Interfacial and Rheological Properties of Oil-In-Water Emulsions as Affected by Egg Yolk From Different Sources

Hen egg yolk is an essential ingredient for the preparation of a large variety food emulsions, such as mayonnaises, salad dressings and creams. The preparation and long-term stability of this kind of food are influenced by the solution pH. However, the emulsifying properties of duck and goose egg yolk remain unknown as they have not been clearly documented. In this study, the emulsion properties (droplet size, solubility, and viscosity), interface attributes (interfacial protein concentration, percentage of adsorbed proteins, SDS-Page profiles of adsorbed proteins and interfacial tension) and rheological properties (thixotropic behavior) of oil-in-water emulsions prepared with hen, duck and goose egg yolks were examined. These features were observed at three different pHs (3, 6 and 9). Results showed that pH 6 provided the best conditions for preparing emulsion using the three types of egg yolks. The droplet size of goose egg yolk emulsions at pH 6 was the smallest than other types of egg yolk at all pH levels. The protein solubility was lower at pH 6 for all types of egg yolk emulsions. The viscosities of hen, duck and goose egg yolk emulsions at pH 6 were higher than those at pH 3 and 9. In the pH range studied, the interface attributes were better at pH 6 for all types of egg yolks. The interfacial protein concentration was higher at pH 6 for the three types of yolks (1.70 mg m⁻², 1.74 mg m⁻² and 1.98 mg m⁻², respectively) than at pH 3 and pH 9. At pH 6, most of the proteins from the three yolks were adsorbed at the interface and the interfacial tension at steady-state was lower (10 mN m⁻¹, 13.98 mN m⁻¹ and, 8.37 mN m⁻¹ respectively) than at pH 3 or pH 9. At pH 3, proteins at the interface were mainly phosvitin, and at pH 9, some apoproteins of HDL and LDL were detected. The pH modulates the composition of yolk proteins at the interface, mainly by modifying the net charge of the proteins causing their repulsion or dimerization. The micrographic observation showed that the oil droplets were more uniform at pH 6 than those at pH 3 and 9 for all types of egg yolk emulsions. At pH 6, all of the egg yolk emulsions exhibited thixotropic shear thinning behavior under steady shear test. Emulsions produced at pH 3 and 9 exhibited closely the Newtonian behavior. These results suggested that hen, duck and goose egg yolk are able to provide stabilizing effects at pH 6. This study shows a good potential for goose and duck egg yolk to be used as an alternative emulsifying agent in the food industry

Development of Jackfruit Crackers: Effects of Starch Type and Jackfruit Level

Crackers are one of the convenient and inexpensive snacks that have high market potential.  Most of the commercial crackers are carbohydrate-rich and normally considered as a low value-added product.  In this study, innovative value added crackers made of jackfruit were developed.  The effect of starches (sago and cassava) and levels of jackfruit (30 and 50%, w/w) on characteristics of the crackers were investigated.  Physicochemical properties of the products at each predetermined processing steps (steaming, drying and frying); bulk density, expansion ratio, color and carotenoid contents were measured.  A decrease in jackfruit level resulted in crackers with lower bulk density (0.26 to 0.41 g/cm3) and higher volume expansion ratio (2.84 to 4.66 cm3).  Blending the cassava and sago starch at 1:1 ratio resulted in lower bulk density and higher expansion ratio compared to crackers made with a single type of starch.  The L* and b* values decreased with drying and frying process, indicative of Maillard reactions.  The higher L* value was influenced by the starch content, while higher jackfruit led increased the b* values, attributed to the presence of pigments in the fruit.  Total carotenoid contents of fried crackers increased following steaming process, ranging from 0.061 to 0.199 mg/100g and samples made with blend of sago and cassava has the highest carotenoid contents.  A jackfruit level of 30% (w/w) made with blend of sago and cassava starches (1:1) produced fried crackers with the most acceptable physicochemical characteristics.  Crackers with improved nutritional value can be developed by incorporating jackfruit, thus expanding the conventional use of the fruit

Effect of storage temperature on the antioxidant properties of active bilayer polyethylene/soy protein isolate (PE/SPI) film

Polyethylene (PE) is considered to be one of the most widely used plastic in the world due to its vast array of applications depending on the particular type. It is well known that petroleum-based plastic is a good material for food packaging for its good mechanical properties. Meanwhile, biopolymer films have poor mechanical and water barrier properties compared to conventional plastics. Soy protein isolate (SPI) with mangosteen pericarps extract (MPE) was laminated on PE film to form a bilayer film with antioxidant property. The PE/SPI film was stored at two different temperatures; 25°C and accelerated temperature at 40°C for 9 weeks. The color and opacity of the film increased significantly (P ≤ 0.05) after 9 weeks observation. There is no change in the morphology of the film after 9 weeks stored at both temperatures. The antioxidant properties of film were measured by total phenolic content (TPC) and 2,2-diphenyl-1- picrylhydrazyl (DPPH) scavenging assay for each week interval. The antioxidant activities of films decreased significantly (P≤0.05) throughout the storage time at both temperatures. Higher temperature also reduced the antioxidant properties of bilayer film significantly (P ≤ 0.05). Addition of mangosteen pericarps extract contributes to the enhanced antioxidant properties of bilayer film

Kenaf (Hibiscus cannabinus L.) seed and its potential food applications: a review

Kenaf belongs to the family Malvaceae noted for their economic and horticultural importance. Kenaf seed is a valuable component of kenaf plant. For several years, it has been primarily used as a cordage crop and secondarily as a livestock feed. The potential for using kenaf seeds as a source of food-based products has not been fully exploited. Consumers are becoming more interested in naturally healthy plant-based food products. Kenaf seed, the future crop with a rich source of essential nutrients and an excellent source of phytocompounds, might serve suitable roles in the production of value-added plant-based foods. At present kenaf seed and its value-added components have not been effectively utilized for both their nutritional and functional properties as either ingredient or major constituent of food products. This review focuses on the possible food applications of kenaf seed and its value-added components based on their nutritional composition and functional properties available in literature, with the purpose of providing an overview on the possible food applications of this underutilized seed. The review focuses on a brief introduction on kenaf plant, nutritional function, lipids and proteins composition and food applications of the seed. The review elaborately discusses the seed in terms of; bioactive components, antioxidants enrichment of wheat bread, antimicrobial agents, as edible flour, as edible oil and a source of protein in food system. The review closes with discussion on other possible food applications of kenaf seed. The need for food scientists and technologists to exploit this natural agricultural product as a value-added food ingredient is of great significance and is emphasized

Polyphenol compounds from pomegranate (Punica granatum) extracted via various methods and its application on meat and meat products: a review

Recently natural polyphenol compounds (PCs) of plants, gained wide consideration of scientists, companies and public people because of its unique pharmaceutical and preservative benefits in the physiological system. They can prevent mortal and serious diseases such as cancer, cardiovascular and Alzheimer. However, defining a suitable source of PCs and their proper, economic and efficient extraction method are still a challenge. The aim of this study was to review PCs as an important antioxidant, the significance of pomegranate as a source of natural PCs and its application in meat and meat product. This study also covers different types of PCs extraction methods such as solid-liquid extraction (SLE) method as a conventional extraction which using Soxhlet apparatus and several solvents and advanced methods such as microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), accelerated solvent extraction (ASE), ultrasound-assisted extraction (UAE) and high hydrostatic pressure extraction (HHPE). Simple and developed analytical method of PCs is also reviewed in the study. SLE method is an easy and simple method but, it uses lots of chemicals and is not suitable for all kinds of PCs extraction. UAE is using for quick extraction PCs, SFE is green extraction method uses less solvent and have a good result but it needs high technology. ASE method is a proper alternative for Soxhlet extraction method for its quick result. MAE method has high extraction result but is not suitable for some thermolabile PCs. Several parts of pomegranate showed antioxidant and antimicrobial traits for shelf life extension of meat and meat product. Pomegranate peel is the strongest antioxidant followed by pomegranate juice and seed. Pomegranate peel prolonged chilled chicken meat shelf live up to three weeks

Application of supercritical carbon dioxide (SC-CO2) on the microbial and physicochemical quality of fresh chicken meat stored at chilling temperature

Supercritical carbon dioxide (SC-CO2) is a non-thermal technique implemented by food, pharmaceutical, and similar industries with the aim of inhibiting the microorganisms and apply effective sterilisation. Presently, limited number of studies has reported the application of SC-CO2 on fresh chicken meat. The present work therefore aimed to reveal the microbial and physicochemical quality of the SC-CO2-treated fresh chicken meat. The fresh chicken meat was subjected to the SC-CO2 at 14 MPa and 45°C for 40 min and was stored at 4°C for 0, 3, and 7 days. The obtained results indicated that the treatment with SC-CO2 significantly decreased the total plate count and, yeast and mould count from log10 5.90 to 2.00 CFU/g and from log10 5.02 to 2.00 CFU/g at day 7 of storage, respectively. The values of pH, cooking loss, and water holding capacity were not affected by the treatment. The results revealed that the SC-CO2-treated samples displayed harder texture, higher lightness and yellowness, and lower redness. In addition, lipid peroxidation of SC-CO2 and control samples resulted in values of 1.9 and 0.5 MDA/mg of meat at day 7 of storage time and did not significantly change in the rest of the evaluation days. In summary, the application of SC-CO2 was capable of enhancing the microbial quality and certain physicochemical attributes. However, alteration of certain parameters of SC-CO2 might enhance the overall meat quality

Effect of addition of resistant starch on oxidative stability of fried fish crackers as influenced by storage temperatures and packaging materials

The aim of the present work was to investigate the effect of the addition of resistant starch (unmodified potato starch) on physicochemical properties and lipid stability of fried fish crackers packed in two types of packaging. Fish crackers added with one part of resistant starch were prepared, packed into two types of packaging with four different layers of packaging material; (i) polyethylene terephthalate-polyethylene-aluminium-linear low density polyethylene and (ii) oriented polypropylene-polyethylene-metallized polyethylene terephthalate-linear low density polyethylene and stored at 25, 40 and 60°C for 12 weeks. The linear expansion and oil absorption of the fried fish cracker were 58.00 ± 3.46% and 12.60 ± 1.34% respectively. Physical analyses showed an increase in moisture contents (from 2.75-3.47% to 4.08-4.54%), water activities (0.297 to 0.436aw) and a* and b* values (5.27 to 9.14% and 21.09 to 25.27%, respectively), while a decrease in L* value (from 63 to 58%), hardness (from 2.110 to 1.117 kg) and crispiness (from 12.46 to 8.18 kg/sec) throughout 12 weeks of storage at all temperatures tested. The lipid yield of the crackers increased during the storage time and the concentrations of conjugated dienes and thiobarbituric acid reactive substances showed a gradual increase and decrease, respectively. These results showed that the fried fish crackers in the storage study had undergone lipid oxidation where physical and chemical deterioration were observed and measured. In conclusion, the addition of one part of resistant starch in crackers has given positive effect on the stability of the resulting fried fish crackers

Kenaf (<em>Hibiscus cannabinus</em> L.) Seed Extract as a New Plant-Based Milk Alternative and Its Potential Food Uses

Kenaf (Hibiscus cannabinus L.) seed is rich in protein, fat, fiber, and other essential nutrients. Kenaf seed comprises of high protein (22–31%) and oil (22–25%) contents which suggested its high potential food application. This chapter discusses the potential and early development of kenaf-based plant-milk and tofu. The step-by-step processes involved in preparation of kenaf-based milk and kenaf-based tofu at laboratory-scale are illustrated. Soaking conditions (temperature and time) of kenaf seed as pretreatment in preparation of kenaf seed milk were highlighted. Hydration of kenaf seed were found to be faster at elevated temperature, however higher soaking temperature and prolonged soaking time causes some losses of protein (%) and solid content (%) which are unfavorable for production of highly nutritious plant-based milk. Furthermore, in preparation of kenaf-based tofu, soaking temperature of seed also affected the properties of the tofu. As the soaking temperature was increased from 25–65°C, the yield, hardness, and chewiness of kenaf tofu decreased. It was recommended that soaking of kenaf seed at 25°C and the use of aluminum potassium salt at 1.00 g% as coagulant produces kenaf-based tofu with optimum quality

Characterization of heat-moisture treated Dioscorea alata purpurea flour: impact of moisture level

Purpose: Edible bird’s nest (EBN) has been considered as one of the nutritious foods and was also claimed to aid in digestion problems. Potential prebiotic of the EBN for gut health by the presence of glycan within the complex structure of the EBN glycoprotein to date has not been reported. The gut health can contribute to the overall consumers’ health in the improvement of the gut beneficial bacterial growth. In this study, the potential prebiotic of the EBN was conducted using a simulation of in vitro human colon model system. Methods: The EBN-extracted glycan and EBN glycoprotein (crude sample) were digested using in vitro oral, gastric and duodenal model system. Prebiotic activities of the undigested EBN glycan and EBN glycopeptide compounds were studied with the fructooligosaccharide as a positive control, using inoculum of 10% (w/v) faecal bacteria in the in vitro fermentation system. Result: The fermentation of EBN glycan and EBN glycopeptide had shown significant increases of the gut beneficial bacteria and was comparable with fructooligosaccharide fermentation, with each sample presented different profiles of bacterial growth. The fermentation of EBN glycan and EBN glycopeptide demonstrated an increase in the total short-chain fatty acid production, particularly acetate, propionate and butyrate. Conclusion: These findings suggested that the EBN can be functioned as a natural prebiotic upon consumption, thus providing apotential as prebiotic ingredients

Extraction of pomegranate peel and green tea leaves and their effects on the microbial, physicochemical, microstructural and sensorial properties of chilled-stored chicken meat

Pomegranate (Punica granatum L.) peel extracts (PPE) and green tea (Camellia sinensis) leaves extracts (GTE) have the potential to be the natural preservatives to prolong the chicken meat quality stored in chilling temperature. The first part of this work aimed to determine the effects of solid-liquid extraction (SLE) and ultrasound-assisted extraction (UAE) in extracting the pomegranate peel and green tea leaves. The second part was to determine the microbial, physicochemical, microstructural and sensorial properties of chicken meat applied with the PPE, GTE or PPE+GTE and stored in chill temperature for seven days. UAE method resulted in higher antioxidant activity in PPE and GTE at 74.3% and 70.4%, respectively compared to SLE method at 48.2% and 41.5%, respectively. The GTE inhibited the microbial growth with 5.47 and 5.96 log CFU/g of the chicken meat at the third and seventh day of chilled-storage, respectively. The water holding capacity, pH, lipid peroxidation and texture were not affected by the extracts. GTE affected the chicken meat by increasing the yellowness (b*), changing the microstructure, and reducing the sensory acceptability. Overall, GTE can to be used as a natural preservative for chilled chicken meat, however, further additional treatments are needed to overcome the negative effect on the chicken meat characteristics