Islamic Azad University
Damghan Branch
Faculty of Agriculture
A Thesis Submitted in Partial Fulfillment of the Requirments For
the Degree of M.sc(Ph.D)in Food scienc and technology
Title
Investigation on Rheological Behaviour of Dually Modified Cassava Starch/k-Carrageenan as Gelatin Alternative in Pharmaceutical Hard Capsules
Supervisor:
Abdorreza Mohammadi Nafchi, PhD
November 2013
(در فایل دانلودی نام نویسنده موجود است)
تکه هایی از متن پایان نامه به عنوان نمونه :
(ممکن است هنگام انتقال از فایل اصلی به داخل سایت بعضی متون به هم بریزد یا بعضی نمادها و اشکال درج نشود ولی در فایل دانلودی همه چیز مرتب و کامل است)
Table of Contents
1.3 Objectives of the study. 5
Chapter 2: Literature Review.. 8
2.1 PHARMACEUTICAL CAPSULES. 9
2.1.1 Pharmaceutical hard capsules. 10
2.1.2 Manufacture of gelatin capsules. 11
2.1.3 Properties of gelatin capsules. 15
2.1.4 Alternatives to Gelatin. 17
2.2. POLYSACCHARIDES STUDY.. 20
2.2.1.1 Composition and primary structure of starch. 21
2.2.1.2 Morphology and ultra-structure of starch grains. 24
2.2.1.3 Semi-crystalline structure of starch grains. 27
2.2.1.4 Thermal transitions. 30
2.2.1.5 Starch modification. 35
2.2.2.1 Chemical Structure. 53
2.2.2.2 Conformation of κ-carrageenan. 54
2.2.2.3 Gelation of κ-carrageenan. 60
2.2.2.4 Thermoreversibility of gels and rheological properties. 61
2.3 POLYSACCHARIDE MIXTURES. 65
2.3.2 Thermodynamic Incompatibility. 66
2.3.3 Gels based on mixtures polysaccharides. 68
2.3.3.1 Rheological properties. 69
2.3.3.2 Rheology of blends of starch. 70
Chapter 3: Materials and Methods. 72
3.1.3 Acid hydrolyzed hydroxypropylated cassava starch. 73
3.2.1 Preparation of solutions. 74
3.2.1.2 Starch and κ-carrageenan solutions. 74
3.2.2 Rheological properties. 77
3.2.2.2 Viscoelastic properties. 78
Chapter 4: Results and Discussions. 79
4.1 Rheological behavior of gelatin. 80
4.1.1 Gelatin solution at 50 °C.. 80
4.1.3 Viscoelastic properties of gelatin gels at 20 °C.. 86
4.2 Rheological behavior of starch-κ-carrageenan blends. 90
4.2.1 Rheological behavior at 50 °C.. 90
4.2.1.1 Dually modified cassava starch (HHSS) 90
4.2.1.3 Dually modified cassava starch/κ-carrageenan blends. 96
4.2.2 Rheological behavior in sol-gel transitions (from 50 °C to 20 °C) 102
4.2.2.1 Influence of κ-carrageenan content 104
4.2.2.2 Influence of the different extents of starch hydrolysis. 106
4.2.3 Rheological properties of gels at 20 °C.. 107
4.2.3.1 κ-Carrageenan gels. 107
Chapter 5: Discussion and Conclusion. 113
5.1 Synergy and gel state. 114
5.1.1 Dually modified cassava starch and κ-carrageenan. 114
5.2 Comparison with gelatin. 120
5.2.1 Solution properties. 120
5.3 Conclusion and recommendation for future research. 123
List of Tables
Table 2. 1: Properties and applications of modified starches. 35
Table 3.1: Compositions of the starch- κ-carrageenan solution. 76
Table 4.3: Viscosity of κ-carrageenan in different concentrations. 95
List of Figures
Figure 1.1: Research flowchart 7
Figure 2. 1: Formation of hard gelatin capsules by dip molding. 12
Figure 2. 2: Position fingers dipping during passage through the drying ovens. 13
Figure 2. 3: Steps removing (a) trimming (b), and assembly of capsules (c). 14
Figure 2. 7: Structure of amylose. 22
Figure 2. 8: Structure of amylopectin. 23
Figure 2. 10: The different levels of grain starch. 25
Figure 2. 11: Organization of starch grains in “blocklets”. 27
Figure 2. 12: X-ray diffraction diagram for crystalline starch type A, B and C. 28
Figure 2. 14: Crystalline arrangement of double helices of amylose type A and B.. 30
Figure 2. 16: Hydroxypropylation reaction. 38
Figure 2. 19: Starch granules trapped in discharged pulp of cassava starch process. 49
Figure 2. 21: κ -Carrageenan gelation model, cation to promote gelation. (Morris et al., 1980) 60
Figure 2. 24: Phase diagram at 25 °C mixture of waxy hydroxypropyl starch/κ-carrageenan. 67
Figure 4.1: Newtonian behavior of gelatin at 50 °C and 20% concentration. 80
Abstract
With the goal of finding an alternative to gelatin in the processing of pharmaceutical capsules, the effects of k-carrageenans on dually modified cassava starch were investigated. While film forming and mechanical properties are important in all pharmaceutical capsules, solubility at high solid concentration and thermo-reversibility are important factors for hard capsule processing. Casava starches were modified first by hydrochloric acid (0.14 N for 6, 12, 18, and 24 h at 50 °C) and secondly by propylene oxide (10, 20, and 30% of solid for 24 h at 40°C).
To improve the gel setting property of the dually modified starch, dually modified cassava starches were combined with k-carrageenan (0.25, 0.5, 0.75, and, 1%). The concentration of the K+ ion in the composite mixture was adjusted appropriately to achieve the same sol-gel transition temperature. The rheological properties of the mixtures were measured and compared, with gelatin as the reference material. The solution viscosity, sol-gel transition, and mechanical properties of the films made from the mixtures at 50 °C were comparable to those of gelatin. The viscoelastic moduli (G’ and G”) for the gel mixtures were lower than those of gelatin. The composite gels had temperatures of gelation similar to that of gelatin. Both viscosity in solution and stiffness in gels could be adjusted using high levels of κ-carrageenan and was relatively independent of the molecular weight of the starch. These results illustrate that dually modified cassava starch in combination with k-carrageenan has properties similar to those of gelatin, thus these starches can be used in dip-molding processes, such as those used to make pharmaceutical hard capsules.
Chapter 1: Introduction
1.1 Background
The capsule is one of the formulations of the oldest pharmaceutical in history, known especially from the ancient Egyptians. In Europe, it was not until the nineteenth century that the first gelatin pharmaceutical capsule with the patent of Mr. Dublanc pharmacist and his student Mr. Mothes. Over the years, this invention has been so successful that the production of capsules has grown rapidly in many countries. This has led to many improvements including the invention of hard gelatin capsules in 1846 by Mr. Lehuby (Podczeck & Jones, 2004).
The development of pharmaceutical capsules, used for therapeutic purposes, originates in the keen interest shown by the numerous researches in pharmacology. This has greatly expanded the range of possible formulations using pharmaceutical capsules. Today, pharmaceutical capsules are mainly based on animal gelatin from porcine or bovine. Gelatin is an animal protein that is a traditional ingredient in many fields, including food. Gelation properties at temperatures close to room temperature and formation of homogeneous films, potable, gelatin as a choice for the manufacturing of pharmaceutical capsules.
However, the use of animal gelatin in the food and pharmaceutical industry is governed by regulations becoming more stringent. The precautionary principal applied, for example, the risk of transmission by animal gelatin; the bovine spongiform encephalopathy (BSE) has questioned its use. Even if today the rules on the origin of the gelatin are very strict and that gelatin is no longer a risk to health, development of alternative products of interest to pharmaceutical and food industries. The sources from which gelatin can also be problematic for ethical or religious populations. Many people around the world do not consume products made from pork (vegetarians, Hebrews, and Muslims) or beef base (vegetarian Hindus). It is therefore that the replacement of gelatin with other texturing agents of non-animal origin has been much research in recent years.
The most important properties that potable gelatin as capsule forming material are heat sealability of films for soft capsule processing and solubility in high concentration, film formability and thermo-reversibility for making hard capsules.
Starch as a plant based material is one of possible alternative for gelatin due to cost and accessibility. Native starches can form films, but the films have not heat sealability, also starches are non soluble biopolymer, and form non-reversible gels. So changes or supporting the structure likely improve the starch property to consider as gelatin replacement in some cases.
The proposed system is a mixture of starch and k-carrageenan. Starch would give the mixture of film-forming properties and solubility in aqueous and carrageenan bring its ability to gel. The selected starch has focused on the use of such modification(s) on starch that able it to dissolve at temperatures below 100 °C and form stable solutions at high concentrations (≈ 20-30%). The botanical origin of the cassava starch is due to its proper amylose content, which improves mechanical properties of films and availability of this starch in Southeast Asia. The gelling agent has been studied was κ-carrageenan/K+ for its ability to form thermo reversible gels and easily adjustable thermo-physical transition temperatures. The film-forming mixtures were prepared by casting method.
The main objective of this research project is to replace the gelatin with a composite cassava (tapioca) starch film for manufacturing of pharmaceutical capsules especially hard capsules. The idea for hard capsule processing is to develop a new system whose characteristics in the solution and solid state would be closer to existing formulations. The constraints imposed industrial development concentrated formulations (25-30%) prepared at temperatures below 100 °C capable of forming a gel by physical cooling and forming a film after drying.
تعداد صفحه : 146
قیمت :14700 تومان
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