Parameters necessary to define an immobilized enzyme preparation

Chitin and its N-deacetylated derivative chitosan are two biological polymers that have found numerous applications in recent years, but their further deployment suffers from limitations in obtaining a defined structure of the polymers using traditional conversion methods. The disadvantages of the currently used industrial methods of chitosan manufacturing and the increasing demand for a broad range of novel chitosan oligosaccharides (COS) with a fully defined architecture increase interest in chitin and chitosan-modifying enzymes. Enzymes such as chitinases, chitosanases, chitin deacetylases, and recently discovered lytic polysaccharide monooxygenases had attracted considerable interest in recent years. These proteins are already useful tools toward the biotechnological transformation of chitin into chitosan and chitooligosaccharides, especially when a controlled non-degradative and well-defined process is required. This review describes traditional and novel enzymatic methods of modification of chitin and its derivatives. Recent advances in chitin processing, discovery of increasing number of new, well-characterized enzymes and development of genetic engineering methods result in rapid expansion of the field. Enzymatic modification of chitin and chitosan may soon become competitive to conventional conversion methods.

/pdf/enzymatic-modifications-of-chitin-chitosan-and-1dpl5yo3fv.pdf

Enzymatic Modifications of Chitin, Chitosan, and Chitooligosaccharides.

Fermented foods have long been produced according to knowledge passed down from generation to generation and with no understanding of the potential role of the microorganism(s) involved in the process. However, the scientific and technological revolution in Western countries made fermentation turn from a household to a controlled process suitable for industrial scale production systems intended for the mass marketplace. The aim of this paper is to provide an up-to-date review of the latest studies which investigated the health-promoting components forming upon fermentation of the main food matrices, in order to contribute to understanding their important role in healthy diets and relevance in national dietary recommendations worldwide. Formation of antioxidant, bioactive, anti-hypertensive, anti-diabetic, and FODMAP-reducing components in fermented foods are mainly presented and discussed. Fermentation was found to increase antioxidant activity of milks, cereals, fruit and vegetables, meat and fish. Anti-hypertensive peptides are detected in fermented milk and cereals. Changes in vitamin content are mainly observed in fermented milk and fruits. Fermented milk and fruit juice were found to have probiotic activity. Other effects such as anti-diabetic properties, FODMAP reduction, and changes in fatty acid profile are peculiar of specific food categories.

Health-Promoting Components in Fermented Foods: An Up-to-Date Systematic Review.

The primary intention of this review is to showcase and quantify the level of research interest and current research trends concerning UF membrane applications and processes within the past decade (2009–2018). Detected statistics revealed a resurgent interest in the UF technology on a yearly basis. "Journal of Membrane Science" and "Desalination and Water Treatment" were the primary journals dominating the size of the annual publication output among more than 120 journals, with 854 and 683 papers, respectively. Based on the ScienceDirect research platform, fouling (27 %), modelling (17 %) and wastewater (12 %) were the dominant research topics and accounted for more than half of the total scientific articles published (4547 articles) within the specified period of the research. Unsurprisingly, topics like UF membrane fabrication and modification, food processing, and hybrid membrane process have revealed a growing trend in terms of annual publications. The current review revealed the present-day significance of UF membranes along with their prospective opportunities for attaining sustainability in water industries and materializing the efforts of future researchers in the right direction.

https://cronfa.swan.ac.uk/Record/cronfa53822/Download/53822__16871__c261762051704e6ca31daf8fee70c51b.pdf

Ultrafiltration membranes for wastewater and water process engineering: A comprehensive statistical review over the past decade

Chitosan and their derivatives: Antibiofilm drugs against pathogenic bacteria.

Expression and characterization of a novel cold-adapted chitosanase suitable for chitooligosaccharides controllable preparation

Fermented vegetable–fruit beverages are a popular fermented food, with many potential health benefits. In this study, two commercial Lactobacillus plantarum strains were selected to ferment a beverage containing apples, pears, and carrots. The metabolites and antioxidant activities were examined during the fermentation process. Results showed that lactic acid and acetic acid accumulated gradually, whereas malic acid decreased. Glucose and fructose increased from 0.48 and 14.8 g/L to 7.7 and 20.8 g/L, respectively, while sucrose decreased slightly. Ascorbic acid also increased continuously during the fermentation to 90.74 mg/100 mL. DPPH and ABTS radical scavenging activity and FRAP reached their maximum value after 4–8 days. The accumulation of TPC, TFC, and SOD reached their maximum value on the 8th day of fermentation. Our study revealed that the L. plantarum-fermented vegetable–fruit beverage showed significant antioxidant activity, which is helpful in evaluating the fermentation end-point and developing a high-quality fermented beverage.

/pdf/antioxidant-properties-of-a-vegetable-fruit-beverage-2j0sfwuv7t.pdf

Antioxidant properties of a vegetable–fruit beverage fermented with two Lactobacillus plantarum strains

Chitooligosaccharides are widely used in functional food, medicaments and agriculture. Controllable conversion of chitosan to chitooligosaccharides with desired degree of polymerization (DP) is of great value. Herein, a novel glycoside hydrolase family 46 chitosanase (BaCsn46A) was cloned and expressed from Bacillus amyloliquefaciens. BaCsn46A exhibited good enzymatic properties with high specific activity (1031.2 U/mg) under optimal hydrolysis conditions of pH 6.0 and 50 °C. BaCsn46A is an endo-type chitosanase, which could be utilized to yield abundant chitooligosaccharides. Furthermore, the preparation of high degree of polymerization chitooligosaccharides (DP 5–10) was investigated by BaCsn46A in an enzymatic reactor with a subsequent series of membranes. The maximum concentration of total chitooligosaccharides (DP 2–10) was 28.11 g/L (93.70% yield). The proportion of high degree of polymerization chitooligosaccharides (DP 5–10) occupied 56.17% (w/w) of total chitooligosaccharides. This study provided a cleaner production process for the controllable preparation of chitooligosaccharides with specific degree of polymerization.

Zhen Qin

Papers

Expression and characterization of a novel cold-adapted chitosanase suitable for chitooligosaccharides controllable preparation

Antioxidant properties of a vegetable–fruit beverage fermented with two Lactobacillus plantarum strains

Biochemical properties of a novel chitosanase from Bacillus amyloliquefaciens and its use in membrane reactor

Structural insights into the substrate specificity of two esterases from the thermophilic Rhizomucor miehei

The recognition mechanism of triple-helical β-1,3-glucan by a β-1,3-glucanase.