Search

Pectin has the potential to be used as food packaging materials based on its natural properties such as mechanical strength and barrier properties. Due to the sustainable, non-toxic and biodegradable characteristics of pectin, many research have been focused on the development of pectin films and improvement of their properties by adding plasticizers, crosslinking agents and active compounds. In this study, the effect of glycerol and green tea extract (GTE) concentrations on the mechanical, morphologies, barrier and antioxidant properties of pectin films were investigated. The effect of different concentrations of glycerol (0, 10, 20, 30, and 40% w/w of pectin) on the thicknesses, mechanical strengths, storage/loss moduli, glass transition temperatures (Tg), chemical structures, crystallinity structures, moisture contents and gas permeabilities of low methoxyl pectin films enriched with 1% CaCl2 (w/w of pectin) were investigated and reported in Chapter 2. The mechanical strength of the films was tested from the results of tensile testing. The thicknesses, percent elongations and moisture contents increased with increasing concentrations of glycerol in the pectin films, whereas the tensile strength, Tg, and elastic and storage moduli increased with increasing glycerol contents. The FTIR results showed increasing ester and hydrogen bond formations with increased concentrations of glycerol in the pectin. The XRD results revealed that the crystallinity of the films decreased as a result of increasing glycerol concentrations, while the oxygen and water vapor barrier properties decreased due to the higher concentrations of glycerol. These results showed that glycerol can be used for the relaxation of the polymeric chains of pectin while reducing its tensile strength, stiffness and gas barrier properties.The effects of green tea extract (GTE) concentrations (0, 1, 2, 3, 4 and 5% w/w of pectin) on the thicknesses, mechanical strength, storage/loss moduli, glass transition temperatures (Tg), chemical structures, crystalline structures, antioxidant activities, moisture contents and gas permeabilities of low methoxyl pectin films with 30% glycerol (w/w of pectin) as plasticizer, and 1% CaCl2 (w/w of pectin) as crosslinking agent were investigated in Chapter 3 and same test methods were used. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assays were performed to test the antioxidant activities of the films. As a result, a decrease in the percent elongation and moisture contents accompanied with an increase in the tensile strength, Tg and elastic and storage moduli were observed with increasing concentrations of GTE in the pectin films. The thicknesses of the pectin films were not significantly affected by the concentrations of GTE. The FTIR results showed increasing ester bond formations with the increased concentrations of GTE in the pectin and an increase in H-bonding from 0 to 2%. When the GTE concentration increased from 2 to 5%, there was an increase in ester, but a decrease in the H-bonding. The XRD results showed that the crystallinity of the films increased as a result of increasing GTE contents. The results for the antioxidant activities and oxygen and water vapor barrier properties increased due to the higher concentrations of GTE. Therefore, low methoxyl pectin films incorporated with GTE have the potential to work as active packaging, with a significant change in desirable mechanical, morphological and barrier properties.

Edible films and coatings are increasingly being used as carriers of functional additives including antimicrobial agents. Consumer interest in naturally-derived antimicrobials has also increased. Plant extracts such as grape seed and green tea extracts are known to have antiviral as well as antibacterial activities. Even though there are several researches that have investigated the use of edible films and coatings as carriers of antimicrobial agents against foodborne bacterial pathogens, unfortunately data is lacking on the use of these same technologies on foodborne viruses. Therefore, this study seeks to develop edible films and coatings that can control foodborne viruses. The film’s antibacterial and mechanical properties were also tested. Chapters 1 and 2 introduce and review previous researches in edible films and coatings. Topics such as the types of biopolymer, film formation methods and mechanisms, foodborne viruses and bacteria, as well as edible film characterization and properties are discussed.Chapter 3 of this study investigated the virucidal activity of green tea extract (GTE) dissolved in deionized water and also incorporated into chitosan film forming solutions (FFS) and into chitosan films. For comparison, the antibacterial activity of the films was also investigated against Listeria innocua and Escherichia coli K12. The viral infectivity after treatments was measured by plaque assays. The 1, 1.5 and 2.5% aqueous GTE solutions significantly (p

Edible packaging (coatings and films) has been used to improve the shelf life, sensory attributes and nutritional content of food products. The manufacturing process for edible packaging depends on the properties of the ingredients and the application end use. The objective of this study was to optimize the method for commercial-scale chitosan film production. This was done by optimizing the raw ingredient selection, and blending sequence. Quality control tests were used to monitor these include viscosity, the drying rate of the ingredient slurries, film solubility, chemical compositions, as well as the thermal properties of the edible films made during the study. The first part of this dissertation (Chapter 2) focuses on the effects of solvents on the film properties. Edible slurries were prepared by dissolving 1.0-2.0% chitosan in 1.0% food-grade acetic or lactic acids with 0-20% ethanol solutions. Viscosities of the different film formulations were measured using a viscometer, and changes in drying time were determined using a OHAUS Moisture Determination Balance. Solubility of the films was determined by dissolving the dried films in water then measuring the weight changes. The chemical compositions of the polymeric chains were identified by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize changes to the thermal properties of the films as a result of the various treatments. Results indicated that viscosity of the slurries significantly (p< 0.05) increased with increasing chitosan and ethanol concentrations. ATR-FTIR spectra showed that acetic acid/chitosan provided more carboxyl (1442 cm-1) and amine groups (1573 cm-1) within the polymeric network when compared to the lactic acid/chitosan films. The addition of 20% ethanol significantly (p< 0.05) enhanced the drying rate of the film by 30%. However, additional ethanol did not have a significant influence on the solubility and thermal properties of the films. The second part of this dissertation (Chapter 3 and Chapter 4) reports two methods for incorporating vitamin E into the chitosan. Edible chitosan slurries were prepared by blending 250 or 500 mg vitamin E into1.0- 2.0% chitosan. Two blending processes were used to incorporate the vitamin E into the edible slurries: (1) the vitamin E added before lecithin (VE first); and (2) the vitamin E mixed with lecithin (VE mixed) and then added into the slurries. Viscosities of the various formulations, thermal properties, the chemical compositions and solubilities of the film samples were done as mentioned before. High performance liquid chromotagraphy (HPLC) was used to determine the concentration of vitamin E in the films. This study found that vitamin E addition significantly (p< 0.05) affected the rheology of the edible slurries. In addition, viscosity increased with increasing chitosan and vitamin E concentrations. Low chitosan concentrations in the formulation decreased vitamin E incorporating ability, leading to more vitamin E accumulation on the film surface. Solubility decreased with increasing accumulated vitamin E on the film surface. Results also showed that 2.0% chitosan blending with 500 mg VE was superior to the other formulations. More than 73% (368.60± 12.40 mg) of the vitamin E was successfully incorporated in the film. TGA analysis indicated that vitamin E decomposition occurred at 430-450°C. However, DSC thermograms showed no significant difference in glass transition temperature (Tg) and the phase changes in the films.

Consumers have become aware of the potential dangers of a high-fat diet because of numerous diseases associated with obesity. This has caused producers of deep-fried foods to seek new methods to lower the fat content of these foods. The effectiveness of edible films made of various proteins and carbohydrates and the addition of postbreading, prefrying dips of egg albumin solutions have already been proven to lower fat absorption. Common additions of chemicals to films called plasticizers allow them to improve distribution when coating a substrate and improve their water vapor permeability and mechanical properties. The purpose of this study was to attempt to improve the characteristics of egg albumin mediated oil absorption inhibition in deep-fried chicken tenderloin pieces using corn and oat fiber. The use of corn and oat fiber to function as a plasticizer was explored. Dipping samples in an egg albumin dip with no fiber present produced samples with the highest lipid reductions compared to the control. The addition of fiber to any of the dips did not produce a synergistic effect to reduce lipid absorption. The egg dip, 1%, and 2% fiber dip amounts were successful in reducing the lipid content compared to control, but not the 5% fiber dip amount. As the fiber dip concentration decreased for corn and oat fiber, lipid levels decreased. The inability of the 5% fiber dip amount to inhibit oil absorption suggests that the fiber present in the egg dip interfered with its ability to block fat absorption in a concentration dependent manner.

Bad breath (Halitosis) is a health problem occasionally encountered among adults and children. A readily-dissolved edible herbal film was developed. The film contained lyophilized powder of the 80% ethanolic extract of guava leaves (Psidium guajava Linn.), Kaffir lime oil (Citrus hystrix DC.) and other ingredients. The film obtained was of good flexibility, resilient, non-hygroscopic and non-sticky. Sensory evaluation test was carried out, using 9-point Hedonic Scale method. The average score for overall preference was 6.3 (“like slightly” to “like moderately”). Overall appearance, flavor, and texture were evaluated as well. Suppression test was conducted to determine the capability of the film to mask of the odor of the garlic extracts in vitro. It was found that after adding the herbal film to the garlic suspension, all the panelists were not able to detect the garlic odor from the suspension with the corresponding minimum detection concentration of each panelist.

The objectives of this research were (1) to evaluate antimicrobial effects of essential oils incorporated in chitosan edible films against Listeria monocytogenes and Escherichia coli O157:H7, (2) to evaluate effectiveness of the films on a meat product, (3) to characterize physical properties of chitosan films enriched with essential oils, and (4) to determine whether the addition of oregano essential oil to bologna can influence consumer liking of the product. Anise, basil, coriander, and oregano essential oils were tested for antimicrobial activity by paper disc diffusion test with concentration of 1 to 24 ml/disc. Chitosan films incorporated with those essential oils with concentration of 1 to 3 % (3 to 9 ml/disc) were tested for antimicrobial property by film disc diffusion test. Oregano essential oil – chitosan films were applied on thick bologna slices to determine antimicrobial efficacy on a real food product. Solvent extraction and GC/MS analysis were performed to identify and quantify the dominant compounds in oregano essential oil incorporated into the chitosan films before and after application on bologna. Physico–chemical properties of oregano essential oil enriched chitosan films were characterized for thickness, water vapor permeability (WVP), puncture strength, tensile strength, and elongation. The influence of additional oregano EO (45 ppm and 90 ppm) to bologna slices on consumer liking was tested with computerized hedonic scales and just about right scale. Results showed that oregano essential oil exhibited the strongest antimicrobial activity towards L. monocytogenes and E. coli O157:H7 compared to other tested essential oils (oregano >> coriander > basil > anise). Although both tested pathogens were affected, Listeria monocytogenes appeared to be more sensitive to oregano essential oil than Escherichia coli O157:H7. Application of pure chitosan films reduced pathogen counts on meat product (bologna) from 1 to 3 logs and chitosan films enriched with 1 and 2 % oregano essential oil were sufficient for 4 logs reduction of L. monocytogenes and E. coli O157:H7 on bologna slices stored at 10 °C for 5 days. Results of physico–chemical tests showed that addition of oregano essential oil to chitosan films resulted in increased thickness, higher elasticity, reduced puncture and tensile strength, and lower WVP. Application of the films on bologna resulted in increased thickness, higher WVP, higher elasticity, and reduced puncture and tensile strength of the films. Bologna slices covered with chitosan films with 1 % oregano essential oil and stored 5 days at 10 oC absorbed 60 ppm of the EO. Addition of 45 ppm oregano EO did not affect the consuming liking of the product compared to control.