid acid-base response revealed the potential for practical application in which the label color from green to orange represented the milk or spinach from fresh to close to spoiled, and from green to yellow, and to light green indicated the pork fresh, acceptable, and close to spoiled. This study paves a way for the preparation of intelligent labels in large-scale and promote the commercial application to improve food safety.

Progress in the Development of Detection Strategies Based on Olfactory and Gustatory Biomimetic Biosensors

The biomimetic olfactory and gustatory biosensing devices have broad applications in many fields, such as industry, security, and biomedicine. The development of these biosensors was inspired by the organization of biological olfactory and gustatory systems. In this review, we summarized the most recent advances in the development of detection strategies for chemical sensing based on olfactory and gustatory biomimetic biosensors. First, sensing mechanisms and principles of olfaction and gustation are briefly introduced. Then, different biomimetic sensing detection strategies are outlined based on different sensing devices functionalized with various molecular and cellular components originating from natural olfactory and gustatory systems. Thereafter, various biomimetic olfactory and gustatory biosensors are introduced in detail by classifying and summarizing the detection strategies based on different sensing devices. Finally, the future directions and challenges of biomimetic biosensing development are proposed and discussed.