Morphology, Mechanical, and Water Barrier Properties of Carboxymethyl Rice Starch Films: Sodium Hydroxide Effect

Carboxymethyl rice starch films were prepared from carboxymethyl rice starch (CMSr) treated with sodium hydroxide (NaOH) at 10–50% w/v. The objective of this research was to determine the effect of NaOH concentrations on morphology, mechanical properties, and water barrier properties of the CMSr films. The degree of substitution (DS) and morphology of native rice starch and CMSr powders were examined. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to investigate the chemical structure, crystallinity, and thermal properties of the CMSr films. As the NaOH concentrations increased, the DS of CMSr powders increased, which affected the morphology of CMSr powders; a polyhedral shape of the native rice starch was deformed. In addition, the increase in NaOH concentrations of the synthesis of CMSr resulted in an increase in water solubility, elongation at break, and water vapor permeability (WVP) of CMSr films. On the other hand, the water contact angle, melting temperature, and the tensile strength of the CMSr films decreased with increasing NaOH concentrations. However, the tensile strength of the CMSr films was relatively low. Therefore, such a property needs to be improved and the application of the developed films should be investigated in the future work.

BIODEGRADATION OF MANGO SEED STARCH FILMS IN SOIL

The typical petroleum-based plastics have triggered environmental problems. For this purpose, biodegradable polymers such as starch are often used to manufacture biodegradable plastics. At present, the efforts are underway to extract starch as a promising biopolymer from mango seeds and subsequently to produce a biodegradable starch film to be used as plastic packaging. As such, in this work, glycerol-plasticized mango starch films were prepared using a solution casting process, using different amounts of citric acid as a cross-linking agent. The blend ratio of starch to glycerol was set at 3:5 wt. each, while the amount of citric acid ranged from 0 to 10 wt.%. Then, the casted films underwent 21 days of soil burial testing in the natural environment to determine their biodegradability behavior. The soil burial test is one of the common methods chosen to assess the biodegradability of polymers. The idea is that, by burying samples in the soil for a fixed time, samples are exposed to microorganisms (i.e. bacteria and fungi) present in the soil that serve as their food source. This is somehow likely to facilitate the process of deterioration. For this reason, the soil burial test can be regarded as an authentic approach to the process of deterioration in the natural environment. The films' susceptibility to biodegradation reactions was assessed within intervals of seven days through their physical appearance and weight loss. Interestingly, it was found that the cross-linked starch films have been observed to degrade slower than the non-cross-linked starch films as burial time progressed. The declining percentages of weight loss, as well as the presence of microorganisms and eroded surface on the films observed by SEM, explained the degradation behavior of the cross-linked starch films compared to the non-cross-linked starch films. Hence it is believed that cross-linked starch-glycerol films are biodegradable in soil, henceforth, the potential to be commercialized as a biodegradable packaging material soon. At the same time, this plastic packaging is expected to be recognized as a value-added product since the raw materials ergo mango seeds utilized to develop this product are from waste, therefore, environmentally friendly. ABSTRAK: Plastik yang berasaskan petroleum telah mencetuskan masalah persekitaran. Untuk tujuan ini, polimer biodegradasi seperti kanji sering digunakan untuk membuat plastik yang boleh terurai. Pada masa ini, usaha sedang dilakukan untuk mengekstrak pati sebagai biopolimer yang menjanjikan dari biji mangga dan kemudiannya menghasilkan filem pati yang terbiodegradasi untuk digunakan sebagai kemasan plastik. Oleh yang demikian, dalam karya ini, filem pati mangga plastik-gliserol disusun menggunakan proses pemutus larutan, menggunakan jumlah asid sitrik yang berlainan sebagai agen penghubung silang. Nisbah campuran pati dan gliserol ditetapkan pada 3:5 wt.% masing-masing, sementara jumlah asid sitrik berkisar antara 0 hingga 10 wt.% berat. Kemudian, sampel plastik tersebut ditanam di dalam tanah selama 21 hari di persekitaran semula jadi untuk menentukan tingkah laku biodegradasinya. Ujian penguburan tanah adalah salah satu kaedah biasa yang dipilih untuk menilai biodegradasi polimer. Ideanya adalah bahawa, dengan menguburkan sampel di tanah untuk waktu yang tetap, sampel terdedah kepada mikroorganisma (iaitu bakteria dan jamur) yang terdapat di dalam tanah yang berfungsi sebagai sumber makanan mereka. Ini mungkin memudahkan proses kemerosotan. Atas sebab ini, ujian penguburan tanah dapat dianggap sebagai pendekatan yang sahih terhadap proses kemerosotan di persekitaran semula jadi. Kerentanan filem terhadap reaksi biodegradasi dinilai dalam selang waktu tujuh hari melalui penampilan fizikal dan penurunan berat badan. Menariknya, didapati bahawa filem-filem pati berangkai silang telah dilihat menurun lebih perlahan daripada filem-filem pati yang tidak bersilang ketika masa pengebumian berlangsung. Peratusan penurunan berat badan yang menurun, serta kehadiran mikroorganisma dan permukaan yang terhakis pada filem yang diperhatikan oleh SEM, menjelaskan tingkah laku degradasi filem pati berangkai silang berbanding dengan filem pati yang tidak bersilang. Oleh itu, dipercayai bahawa filem kanji-gliserol berangkai silang dapat terbiodegradasi di dalam tanah, dan seterusnya, potensi untuk dikomersialkan sebagai bahan pembungkusan yang boleh terurai tidak lama lagi. Pada masa yang sama, pembungkusan plastik ini diharapkan dapat diakui sebagai produk bernilai tambah kerana bahan mentah ergo mangga yang digunakan untuk mengembangkan produk ini adalah dari sisa, oleh itu, mesra alam.

Sustainable Bioactive Packaging Based on Thermoplastic Starch and Microalgae

This study combines the use of corn starch and Tetradesmus obliquus microalgae for the production of antioxidant starch films as flexible packaging material. Starch was plasticized with glycerol and blended with 1 w% polyallylamine chosen as an agent to modify the film physical properties. The addition of polyallylamine improved film water stability and water vapor transmission rate as well as mechanical stiffness and tenacity. The dried Tetradesmus obliquus microalgae, which showed an EC50 value of 2.8 mg/mg DPPH (2.2-Diphenyl-1-picrylhydrazyl radical), was then used as antioxidant filler. The addition of microalgae provided the films with good antioxidant activity, which increased with microalgae content increasing. To our knowledge, this is the first study reporting the development of sustainable bioactive packaging films composed of almost 100% starch, and follows the European union’s goals on plastics strategy concerning the promotion of bio-based, compostable plastics and the setting up of approaches to prevent food waste with a simple plastic packaging.

Preparation and Physicochemical Properties of Modified Corn Starch–Chitosan Biodegradable Films

Starch is a biopolymer with enormous potential for generating new biodegradable packages due to its easy availability and low cost. However, due to its weak functional properties, limitation of its interaction with some hydroxyl groups and evaluation of blends with other polymers are necessary in order to improve its performance. Glycerol-plasticized acetylated corn starch films were developed using the casting method, and the impact of incorporating chitosan (TPS:CH) in various proportions (75:25, 50:50, and 25:75 v/v) was studied in the present research. The effect of chitosan ratios on the physical, mechanical, water-vapor barrier, and thermal properties of the film was studied. Chitosan-protonated amino groups promoted the formation of intermolecular bonds, improving tensile strength, thermal stability, hydrophobicity, water adsorption capacity, and the gas barrier of starch films. The results show that the film composed of TPS25-CH75 proved to be the best barrier to water vapor; thus, these composite films are excellent choices for developing biodegradable packaging for the food industry.

Development and Characterization of Active Native and Cross-Linked Pearl Millet Starch-Based Film Loaded with Fenugreek Oil

In this study, cross-linked pearl millet starch and fenugreek oil was used to develop active starch edible films to overcome the limitations of native starch and to substitute artificial preservatives with natural one. The starch was cross-linked at three levels (1%, 3% and 5%) using sodium trimetaphosphate (STMP), and physicochemical properties were studied. Moreover, a comparative study was conducted among four samples of films prepared using native starch, cross-linked starch, and native and cross-linked starch loaded with fenugreek oil for physical, thermal, mechanical, morphological, and antibacterial properties. The solubility, swelling, and amylose content of native and modified starch varied from 11.25–12.75%, 12.91–15.10 g/g, and 8.97–16.55%, respectively. The values of these parameters were reduced as the concentration of STMP increased. Cross-linked starch films showed lower moisture, solubility, water vapor permeability(WVP), and elongation at break (EB) values while having higher thickness, opacity, thermal, and tensile strength values. The microscopic images of cross-linked starch films showed smooth surfaces and the absence of ridges, pores, and cracks. The films loaded with fenugreek oil showed different results; the moisture content, water solubility, and tensile strength were decreased while thickness, opacity, WVP, and EB were increased. The onset temperature and peak temperature were lower, while enthalpy of gelatinization was increased to a greater extent than films without oil. The addition of fenugreek oil to films showed a good inhibition area of 40.22% for native+oil films and 41.53% for cross-linked+oil films % against Escherichia coli. This study confirmed the successful utilization of fenugreek oil as a very effective antimicrobial agent in preparing edible films.

Potential utilization of glycerol as crosslinker in starch films for application in Regenerative Dentistry

Periodontal disease results in damage to dental insertion apparatus. Regenerative procedures are proposed to replace lost structures in the context of guided tissue regeneration (GTR), guided bone regeneration (GBR) techniques and frequently associate bone substitutes with physical barriers aiming at greater longevity and improvement of aesthetic pattern. This study evaluates the possibility of using glycerol as a starch films modifying agent, acting as a cross-linking agent, without compromising its plasticizing effect. Biodegradable cassava starch films were prepared incorporating glycerol at concentrations of 0, 15, 20, 30 and 40% aiming application at dental regenerative procedures. The characterization of films by microscopy (SEM), thermal analysis (DSC), spectroscopic (UV / Vis., FTIR, XRD), mechanical (Traction), and analysis of protein swelling, degradation and diffusion and physiological temperature) showed that the incorporation of glycerol in up to 20% attributed to the films a plasticizer character and in higher concentrations, conferred a greater interaction of glycerol (crosslinking) with the starch chains and a degradation time that allows the physical barrier in RTG and ROG. The films presented mechanical resistance, malleability and permissiveness to protein diffusion in the in vitro assays, which meet the current attributes that guide the use of these resources in biomaterials.