Gelling agents

Characterization of oral drug absorption from jelly formulations: effects of membrane permeability and intestinal fluid volume

This study aims to clarify the process of oral drug absorption from jelly formulations. Agar and pectin-based jellies containing drugs with different membrane permeability (high: antipyrine [ANT], medium: metoprolol [MET], low: atenolol [ATE]) were prepared and tested for in vitro drug release and in vivo drug absorption in rats. All drugs showed similar release profiles in vitro from both jelly formulations, except for the faster release from pectin jelly at neutral pH. In contrast, in vivo absorption of ATE but not of ANT from jelly formulations was significantly lower than from solution. Absorption of ATE and MET was low from agar jelly after oral administration, whereas additional water intake significantly increased the absorption. The process of drug absorption was described by the compartmental model consisting of jelly, intestinal fluid, and blood compartments. Drugs in the jelly diffuse into the intestinal fluid and then permeate the intestinal membrane. By considering the rate-limiting process, membrane permeability-dependent drug absorption from agar jelly and the effects of water intake were identified. In conclusion, jelly formulations may potentially decrease and delay drug oral absorption, especially of poorly permeable drugs. Intestinal fluid volume is one of the important factors to control the drug absorption.

Beyond carrots: Evaluation of gelling agents as wet feeds for Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae

Previous studies have shown that larvae of the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), need a source of moisture to grow and perform well. Currently, much research has been oriented towards the effect of dry feed on larval growth and performance. The effect of different wet feeds as moisture source on the performance traits of T. molitor larvae has not been thoroughly investigated yet. This study aims to investigate in laboratory trials the effect of various gelling agents (agar, carrageenans, guar gum, xanthan gum, sodium alginate, modified starch, and pectin) on the growth and performance of T. molitor larvae. A number of 50 newly emerged larvae obtained from the rearings of the LEAZ were inserted in plastic vials together with 4 g of wheat bran as dry feed. Additionally, 1 g of gelling agents was provided 3 times per week as moisture sources. Carrot slices served as control. Larval survival and weight were recorded weekly until the appearance of the first pupa. Dry feed was replenished when depleted. Our data showed that gelling agents efficiently supported the growth of T. molitor larvae, in terms of larval survival and weight, as well as feed utilization expressed as FCR. Interestingly, carrageenans seem to be the most appropriate gelling agent for T. molitor larvae rearing as it can enhance their weight and is also able to reduce their development time and their specific growth rate.

A Review on Hydrophobically Associated Alginates: Approaches and Applications

Alginates are linear anionic polysaccharides, which are well-known for their biocompatible, nontoxic, and biodegradable nature. The polymer consists of alternating units of β-(1 → 4)-linked D-mannuronic acid (M) and α-(1 → 4)-linked L-guluronic acid (G) that have hydroxyl and carboxyl groups as the main functional groups. As a large number of free carboxyl and hydroxyl groups are present in the polymeric chain, the polymer is predominantly hydrophilic. The food and pharmaceutical industries have been the most extensive utilizers of alginates to produce gelling and thickening agents. However, by imparting hydrophobicity to alginates, the range of applications can be widened. Although there are reviews on alginate and its chemical modifications, reviews focusing on hydrophobically associated alginates have not been presented. The commonly used chemical modifications to incorporate hydrophobicity include esterification, Ugi reaction, reductive amination, and graft copolymerization. The hydrophobically modified alginates play an important role in delivery of hydrophobic drugs and pesticides as the modification increases the affinity toward hydrophobic components and helps in their sustained release. Due to their nontoxic and edible nature, they find use in the food industry as emulsion stabilizer to stabilize oil-in-water emulsions and to improve creaming ability. Further, alginate-based materials such as membranes, aerogels, and films are hydrophobically modified to improve their functionality and applicability to water treatment and food packaging. This Review aims to highlight the important chemical modifications and methods that are done to impart hydrophobicity to alginate, and the applications of hydrophobically modified alginates in different sectors ranging from drug delivery to food packaging are discussed.

Quantitative and qualitative saccharide analysis of North Atlantic brown seaweed by gas chromatography/mass spectrometry and infrared spectroscopy

Brown seaweeds contain a variety of saccharides which have potential industrial uses. The most abundant polysaccharide in brown seaweed is typically alginate, consisting of mannuronic (M) and guluronic acid (G). The ratio of these residues fundamentally determines the physicochemical properties of alginate. In the present study, gas chromatography/mass spectrometry (GC/MS) was used to give a detailed breakdown of the monosaccharide species in North Atlantic brown seaweeds. The anthrone method was used for determination of crystalline cellulose. The experimental data was used to calibrate multivariate prediction models for estimation of total carbohydrates, crystalline cellulose, total alginate and alginate M/G ratio directly in dried, brown seaweed using three types of infrared spectroscopy, using relative error (RE) as a measure of predictive accuracy. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) performed well for the estimation of total alginate (RE = 0.12, R2 = 0.82), and attenuated total reflectance (ATR) showed good prediction of M/G ratio (RE = 0.14, R2 = 0.86). Both DRIFTS, ATR and near infrared (NIR) were unable to predict crystalline cellulose and only DRIFTS performed better in determining total carbohydrates. Multivariate spectral analysis is a promising method for easy and rapid characterization of alginate and M/G ratio in seaweed.

Desamerization of Bitter Jam: Biochemical and Sensory Quality

This work consists of studying the influence of the desamerization of the mesocarpe on the chemical composition and the sensorial quality of the jam, based on the bitter orange. The results of the various analysis show that desamerization decreases acidity, sugars, protein, and bioactive compound levels (carotenoids, polyphenols, and vitamin C), but desamerized jams still remain an important source of antioxidant compounds with antioxidant potential in the diet. Concerning the sensory analysis of the jams, the results show that the jam desamerized with water presents the same bitterness as the bitter jam and that the salt significantly reduces the bitterness of the jams.

Hydrocolloids as thickening and gelling agents in food: a critical review

Hydrocolloids are widely used in many food formulations to improve quality attributes and shelf-life. The two main uses are as thickening and gelling agents. As thickening agents, they find uses in soups, gravies, salad dressings, sauces and toppings while as gelling agents, they are extensively used in products like jam, jelly, marmalade, restructured foods and low sugar/calorie gels. The role of specific hydrocolloids for thickening and for gel formation is reviewed pinpointing specific applications in food formulations and for product development.

Kinetics of Gelation and Thermal Sensitivity of N-Isobutyryl Chitosan Hydrogels

N-Acylation of chitosan with carboxylic anhydrides in dilute acetic acid/methanol has been a well documented strategy to selectively modify chitosan. Although this reaction is known to lead to irreversible gel formation, the kinetics and mechanism of this process have not so far been addressed. To this purpose, gel formation during the N-isobutyrylation of chitosan was investigated as a function of the reaction stoichiometry (R), chitosan concentration, and temperature by small deformation oscillatory rheology. Gel formation follows closely the chemical reaction and it proceeds predominantly under second-order kinetics as established from the dependence of critical gel time, t(gel), on R and concentration. The activation energy value derived from t(gel) vs 1/T data (E(a) = 68.29 +/- 1.80 kJ/mol) was almost identical to values reported for the chitosan N-acetylation reaction in previous studies. An excess isobutyric anhydride is suggested to be necessary for nucleation and hydrophobic association. The potential application of N-isobutyrylchitosan (NIBC) hydrogels in the design of thermally sensitive materials is also demonstrated.

Physicochemical properties of cissus gum powder extracted with the aid of edible starches

Gum powder was extracted from the stem and root of the cissus (Cissus populnea Guill and perr Ampelidacae) plant using water. Extraction was facilitated by the incorporation of 25-50% edible starches of sweet cassava, sweet potato, and maize. Dry samples were milled and sieved through a 250-microm sieve. Proximate and physicochemical properties of the gum samples were determined using standard methods. Results of the proximate analyses showed that protein and ash contents of the root gum were appreciably higher than those of the stem gum. Values of the crude fiber and ether extract of the root gum were lower than those of the stem gum. Inclusion of edible starches in the extraction process appreciably lowered proximate values. Results of the physicochemical properties showed that cissus gum samples did not form true gel but a "putty-like" mass. Addition of starches at various levels did not alter the characteristic putty-like nature of the gum. The gum samples had a remarkably low oil absorption capacity. Cissus gum samples had appreciably higher emulsion capacity and stability than the samples containing starch. The pH of the cissus gum powder and those of the starch-containing samples lie in the low-acid range (5.69-6.49). Cissus gum samples were highly hygroscopic; however, the addition of starch lowered the hygroscopicity. Incorporation of 25% starch into cissus mucilage enhanced extraction of the gum without adverse alteration of the physicochemical properties.

Carrageenans and their use in meat products

Carrageenans are sulfated linear polysaccharides of D-galactose and 3,6-anhydro-D-galactose extracted from red seaweeds. They have been used by the food industry for their gelling, thickening, and stabilizing properties, and more recently by the meat industry for reduced fat products. Meat is a complex system of muscle tissue, connective tissue, fat, and water; during processing, numerous interactions occur among all these components. These interactions are responsible for the functional properties of the meat system. In meat products, carrageenans contribute to gel formation and water retention. Their addition is of special interest in low-fat meat products because fat reduction often leads to unacceptable, tough textures. When carrageenans are incorporated in these formulations, they improve the textural characteristics of the product by decreasing toughness and increasing juiciness. Although carrageenan interactions with milk proteins have been studied extensively, the mechanism by which carrageenans interact with meat proteins and the other meat components is not fully understood.

Mechanisms of meat batter stabilization: a review

Comminuted meat products are a complex mixture of muscle tissue, solubilized proteins, fat, salt, and water. The two theories that have been presented to explain meat batters stabilization are reviewed. The emulsion theory explains stabilization by the formation of a protein film around fat globules, whereas the physical entrapment theory emphasizes the role of the protein matrix in holding the fat in place during chopping and subsequent heating. However, some aspects of stabilization cannot be explained adequately by either one of these theories. In this article the role of meat proteins, aqueous phase, and lipid phase are examined in light of past and recent research findings.