Spray-Drying Microencapsulation of Anthocyanins by Natural Biopolymers: A Review

There has been an increased interest in the development of food colorants from natural sources as alternatives to synthetic dyes because of both legislative actions and consumer concerns. Anthocyanins are of great interest for the food industry since they give a wide range of colors as well as nutraceutical activities. Nevertheless, due to their low stability to environmental conditions during processing and storage, introducing those compounds into foods is challenging. Microencapsulation may be an efficient way to introduce such compounds into those products. An important step in developing microcapsules is the selection of a biopolymer (wall material) which meets the required criteria. Hence, this review will focus on microencapsulation of anthocyanins with different biopolymers through spray drying to develop natural colorant pigments which possess high stability, solubility, and dispersibility. Our goal is to give updated information regarding microencapsulation of anthocyanins by spray drying, as well as its effectiveness, developments, and optimized conditions which will be discussed.     

LIPASES AND LIPASE-CATALYZED ESTERIFICATION REACTIONS IN NONAQUEOUS MEDIA

Enzymatic reactions in nonaqueous solvents offer new possibilities for the biotechnological production of many useful chemicals using reactions that are not feasible in aqueous media. In the recent years, the use of enzymes in nonaqueous media has found applications in organic synthesis, chiral synthesis or resolution, modification of fats and oils, synthesis of sugar-based polymers, etc. The use of lipases in esterification reactions to produce industrially important products such as emulsifiers, surfactants, wax esters, chiral molecules, biopolymers, modified fats and oils, structured lipids, and flavor esters is well documented. The interest in using lipases as biotechnological vectors for performing various reactions in both macro- and microaqueous systems has picked up tremendously during the last decade. This review covers important features of lipases and lipase-catalyzed esterification reactions including the kinetics and stability of lipases, and modeling aspects.     

The effect of naturally occurring biopolymers on polyamide membrane fouling during surface water treatment

Parallel experiments using a blend of surface waters were conducted to evaluate differential fouling rates among reverse osmosis (RO) membranes when operated under pilot- vs. full-scale conditions. Testing was conducted using a 230 L/min conventional (rapid mix/flocculation/sedimentation/filtration) package plant (CPP) and a 2,000 ML/d fullscale treatment plant (FTP) as pretreatment to separate RO membrane test units. Coagulation consisted of 10 mg/L alum (as Al₂(SO₄)₃-14H₂O) and 2.0 mg/L cationic polymer. A2.5-3.0 mg/L free-chlorine residual was maintained at the filter effluent and converted to chloramines through ammonium sulfate addition (3:1 chlorine-to-ammonia w/w ratio). Membrane performance was based on normalized flux and salt rejection data. Membrane surface analyses included scanning electron microscopy, energy-dispersive spectroscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. Microbial activity and community analyses were conducted through (a) fluorescence staining with 4′,6′-diamidino-2-phenylindole, (b) polymerase-chain reaction amplification of isolated bacterial DNA, and (c) microscopic taxonomic identification. Results indicated that the RO membrane fed by the CPP fouled at least three times faster than the RO membrane fed by the FTP. The differential fouling between the two process streams was determined to be from lack of maintenance in the CPP influent piping that led to the establishment of biological communities consisting of algae, microbes, and, potentially, freshwater clams. These communities produced low levels of natural polymers, which when presented to the polyamide RO membrane surface, resulted in rapid fouling.     

Current research on the blends of natural and synthetic polymers as new biomaterials: Review

This review reports recent advances in the field of the blends of natural and synthetic polymers as new biomaterials. These materials have attracted both academic, and, for several blends, industrial attention because they exhibit improvements in properties required in the biomedical field. Herein, the structure, preparation and properties of the blends of natural and man-made polymer are discussed in general, and detailed examples are also drawn from scientific literature and practical work. The most common natural polymers: collagen, chitosan, elastin, keratin and silk are discussed as a components of blends with man-made polymers.     

Hydrophilic plasticized biopolymers: Morphological influence on physical properties

Biopolymers such as amylose, when mixed with plasticizers have excellent potential in forming thin films for various food and packaging applications. In this study, the influences of moisture content, plasticizer type and content have been investigated on the physical tensile elongation and crystalline morphology of starch biopolymeric material. Biopolymeric samples prepared with starch and two types of plasticizer with different molecular weights, namely glycerol (M_wt = 92) and xylitol (M_wt = 152), were employed, which also have different numbers of hydroxyl (OH) groups (3 for glycerol and 5 for xylitol). A statistical design of experiments (DoE) was performed on the sample responses (i.e. tensile elongation and crystalline morphology) by varying the moisture content, plasticizer type as well as plasticizer content. Plasticizer type and degree of crystallinity have been found to be insignificantly related. However, the plasticizer content has shown a significant effect on both elongation and crystallinity. A clear B-type pattern (peak at 2θ = ∼ 20°) has been observed in most X-ray diffraction (XRD) results.     

Electrophoretic Deposition Behavior of Chitosan Biopolymer as a Function of Solvent Type

The influence of three different solvents including lactic acid, formic acid, and acetic acid on the constant-voltage electrodeposition behavior of chitosan biopolymer was investigated. In this regard, charge density, viscosity, and some molecular parameters of chitosan solutions in aqueous acids were studied. The mechanism of chitosan film formation was investigated by fitting the current density–time experimental data to the Pierce and Miskovic film growth models. It was found that solvents have a significant influence on the molecular structure and electrodeposition behavior of chitosan. Using formic acid as the solvent caused the best electrophoretic mobility and resulted in a less porous film compared to acetic acid and lactic acid.     

Opportunities for bio-based packaging technologies to improve the quality and safety of fresh and further processed muscle foods

It has been well documented that vacuum or modified atmosphere packaging materials, made from polyethylene- or other plastic-based materials, have been found to improve the stability and safety of raw or further processed muscle foods. However, recent research developments have demonstrated the feasibility, utilization, and commercial application of a variety of bio-based polymers or bio-polymers made from a variety of materials, including renewable/sustainable agricultural commodities, and applied to muscle foods. A variety of these bio-based materials have been shown to prevent moisture loss, drip, reduce lipid oxidation and improve flavor attributes, as well as enhancing the handling properties, color retention, and microbial stability of foods. With consumers demanding more environmentally friendly packaging and a desire for more natural products, bio-based films or bio-polymers will continue to play an important role in the food industry by improving the quality of many products, including fresh or further processed muscle foods.     

Physical aging of processed fragmented biopolymers

Low moistures foods containing starches exhibit a sub-T_g endotherm (55–60 °C) when they are stored at constant temperatures. Although the origin of the endotherm is still debatable, it has been attributed to the water–hydroxyl group interactions and/or enthalpic associations between water and carbohydrates. In the present study, physical aging of the starch components of corn flakes prepared with two different levels of starch fragmentation was studied using thermal and rheological methods. A sub-T_g endotherm was observed at temperatures around 50–60 °C by both DSC and Oscillatory Squeezing Flow measurements. An increase of 1.5% of moisture content was observed for both fragmented flakes during aging. The temperatures at which the sub-T_g endotherms occurred were independent of aging and moisture content increase during storage, whilst enthalpy increased with both aging time and moisture content. Although the moisture content of the two types of flakes were different the aging time at which the first endotherm appeared and the rate at which the enthalpy increased were dependent only on the level of starch fragmentation. Corn flakes with a high level of starch fragmentation required a longer period of aging time before the presence of the endotherm could be detected and had a greater rate of increase in enthalpy. Overall, flakes having higher starch fragmentation absorbed more water, and the percent of water uptake decreased with aging time. Flakes with low starch fragmentation exhibited little to no change in water uptake during aging.