Hydroxypropylation of pigeon pea (Cajanus cajan) starch: Preparation, functional characterizations and enzymatic digestibility

Abstract Hydroxypropyl starch derivatives were prepared from pigeon pea starch (NPPS) which is an unconventional starch source. Functional parameters and characterization of both native and modified starches were carried out. The starch granules appeared oval or elliptical in shape with sizes ranging from 7 to 40 μm in width and 10 − 30 μm in length. Hydroxypropylation did not alter the shape of the starch granules in a pronounced way. Generally, the x-ray diffractograms of native pigeon pea starch showed the "A" pattern. However, slight reductions in the diffraction intensity of starches after modification were observed. At all temperatures studied (30–90 °C), swelling and solubility of hydroxypropylated starches were higher than the NPPS. Progressive increases in swelling capacity and solubility were observed as the molar substitution (MS) increased among the hydroxypropylated starches. Hydroxypropylation reduced starch paste turbidity on storage. Also, studies showed that syneresis reduced after hydroxypropylation. In addition, syneresis reduced as the MS of the hydroxypropyl starches increased. The results indicate that pasting temperature and peak temperature reduced after modification but peak viscosity increased in hydroxypropylated starch derivatives compared with the native starch. Setback reduced in hydroxypropylated starches compared with the native starch. Enthalpy of gelatinization and percentage retrogradation reduced after hydroxypropylation and progressive reductions were observed as the MS increased among the starch derivatives. Hydroxypropylation increased enzymatic digestibility

Preparation and Characterisation of Hydroxypropylated Crosslinked Sago Starch for Application in Acidic, Frozen and Canned Foods

Hydroxypropylation and crosslinking were carried out to improve the quality of sago starch. The optimum conditions for preparation of hydroxypropylated crosslinked sago starch were found to be an initial reaction with 10-12% propylene oxide at 40°C for 24 hr using 40% (dsb) starch slurry containing 15% sodium sulphate at pH 10.5. This was followed by crosslinking using a mixture of 2% sodium trimetaphosphate (STMP) and 5% sodium tripolyphosphate (STPP). Through hydroxypropylation, it was found that there was a significant increase in molar substitution which will in turn induce the increase in crosslinking and this was seen from the marked increase in phosphorus content and degree of substitution. This was accompanied by a significant decrease in paste clarity, swelling power and solubility compared to that of the native starch. The hydroxypropylated crosslinked sago starch prepared also exhibited desirable properties in that it exhibited no viscosity breakdown, high acid resistance, high freeze-thaw stability and improved gel texture. The hydroxypropylated crosslinked sago starch (HPST) was prepared in a larger scale having molar substitution (MS) and degree substitution (DS) values in the range of 0.038 to 0.045 and 0.004 to 0.005, respectively. The properties of HPST in tenns of sediment volume, swelling power, solubility and paste clarity were IS.7S%m1, 16.7, 8.62% and S.18 %T6so, respectively. The MS value, phosphorus content, paste clarity, swelling power and syneresis after six :freeze-thaw cycles of HPST when compared to that of commercially available modified starches which are normally used or incorporated in acidic, :frozen and canned foods did not differ significantly. The pasting characteristic of HPST exhibited thin to thick viscosity which is. similar (P>0.05) to that of commercial hYdroxypropylated crosslinked tapioca starch (NAT 8). The acid stability, solubility and :freeze-thaw stability of both starches were also similar (P>0.05) but the swelling power of HPST was slightly lower (P<0.05) than that of NAT 8.The canning stability of HPST in tenns of textural and rheological aspects was very high either in neutral or acidic canning condition at IS psig (121°C) for 30 min. However, when sterilised longer than 40 min at 121°C, the HPST pastes (6% starch solid) experienced a significant decrease in viscosity and firmness. The HPST paste which consisted of 6% starch solid and 10% sucrose at pH 6.S exhibited rapid heat penetration. A sterilisation value (Fo) of 25.48 could be obtained from the sterilisation of HPST paste contained in a can size 300x305 at 121°C for 30 min

Preparation and Characterization of Hydroxypropylated Sago Starch

Sago starch was hydroxypropylated with propylene oxide at 40°C in an alkaline medium containing sodium sulphate. In this study, the level of propylene oxide (0-14%), sodium hydroxide (0-2%), sodium sulphate(0-30%), reaction time (8-24 hrs) and reaction temperature (20-50°C) were varied to produce various samples of hydroxypropylated sago starch. The molar substitution (MS), which is the amount of substitution that has occured during hydroxypropylation and the pasting properties were measured for each sample. Increase in the amount of propylene oxide, sodium sulphate and sodium hydroxide, reaction temperature and reaction time progressively increased the molar substitution of the modified peak viscosity and the hot paste viscosity. However, the gelatinization temperature, the consistency of the hot paste viscosity after holding at 95°C and the setback value was decreased. Highest molar substitution of 0.41 was observed at 1.5% sodium hydroxide at which the highest peak viscosity and breakdown with the lowest setback value was also observed. The peak viscosity, cold paste viscosity and breakdown was highest at 25% sodium sulphate concentration. The maximum level of hydroxypropylation was observed at 10% propylene oxide, 1.5% sodium hydroxide, 25 % sodium sulphate, at 24 hours reaction time and at 40°C. In another study, hydroxypropylated sago and corn starch were prepared by reaction with propylene oxide in an alkaline medium containing sodium sulphate at 40°C and its physicochemical characteristics were studied and compared with the native starches. Some of the physicochemical characteristics evaluated were : pasting properties, molar substitution, swelling power and solubility, water holding capacity, gel strength, sediment value, light transmittance, acid and heat stability, starch damage and freeze-thaw stability. In addition, the morphology of the starch granules were also observed.Hydroxypropylation increased the swelling power and solubility, water holding capacity and freeze-thaw stability of both starches. The swelling power of sago starch increased from 33.69 ± 3.92 % to 60.44 ± 2.72% when it was hydroxypropylated. As for com starch the swelling power increased three times higher from 8.67 ± 0.056 % for native com to 24.99 ± 1.039% for hydroxypropylated com. The water holding capacity of native sago was 11.00 ± 0.12% and it further increased to 17.23 ± 0.25% when it was hydroxypropylated. As described in the literature, it was found that hydroxypropylation increased the freeze-thaw stability of the sago and com starches. The gel strength of the starches decreased when it was hydroxypropylated and the values were 56.5 ± 2.12%, 11.5 ± 0.71%, 84.5 ± 2.12% and 46 ± 1.42% for native sago, hydroxypropylated sago, native com and hydroxypropylated com respectively. The percentage of starch damage was only 0.02% when sago starch was hydroxypropylated but for com the starch damage was 2.64% when it was hydroxypropylated. The sediment value of native sago (96.25 ± 1.0%), was the highest followed by hydroxypropylated sago starch (94.54 ±0.57%), hydroxypropylated com starch (67.17 ±0.57%) and native com starch (27.0 ± 2.6%) respectively. Both starches when hydroxypropylated showed no improvements in their acid and heat stability

Effects of Chemical and Enzymatic Modifications on Starch and Naringenin Complexation

Naringenin is a flavanone naturally present in grapefruit and tomato skin, which has been demonstrated to have health benefits. However, because of the low water solubility and bioavailability, naringenin applications are limited. Starch inclusion complexes have been shown to improve the solubility and bioavailability of poorly water soluble bioactive compounds. The present study aimed to prepare and characterize complexes of naringenin with starches, including potato starch and high amylose corn starch (Hylon VII), which were chemically (acetylation or hydroxypropylation) and enzymatically modified (debranched or debrahced/β-amylase treated). Soluble and insoluble complexes were recovered, and their physicochemical properties were characterized. The treatments did not affect overall recovery, but the introduction of acetyl and hydroxypropyl groups significantly increased the recovery of soluble complexes. Overall, acetylated starches exhibited greater complexation yields than hydroxypropylated counterparts; Hylon VII complexes comprised greater naringenin contents than potato starch complexes. The naringenin content generally was greater in insoluble complexes than in soluble complexes and increased when β-amylase treatment was incorporated. The X-ray diffraction patterns of both complexes revealed a mixture of amorphous and crystalline structure. FT-IR results confirmed the occurrence of molecular interaction between starch and naringenin in both complexes. Melting properties were significantly influenced by the type and degree of substitution. The present results demonstrate that the complexation of starch with naringenin can be improved by a combination of chemical and enzymatic modifications

PREPARATION AND CHARACTERIZATION OF HYDROXYPROPYL METHYLCELLULOSE PRODUCED FROM α-CELLULOSE BETUNG BAMBOO (DENDROCALAMUS ASPER) AND IT’S EVALUATION ON GEL FORMULATION

Objective: This study aim to obtain the optimum condition of preparation of hydroxypropyl methylcellulose (HPMC) produced from α-cellulose betung bamboo, physicochemical properties of HPMC powder and its characteristics in a gel formulation. Methods: HPMC of betung bamboo (HPMC BB) were optimized by central composite design (CCD) using three variables (sodium hydroxide concentration, dimethyl sulfate concentration, and temperature) and five levels (0,±1, and±α). The suggested optimum condition was subjected to further characterization. HPMC BB was characterized using Fourier transform infrared (FTIR) spectrometry, particle size analyzer (PSA), x-ray diffraction (XRD), scanning electron microscope (SEM) and compared to HPMC 60SH as the reference. Then, HPMC BB was used as a gelling agent in a gel formulation and the gel was evaluated, including appearance and homogeneity, pH, viscosity, and spreadability. Results: Optimum condition of preparation of HPMC BB was using sodium hydroxide 27.68% (w/v) and 1.26 ml dimethyl sulfate (based on 1 g α-cellulose) at 58.11 °C which resulted in molar substitution 0.21 and degree of substitution 2.09. The results showed that HPMC BB was a fine powder with yellowish-white color, odorless and tasteless, pH 7.02, residue on ignition 1.39%, methoxy groups content 28.56%, hydroxypropoxy groups content 7.09%, mean particle size 98.595 μm, loss on drying 3.62%, and moisture content 7.47%. Flow properties of HPMC BB classified in the fair category. The infrared spectrum and diffraction patterns were relatively similar to HPMC 60SH. The gel has a good homogeneity and spreadability and viscosity 142.5 mPa⋅s. pH 6.37. Conclusion: Based on the comparison to reference, HPMC BB showed relatively similar physicochemical and powder properties. However, HPMC BB is not recommended as a gelling agent in gel formulation because it has a low viscosity

CHARACTERIZATION OF HYDROXYPROPYL CELLULOSE PRODUCED FROM α-CELLULOSE BETUNG BAMBOO (DENDROCALAMUS ASPER) AND IT’S APPLICATION IN TABLET FORMULATION

Objective: This study aimed to obtain the physicochemical properties of hydroxypropyl cellulose (HPC) powder from α-cellulose Betung bamboo and its characteristics in tablet formulation. Methods: HPC was prepared by hydroxypropylation of α-cellulose using 25% (w/v) sodium hydroxide and 10 ml propylene oxide (based on 1 g α-cellulose) at 70 °C for 3 h. HPC of Betung bamboo (HPC BB) was characterized using fourier transform infrared (FTIR) spectrometry, particle size analyzer (PSA), x-ray diffraction (XRD), scanning electron microscope (SEM) and compared to HPC grade SL (HPC SL) as the reference. Then, HPC BB was used as a binder in tablet formulation by direct compression method and the resulted tablets were evaluated. The tablets evaluation including weight and size uniformity, hardness, friability and disintegration time. Results: The results showed HPC BB powder was yellowish white, odorless and tasteless, pH 7.49, residue on ignition 0.68%, hydroxypropoxy groups content 54.75%, average particle size 37.39 μm, loss on drying 1.09%, and moisture content 3.34%. Flow properties of powder fulfilled the requirements based on literature. Infrared spectrum and diffraction pattern of HPC BB were relatively similar to HPC SL. The tablets have average weight 403.495 mg, diameter 12.16 mm, thickness 3.11 mm, hardness 4.11 KPa, friability 2.04% and disintegration time 24.88 s. Conclusion: Based on the comparison of powder characteristics and tablets evaluation, HPC BB has a great potential in tablet formulation which showed similar characteristics to reference

Derivatisation of Polyphenols

Polyphenols, such as tannins, offer potential as a bio-derived chemical feedstock. Their present utilisation is limited mainly to leather tanning and wood panel adhesives. However, appropriate derivatisation may alter both the chemical and physical properties and thereby allow further utilisation of polyphenols. Derivatisation of polyphenols was achieved by esterification and etherification of the phenol groups. Esterification was achieved by alcoholysis of acid chlorides and transesterification with vinyl esters, while etherification was achieved by the ring opening of propylene oxide. The polyphenols used were resorcinol, catechin, Pinus radiata bark tannin, and Schinopsis lorentzii tannin. The products were characterised using a range of techniques including NMR (1H, 13C and 2D NMR in both the solution and solid state), ESI-MS, GPC, DSC, TGA, and rheology. The preparation of polyphenolic esters by alcoholysis provided model compounds to establish the key chemical, spectroscopic, and physical features. A range of simple polyphenol esters such as resorcinol dilaurate and catechin pentalaurate were prepared using lauroyl chloride. Furthermore, tannin lauroyl esters were prepared with varying degrees of substitution. A transesterification method was developed for the preparation of polyphenol esters. Ester interchange occurred effectively in the presence of base catalyst in aqueous solution or dimethyl sulfoxide with short or long chain vinyl esters. This included the first report of the base-catalysed transesterification of flavonoids by vinyl esters to give products such as catechin mono- and di-laurate. Transesterification occurred preferentially at the B-ring as shown by NMR spectroscopy. Subsequently, this transesterification procedure was used to prepare tannin esters. The chemical and physical properties of polyphenol esters were assessed using thermal, antioxidant, and UV/VIS light absorption analysis. Thermal analysis indicated melt/flow properties for some of the polyphenol esters. In some cases, the thermal stability was also shown to increase upon esterification. The antioxidant activity was shown to decrease upon transesterification of pine bark tannin with vinyl laurate, while the UV/VIS absorption was shown to increase. These properties may lend the products towards applications as polymer additives or pharmaceuticals. Polyphenol ethers were prepared by the Williamson ether synthesis and ring opening of propylene oxide. However, the Williamson ether synthesis, a common route to prepare ethers, proved unsuitable for flavonoids. Catechin and tannin hydroxypropyl ether derivatives of varying substitution were prepared by the ring-opening of propylene oxide in the presence of triethylamine. Upon hydroxypropylation the thermal properties of the polyphenol were altered. For example, catechin hydroxypropyl ethers showed a glass transition, which was dependent upon the molar substitution, while rheology showed melt behaviour for several of the tannin hydroxypropyl ethers

Dual modification of starch via partial enzymatic hydrolysis in the granular state and subsequent hydroxypropylation.

The effect of enzymatic pretreatment on the degree of corn and mung bean starch derivatization by propylene oxide was investigated. The starch was enzymatically treated in the granular state with a mixture of fungal alpha-amylase and glucoamylase at 35 degrees C for 16 h and then chemically modified to produce enzyme-hydrolyzed-hydroxypropyl (HP) starch. Partial enzyme hydrolysis of starch in the granular state appeared to enhance the subsequent hydroxypropylation, as judged from the significant increase in the molar substitution. A variable degree of granule modification was obtained after enzyme hydrolysis, and one of the determinants of the modification degree appeared to be the presence of natural pores in the granules. Enzyme-hydrolyzed-HP starch exhibited significantly different functional properties compared to hydroxypropyl starch prepared from untreated (native) starch. It is evident that the dual modification of starch using this approach provides a range of functional properties that can be customized for specific applications

Preparation of Hydroxypropyl Chitosan

In order to solve poor water solubility of chitosan, chitosan was modified by C6 hydroxyl group. Hydroxypropyl chitosan with good water solubility was prepared by using chitosan as raw material, propylene oxide as etherifying agent and isopropanol as solvent in alkaline environment. The suitable conditions for etherification reaction were determined by single factor experiments. The results showed that the optimum conditions for the synthesis of hydroxypropyl chitosan were as follows: under the alkaline environment of 25℃, the amount of isopropanol was 25 g, the amount of propylene oxide was 25 g, the amount of chitosan was 2 g, the reaction time was 7 h, the yield of hydroxypropyl chitosan was 25.65%, and the grafting ratio was 68.81%