Effect Of Agar Research Articles

The effect of agar from the seaweed Gracilaria fisheri on properties of biodegradable starch foam

This work focuses on the potential of agar from the seaweed Gracilaria fisheri to modify the properties of starch foam. The effects of different ratios of glycerol and agar on the properties of starch foams were investigated. All formulations used in this study produced easy-to-handle, smooth, single-use foam trays with no visible cracks. The addition of agar slightly affected the off-white color of the foam but red and yellow color values significantly decreased with increments of agar content. As the agar content was increased, the foam became less dense. A foam produced at a glycerol:agar ratio of 3:7 exhibited the highest values of flexural stress at maximum load (3.23 MPa), modulus (194.46 MPa) and hardness (97.50), and the highest temperature at maximum weight loss (Tmax) (337 °C). Therefore, starch foam modified with agar from Gracilaria fisheri showed suitable physical, mechanical and thermal properties for food packaging, and could possibly be used in the place of expanded polystyrene (EPS) foam.

Effect of Agar on the Mechanical, Thermal, and Moisture Absorption Properties of Thermoplastic Sago Starch Composites.

Thermoplastic starch is a material that has the potential to be environmentally friendly and biodegradable. However, it has certain drawbacks concerning its mechanical performance and is sensitive to the presence of moisture. The current study assessed agar-containing thermoplastic sago starch (TPSS) properties at various loadings. Variable proportions of agar (5%, 10%, and 15% wt%) were used to produce TPSS by the hot-pressing method. Then, the samples were subjected to characterisation using scanning electron microscopy (SEM), mechanical analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and moisture absorption tests. The results demonstrated that adding agar to starch-based thermoplastic blends significantly improved their tensile, flexural, and impact properties. The samples' morphology showed that the fracture had become more erratic and uneven after adding agar. FT-IR revealed that intermolecular hydrogen bonds formed between TPSS and agar. Moreover, with an increase in agar content, TPSS's thermal stability was also increased. However, the moisture absorption values among the samples increased slightly as the amount of agar increased. Overall, the proposed TPSS/agar blend has the potential to be employed as biodegradable material due to its improved mechanical characteristics.

Effect of agar and alginate on growth performance and levels of leukocytes and erythrocytes of Tilapia Oreochromis niloticus

The use of immunostimulants is an effort to increase the immune system in fish. Agar and alginate are phycocoloid derived from seaweed which function as immunostimulants. Research data collection was carried out for 60 days at the Aquaculture and Toxicology Environmental Research Installation, Cibalagung - Bogor. The container used is an aquarium with a size of 60 × 40 × 50 cm, using an aeration system with a stocking density of 15 fish / aquarium. The fish used was tilapia Oreochromis niloticus with an initial weight of 4.36 ± 0.01 g. The research method used was a laboratory experimental using a completely randomized design (CRD) with three replications. The research treatment is the use of agar and or alginate in feed. Treatment A was control feed without agar or alginate; treatment B was feed containing alginate; Treatment C was feed containing agar and treatment D was feed containing agar and alginate, with 1% dose for each treatment. Parameters measured were absolute weight growth, specific growth rate, survival rate and blood profile (leukocytes and erythrocytes). The results showed that the addition of agar and or alginate to the feed did not have a significant effect on growth and survival, but had a different effect on the profile of white blood cells (leukocytes) compared to the control. Between alginate treatment (B), agar treatment (C) and agar + alginate treatment (D), agar treatment (C) showed the highest value in weight gain (10.437 ± 0.65 g), specific growth rate (3.06 ± 0.08% / day), and survival (100 ± 0.0%). Whereas for blood profile, treatment B had the highest leukocyte levels, namely 9.89 × 104 cells / mm3 and treatment C had the highest erythrocyte levels, namely 1.71 x106 cells / mm3. The conclusion of this study was that the addition of agar and/or alginate in feed did not affect the growth and survival of tilapia but was able to increase the number of fish leukocytes.

Mixed leather of açaí, banana, peanut, and guarana syrup: the effect of agar and gellan gum use on quality attributes

The aim of the present study was to develop a mixed leather of açaí, banana, peanut, and guaraná syrup with nutritional characteristics, high fiber content and energy value using hydrocolloids agar and gellan gum as a binding agent. For this purpose, different concentrations of these hydrocolloids were evaluated in the development of mixed leather. The following formulations were developed: agar (0.50%) and gellan gum (0.50%), as (A050/G050); agar (0.75%) and gellan gum (0.25%), as (A075/G025); and agar (1.0%), as (A1). The concentration of dietary fiber in the formulation containing 0.50% of agar demonstrated significant differences in comparison to the other samples (p < 0.05). The addition of 0.75% of agar presented a higher average for carbohydrates (56.85 mg 100/g). The most negative impact on the bioaccessibility of the total phenolic compounds (TPC) and antioxidant activity (ABTS and FRAP) was in the A050/G050 sample. Regarding rupture strength, the sample A1 showed the lowest value (2.42 N) among all of the mixed leathers. The drying process contributed to the shrinkage of the polymer network of agar and gellan gum, resulting in a more compact mixed leather. This polymer net, in turn, trapped the lipid content, as well as the TPC (after gastrointestinal digestion) of mixed leather A1, thus providing beneficial effects to the body. Finally, the addition of 1% of agar stood out for presenting greater results for these parameters, offering a viable alternative for the production of a more nutritious product.

Effect of agar and walnut (Juglans regia.L) shell fibre addition on thermal stability, water barrier, biodegradability and mechanical properties of corn starch composites

ABSTRACT Starch-based films plasticised with sorbitol and citric acids as cross-linking agents were synthesised by the solvent casting method with varying concentrations of agar. The films were characterised in terms of TGA, water barrier, tensile data and soil burial degradability testing. The increasing concentration of agar enhanced the thermal stability and degradability of the composites. At an optimum level of agar, the film showed the maximum tensile strength (17.84 ± 0.23) MPa which was further chosen to analyse the additional effect of walnut shell fibre (WSF). The film containing WSF showed a remarkable improvement in tensile strength (TS) up to 15% (29.43 ± 0.75) MPa. The analysis of variance (ANOVA) of the tensile data confirmed the significant differences in the mean tensile strength from one kind of polymer blend to another (p < 0.05). TGA results showed that there was a regular increase in onset degradation temperature (To) and a decrease in weight loss percentage (at To) of starch/agar composites with the addition of fibre. The blends were more resistive towards water absorption in comparison to virgin.

Effect of agar and gellan gum on structured guava (Psidium guajava L.): Rheological behavior and gastrointestinal digestion in vitro

Structured guava (SG) was produced by inducing gelation of guava pulp adding agar and gellan gum (GG). The rheological properties, as well as in vitro bioaccessibility of ascorbic acid (AA), total antioxidant activity (TAA) and total extractable polyphenols (TEP) were investigated. The results illustrated that the SG gel network made from agar and low acyl gellan (LAG) was completely developed at temperatures close to 20 °C. LA75/HA25 showed higher elastic behavior in time sweep. The AA analysis of the pulp and SG revealed that these compounds remained practically unchanged after gastrointestinal digestion in vitro (GID), with a higher bioaccessibility percentage. The average values of TAA and TEP of the structured products were close to those of the guava pulp, with no interference from the use of agar and GG. The Optimized Descriptive Profile showed that the hydrocolloid used influenced the sensory attributes of the SG, changing the texture and appearance.

EFFECT OF AGAR AND KAPPA-CARRAGEENAN ON THERMAL AND MECHANICAL PROPERTIES OF THERMO PLASTIC STARCH (TPS)

Effect of Agar and kappa-Carrageenan on Thermal and Mechanical Properties of Thermo Plastic Starch (TPS) Thermoplastic starch needs to be blend with other materials because of its limited properties. In order to gain the desired properties, the interaction between the added component (filler, plasticizer, second polymer, etc) must be concerned as it can affect the performances of the final product. Thermoplastic starch has been successfully made with mixing and compression molding with the addition of agar and kappa-carrageenan. The effect of the added material has been studied with FTIR, Tensile, DSC, and TGA to investigate their mechanical and thermal properties. The FTIR spectrum has shown the shifting around the methyl group (C-H), a carboxyl group (C-O), and a hydroxyl group (O-H). Thermal analysis results presented different patterns in melting and degradation behavior. The tensile strength value did not show significant improvement with the presence of agar and kappa-carrageenan. It is shown that the addition of agar and kappa-carrageenan affects thermal behavior but does not significantly impact the mechanical properties.

Effect of Agar as Electrolyte Additive on the Aluminum-Air Batteries

The performance of aluminum-air battery is improved by adding agar molecules to the electrolyte (4 M NaOH). A significant suppression of the parasitic self-corrosion reaction and the improvement of fuel efficiency were obtained. The fuel efficiency is elevated up to 35.95% and the corrosion inhibition efficiency increases up to 62.8%. The physisorption of the agar molecules on the aluminum surface improved the performance of aluminum-air battery. The adsorption of agar molecules on the aluminum surface was observed from the surface analysis with SEM, Freundlich adsorption isotherm and the adsorption energies from the computational simulations. Furthermore, the optimized structure model of agar molecules on the aluminum surface was proposed. To figure out the inhibition performance of agar molecules as an electrolyte additive for aluminum-air batteries, the experimental methods such as hydrogen evolution test, electrochemical tests, surface analysis and density functional theory (DFT) with computational simulations are used in this study.

Effect of Agar on Flexural, Impact, and Thermogravimetric Properties of Thermoplastic Sugar Palm Starch

Development of a new polymer from renewable resources is getting serious attention from researchers due to the environmental issue caused by petroleum based polymer. The aim of this paper is to study the behavior of sugar palm starch (SPS) based thermoplastic containing agar in the range from 10 to 40 wt%. The thermoplastics were melt-mixed and then hot pressed at 140 oC for 10 minutes followed by flexural, impact and thermogravimetric analysis. Thermogravimetric analysis (TGA) showed that incorporation of agar increased the char residue content from 9.17 to 10.87 wt%. For mechanical properties, the addition of agar improved the flexural strength and modulus of SPS/agar blends. The impact strength of thermoplastic SPS was increased respectively with the addition of agar. However, at higher agar content (30 wt% to 40 wt%), the impact strength was decreased which attributed to high rigidity of the material at this ratio. In conclusion, incorporation of agar has improved the flexural, impact and thermal properties of thermoplastic SPS which widened the potential application of this biopolymer in future. Keywords: Biopolymer, thermoplastic, agar, starch, sugar palm, flexural, impact, thermal.

Characterization of agar/soy protein biocomposite films: Effect of agar on the extruded pellets and compression moulded films

Agar/soy protein biocomposite films were successfully processed by extrusion and compression moulding, obtaining transparent and homogeneous films. The conformational changes occurred during the extrusion process and the effect of agar on the final properties were analyzed. As shown by differential scanning calorimetry (DSC) and specific mechanical energy (SME) values, during the extrusion process protein denatured and unfolded protein chains could interact with agar. These interactions were analyzed by Fourier transform infrared spectroscopy (FTIR) and the secondary structure was determined from the amide I band. Those interactions were supported by the decrease of film solubility. Furthermore, the good compatibility between agar and soy protein was confirmed by the images from scanning electron microscopy (SEM).

Growth and phytochemical levels in micropropagated Eucomis autumnalis subspecies autumnalis using different gelling agents, explant source, and plant growth regulators

The therapeutic value of Eucomis species is well recognized in African traditional medicine. As a potential approach to improve growth and phytochemical content in Eucomis autumnalis subspecies autumnalis, the effect of agar (Bacteriological Agar No. 1 Oxoid) and gellan gum (GELRITE™) was evaluated using different explant sources and plant growth regulator (PGR) combinations. After 10 wk, the growth parameters were measured and phytochemical levels in 50% methanol (MeOH) extracts of the dried regenerated plantlets were determined using colorimetric methods. The highest mean shoot number (ca. 9 per explant) was observed in gellan gum-solidified media using a benzyladenine (BA) and α-naphthaleneacetic acid (NAA) treatment. Regardless of the gelling agent or PGR applied, the (initial/primary) explant source (LDL = leaf explant derived from primary leaf regenerants and LDB = leaf explant derived from primary bulb regenerants) significantly influenced all the parameters with the exception of shoot length and number of bigger shoots (≥5 mm). In most cases, the regenerants from agar-solidified media contained higher levels of flavonoids and phenolics. In terms of PGRs, the BA + NAA treatment had the highest shoot proliferation (fourfold higher than PGR-free) and number of larger shoots in LDL (gellan gum) and LDB (agar and gellan gum) regenerants. Generally, the evaluated factors (gelling agent, explant source, and PGR) significantly affected the concentrations of all the phytochemicals with the exception of total phenolic content. Taken together, the current study justifies the need to fully evaluate the manner in which in vitro culture conditions/factors affect the overall outcome of micropropagation endeavors.

Self Disinfecting Reversible Hydrocolloid Impression Gels: Effect of Composition and Nanosilver on Characteristic Properties and Gelation Temperature

We have developed a new hydrocolloid impression gel to eliminate disinfection process that caused to inaccuracy in dimensions of final mold. At first, the proper sample has been prepared based on recommended formulation in literature as well as trial and errors via experimental works. Formulations prepared by variation amounts of ingredients and also samples prepared by adding nanosilver as an antibacterial agent. Characteristic properties such as tear strength, gel temperature, compressive strength and elastic recovery of prepared hydrocolloid impression gels have been evaluated. The effect of agar, potassium sulfate and di-sodiumtetraborate (Borax) on characteristic properties has been investigated. In addition, role of nanosilver as an antibacterial which can be eliminate disinfecting process, on final properties of gels has been evaluated this work presents the role of ingredient on properties of self disinfecting agar impression gel.

Effect of Agar and Cotton Fiber on Properties of Thermoplastic Waxy Rice Starch Composites

Biodegradable polymer from thermoplastic waxy rice starch (TPWRS) was prepared by internal mixer and compression molding. Since tensile properties and water uptake of the TPWRS was still the main disadvantages, the TPWRS sample was, therefore, modified by agar and/or cotton fibers. The effect of different ratios of agar:cotton fibers on properties of the TPWRS matrix were also studied. It was found that new hydrogen bonds could be found for the TPWRS matrix with the addition of different ratios of agar: cotton fibers by the detection of IR peak shift. Tensile properties of the TPWRS sample were significantly improved by the addition of agar or cotton fibers and the highest tensile properties were obtained from the TPWRS composite modified with 4:6 agar:cotton fibers. In addition, thermal degradation temperature and thermal stability of the starch were improved by the incorporation of agar and/or cotton fibers. Moreover, color measurement, morphology, water uptake and biodegradability from soil burial test were also examined.

Mango pulp-agar based model gel: textural characterisation

The textural properties of a model gel system have been investigated by employing an experimental design concerning the effect of agar (1-3%), mango pulp (0-50%) and sugar (0-20%). A gel characterization method, based on the principle of penetration-shearing, has been applied to determine the response functions (fracture strain, fracture stress, energy for penetration-shearing and firmness). These textural indices can be fitted well (0.858 ≤ r ≤ 0.953, p ≤ 0.01) to second order polynomials. Agar possesses the maximum effect and an increase in agar content markedly increases these indices while sugar imparts mostly a curvilinear effect; a failure strain as high as 33% has been achieved by increasing the agar content. The individual optimization (maximization), based on canonical analysis, on these indices indicates that agar content to be more than 2.8%. Gels with extensively varying textural properties can be achieved by changing the proportions of these ingredients.

Effect of agar on the microstructure and performance of potato starch film

Films made of agar and potato starch were elaborated and tested for a potential use as food packaging. Fourier-transform infrared spectroscopy (FT-IR) confirmed that starch and agar were compatible and inter-molecular hydrogen bonds existed between them. Scanning electron microscopy (SEM) of composite film with 15% content of agar showed a compact and homogeneous structure. X-ray diffraction (XRD) indicated the composite films were amorphous. At 50% relative humidity (RH), the addition of agar could enhance the tensile strength (TS) from 5.33 to 11.76 MPa. At high moisture environment (75% RH), the addition of agar could also enhance TS value from 0.84 to 3.36 MPa. Fortunately, the addition of 5% agar increased the elongation (E) from 32.5% to 58.33%. Water vapor permeability (WVP) decreased from 6.29 to 4.60 × 10 −10 g Pa −1 s −1 m −1. In conclusion, the addition of agar improved microstructure of starch film, and then meliorated mechanical properties and WVP at high moisture environment. It widened the application of potato starch film in food packaging films as expected.

Effect of agar, galactomannan and indole-butyric acid on in vitro rooting of the pear cultivar ‘Durondeau’ and apple rootstock cultivar ‘Marubakaido’

SummaryThe influence of partial substitution of agar by galactomannans in culture media supplemented with different concentrations of indole-3-butyric acid (IBA) was studied on in vitro rooting of pear (Pyrus communis L.) cultivar ‘Durondeau’ and apple rootstock (Malus prunifolia Borkh.) cultivar ‘Marubakaido’. The galactomannans applied were obtained from Cassia fastuosa (cassia) and Cyamopsis tetragonolobus (guar gum) seeds. The results obtained with mixtures of agar and galactomannan (3 g l–1 each) were compared with those from media solidified with a standard concentration of agar (6 g l–1). The rooting of pear shoots was enhanced significantly in the presence of a mixture of agar plus cassia galactomannan compared to medium solidified with agar only. The modified media promoted a higher number of roots than the control, and increased the percentage of rooted shoots. A maximum of 84.8% rooting was obtained on half-strength MS medium (1⁄2MS) supplemented with 0.49 µM IBA and solidified with a blend of agar plus cassia galactomannan. For the apple rootstock, only the number of roots per shoot was influenced significantly by the addition of galactomannan to the rooting medium. The highest number of roots per shoot was 16.67 on 1⁄2MS medium gelled with a mixture of agar plus guar galactomannan supplemented with 4.90 µM IBA. The behaviour of the agar-galactomannan gel and the possibility of reduced costs when compared with systems containing only agar, suggest new biological and commercial applications for galactomannans.

Effect of Gelling Agent on Growth and Development of Ceratozamia hildae Somatic Embryos

I. Abstract Individual somatic proembryos of Ceratozamia hildae were exposed to media that differed only in gelling agent utilized. Five different gelling agents were compared in the first experiment: Bacto agar, Agargel, Gel-Gro, Phytagar, and TC agar. In addition, the effect of agar was examined at two levels. Growth, proliferation, and development were assessed. The lower level of agar did not support good somatic proembryo growth. Agargel and the high agar concentration produced cultures with good proliferation. Proembryos exposed to Phytagar, Gel-Gro, and TC agar had the highest proliferation rates. Overall, Gel-Gro was considered the best gelling agent tested. The three concentrations of Gel-Gro used in the second experiment were 2, 4, and 6 g·l−1, with the lowest concentration representing the control, the recommended concentration. As gelling agent concentration increased, so did mortality; however, the highest Gel-Gro concentration also produced the highest numbers of good-quality, mature somatic...

Beneficial effect of agar for the frozen storage of bisected embryos

The effect of agar embedding on the viability of intact and bisected goat embryos during freezing and thawing was examined. Blastocysts or hatched blatocysts were bisected into haves by micromanipulation. After embedding with or without agar, they were stored by deep freezing. After thawing, undamaged and some partially damaged embryos were transferred into uteri of recipients. Of 22 demi-embryos embedded with agar, only one was undamaged, but of 58 demi-embryos embedded with agar, 29 were undamaged. Although one set of monozygotic twins was obtained after the transfer of 15 sets of frozen-thawed bisected embryos, the pregnancy rate (47%) and the proportion of young (27%) were lower than those obtained by transfer of frozen-thawed, intact embryos (67 to 80% for pregnancy rate, 45 to 53% for the young).

The Effect of Agar vs. Liquid Medium on Rooting in Tissue-cultured Sweetgum

Abstract It is increasingly evident that the concentration and type of matrix used in nutrient media can profoundly influence the response of tissues cultured in vitro. Picea abies shoot cultures exhibited increased dry weight yields (4) and increased shoot growth (9) with decreasing agar concentrations. Singha (5) compared shoot proliferation of crabapple and pear in Phytagar concentrations ranging from 0% to 1.2%. Optimal proliferation and growth occurred in crabapple on 0.3% agar, with higher concentrations decreasing these growth characteristics. In pear, increasing agar concentration also decreased shoot growth, but shoot proliferation was greatest at 0.6% or higher agar concentrations. Rooting has been promoted without or with lower agar concentrations in grape (1), Norway spruce (9), and apple (10). However, vitrification (glassiness or waterlogging) has been shown to increase with lower agar concentrations (9) and limits the use of liquid culture in some species.

Effect of thioglycolate on phagocytic and microbicidal activities of peritoneal macrophages.

Brewer thioglycolate-elicited mouse peritoneal macrophages were as active as resident peritoneal macrophages in the phagocytosis of opsonized Staphylococcus epidermidis but were unable to kill ingested microorganisms. This decreased functional activity was restricted to Brewer thioglycolate-elicited macrophages, since peritoneal macrophages elicited with NIH thioglycolate, alone or supplemented with agar and methylene blue, were as active as resident peritoneal macrophages. No effect of agar on the functional activities of macrophages was observed. A defective intracellular killing by peritoneal macrophages due to Brewer thioglycolate was seen only after an intraperitoneal injection with thioglycolate, not after in vitro incubation of resident macrophages with thioglycolate. The results of this study show that, depending on the kind of thioglycolate used, the functional characteristics of elicited macrophages may alter. However, none of the forms of thioglycolate investigated induced the recruitment of activated macrophages.