Effects of Antioxidants and Packaging on Lipid and Cholesterol Oxidation and Color Changes of Irradiated Egg Yolk Powder

Dietary cholesterol oxidation products: Perspectives linking food processing and storage with health implications

Dietary cholesterol oxidation products (COPs) are heterogeneous compounds formed during the processing and storage of cholesterol-rich foods, such as seafood, meat, eggs, and dairy products. With the increased intake of COPs-rich foods, the concern about health implications of dietary COPs is rising. Dietary COPs may exert deleterious effects on human health to induce several inflammatory diseases including atherosclerosis, neurodegenerative diseases, and inflammatory bowel diseases. Thus, knowledge regarding the effects of processing and storage conditions leading to formation of COPs is needed to reduce the levels of COPs in foods. Efficient methodologies to determine COPs in foods are also essential. More importantly, the biological roles of dietary COPs in human health and effects of phytochemicals on dietary COPs-induced diseases need to be established. This review summarizes the recent information on dietary COPs including their formation in foods during their processing and storage, analytical methods of determination of COPs, metabolic fate, implications for human health, and beneficial interventions by phytochemicals. The formation of COPs is largely dependent on the heating temperature, storage time, and food matrices. Alteration of food processing and storage conditions is one of the potent strategies to restrict hazardous dietary COPs from forming, including maintaining relatively low temperatures, shorter processing or storage time, and the appropriate addition of antioxidants. Once absorbed into the circulation, dietary COPs can contribute to the progression of several inflammatory diseases, where the absorbed dietary COPs may induce inflammation, apoptosis, and autophagy in cells in the target organs or tissues. Improved intake of phytochemicals may be an effective strategy to reduce the hazardous effects of dietary COPs.

Modifying the Functional Properties of Egg Proteins Using Novel Processing Techniques: A Review

Egg proteins can be used in a wide range of food products, owing to their excellent foaming, emulsifying, and gelling properties. Another important functional property is the susceptibility of egg proteins to enzymatic hydrolysis, as protein digestion is closely related to its nutritional value. These functional properties of egg proteins are likely to be changed during food processing. Conventional thermal processing can easily induce protein denaturation and aggregation and consequently reduce the functionality of egg proteins due to the presence of heat-labile proteins. Accordingly, there is interest from the food industry in seeking novel nonthermal or low-thermal techniques that sustain protein functionality. To understand how novel processing techniques, including high hydrostatic pressure, pulsed electric fields, ionizing radiation, ultraviolet light, pulsed light, ultrasound, ozone, and high pressure homogenization, affect protein functionality, this review introduces the mechanisms involved in protein structure modification and describes the structure-functionality relationships. Novel techniques differ in their mechanisms of protein structure modification and some have been shown to improve protein functionality for particular treatment conditions and product forms. Although there is considerable industrial potential for the use of novel techniques, further studies are required to make them a practical reality, as the processing of egg proteins often involves other influencing factors, such as different pH and the presence of other food additives (for example, salts, sugar, and polysaccharides).

Development of non-dairy creamer analogs/mimics for an alternative of infant formula using egg white, yolk, and soy proteins

OBJECTIVE

A study was conducted to develop non-dairy creamer analogs/mimics using egg white, egg yolk, soy protein and their combinations, and their nutrient content, shelf-life and flavor acceptability were compared.

METHODS

Spray dried egg white, egg yolk, and soy protein isolate were purchased from manufacturers and used for the formulae.

RESULTS

The protein contents of the non-dairy creamer analogs/mimics were about 8.5% as calculated. The amounts of oleic and linoleic acid content increased as the amount of yolk increased in the formula, but the increases of polyunsaturated fatty acids were <0.5% of total fat. Addition of egg yolk to the formula increased choline and lutein content in the products, but the amounts were <0.4 mg/g for choline and 4 μg/g for lutein. The lutein in the products continued to decrease over the storage time, and only about 15% to 20% of the 0-month amounts were left after 3 months of storage. Although the thiobarbituric acid reactive substances values of the spray-dried non-dairy creamer analogs/mimics increased as storage time increased, the values were still low. Yellowness, darkness, and egg flavor/odor of the non-dairy creamer analogs/mimics increased as the amount of egg yolk in the formula increased. The overall acceptability of the non-dairy creamer analogs/mimics was closely related to the intensity of egg flavor/odor, but storage improved their overall acceptance because most of the off-odor volatiles disappeared during the storage. Water temperature was the most important parameter in dissolving spray-dried non-dairy creamer analogs/mimics, and 55°C to 75°C was the optimal water temperature conditions to dissolve them.

CONCLUSION

Higher amounts of yolk and soy protein combinations in place of egg white reduced the cost of the products significantly and those products contained better and balanced nutrients than the commercial coffee creamers. However, off-flavor and solubility were two important issues in the products.

Health Risks of Food Oxidation

The impact of dietary habits on our health is indisputable. Consumer's concern on aging and age-related diseases challenges scientists to underline the potential role of food on the extension and guarantee of lifespan and healthspan. While some dietary components and habits are generally regarded as beneficial for our health, some others are being found to exert potential toxic effects and hence, contribute to the onset of particular health disorders. Among the latter, lipid and protein oxidation products formed during food production, storage, processing, and culinary preparation have been recently identified as potentially harmful to humans. Upon intake, food components are further degraded and oxidized during the subsequent digestion phases and the pool of compounds formed in the lumen is in close contact with the lamina propria of the intestines. Some of these oxidation products have been found to promote inflammatory conditions in the gut (i.e., bowel diseases) and are also reasonably linked to the onset of carcinogenic processes. Upon intestinal uptake, some species are distributed by the bloodstream causing an increase in oxidative stress markers and impairment of certain physiological processes through alteration of specific gene expression pathways. This chapter summarizes the most recent discoveries on this topic with particular stress on challenges that we face in the near future: understanding the molecular basis of disease, the suitability of using living animals vs in vitro model systems and the necessity of using massive genomic techniques and versatile mass spectrometric technology.

Microbial safety and physicochemical characteristics of electron beam irradiated whole egg powder

The effect of electron beam (EB) irradiation on inactivation of foodborne microorganisms and the quality of whole egg powder (WEP) was investigated. WEP sample was irradiated (0, 1, 2, and 4 kGy) and stored for 2 months at 25°C. The D 10 values for Escherichia coli, Listeria monocytogenes, and Salmonella Typhimurium were 0.26, 0.13, and 0.26 kGy, respectively. The L* value increased, while the a* and b* values decreased with increasing irradiation dose. Foaming ability of irradiated samples increased at 0 and 1 months, but not at 2 month. The peroxide value of sample increased both with irradiation and storage. After 1 and 2 months, samples irradiated at 2 and 4 kGy had lower sensory scores for color than those irradiated at 1 kGy. These results suggested that the use of low-dose EB irradiation (≤2 kGy) could improve microbial safety and foaming ability of the WEP with minimal quality changes.

Molecular Regulation of Adipogenesis and Potential Anti-Adipogenic Bioactive Molecules

Adipogenesis is the process by which precursor stem cells differentiate into lipid laden adipocytes. Adipogenesis is regulated by a complex and highly orchestrated gene expression program. In mammalian cells, the peroxisome proliferator-activated receptor γ (PPARγ), and the CCAAT/enhancer binding proteins (C/EBPs) such as C/EBPα, β and δ are considered the key early regulators of adipogenesis, while fatty acid binding protein 4 (FABP4), adiponectin, and fatty acid synthase (FAS) are responsible for the formation of mature adipocytes. Excess accumulation of lipids in the adipose tissue leads to obesity, which is associated with cardiovascular diseases, type II diabetes and other pathologies. Thus, investigating adipose tissue development and the underlying molecular mechanisms is vital to develop therapeutic agents capable of curbing the increasing incidence of obesity and related pathologies. In this review, we address the process of adipogenic differentiation, key transcription factors and proteins involved, adipogenic regulators and potential anti-adipogenic bioactive molecules.

Effects of dietary supplementation with Gynura procumbens (Merr.) on egg yolk cholesterol, excreta microflora and laying hen performance

Abstract 1. The present study investigated the effects of dietary supplementation with Gynura procumbens on egg yolk and serum cholesterol and triglycerides, excreta microflora, laying performance and egg quality. 2. A total of 160 Hy-Line Brown layers (45 weeks old) were randomly assigned into 4 treatments on the basis of laying performance. Each treatment had 4 replicates with 10 birds each. 3. Dietary treatments were basal diet supplemented with 0 (control), 2.5, 5.0 and 7.5 g/kg diet G. procumbens during 56-d feeding period. 4. Serum (d 21, 42 and 56) and egg yolk (d 28, 42 and 56) cholesterol and triglycerides concentrations were linearly reduced with increasing dietary concentrations of G. procumbens. 5. Increasing dietary concentrations of G. procumbens linearly reduced the excreta total anaerobic bacteria (d 28), Clostridium sp. and Escherichia coli (d 28 and 56) populations. 6. Overall egg production and egg mass were linearly increased, and overall feed efficiency was linearly improved with increase in dietary G. procumbens. 7. Dietary increasing concentrations of G. procumbens linearly improved egg yolk colour (d 28 and 56) and breaking strength of eggs (d 56). 8. The results obtained in the present experiment indicate that dietary supplementation with G. procumbens could reduce the egg yolk cholesterol, suppresses harmful excreta microflora and improves layers performance.

Effect of irradiation and packaging conditions after cooking on the formation of cholesterol and lipid oxidation products in meats during storage

The effect of irradiation and packaging conditions on the content of cholesterol oxidation products (COPs) and lipid oxidation in cooked turkey, beef, and pork during storage was studied. Ground turkey leg, beef, and pork were cooked, packaged either in oxygen-permeable or oxygen-impermeable bags, and irradiated at 0 or 4.5 kGy. Lipid oxidation and COPs were determined after 0 and 7 days of storage at 4°C. Packaging of cooked meat was more important than irradiation in developing COPs and lipid oxidation in cooked meats during storage. 7α-Hydroxycholesterol, 7β-hydroxycholesterol, β-epoxide, and 7-ketocholesterol were among the major COPs formed in cooked turkey, beef, and pork after storage, and their amounts increased dramatically during the 7-day storage in aerobic conditions. Irradiation had no significant effect on the amounts of any of the COPs found in cooked turkey and beef, but increased (P<0.05) the amounts of α- plus 7β-hydroxycholesterol, β-epoxide, 7-ketocholesterol, and total COPs in aerobically packaged cooked pork. The amounts of COPs and lipid oxidation products (TBARS) closely related to the proportion of polyunsaturated fatty acids in meat. The results indicated that the composition of fats in meat is important on the oxidation rates of lipids and cholesterol, and packaging is far more important than irradiation in the formation of COPs and lipid oxidation in cooked meat.

Inhibitory action of conventional food-grade natural antioxidants and of natural antioxidants of new development on the thermal-induced oxidation of cholesterol

Cholesterol is a molecule with an unsaturated bond; therefore, like polyunsaturated fatty acids, it is prone to oxidation. Cholesterol oxidation products (COPs) are found in many common foods and have been shown to be atherogenic, cytotoxic, mutagenic and possibly carcinogenic. Therefore, efforts to prevent or to avoid COPs formation during manufacture and/or processing of foods are of high priority. The effect of natural antioxidants on COPs formation has not been extensively studied. We assayed the effect of some widely applied natural antioxidants, such as tocopherol homologs (alpha-T, gamma-T, and delta-T) and rosemary extract, and of some natural products of newly developed as antioxidants, such as the flavonoids quercetin, catechin, morin, and rutin, and also of an alkaloid-derived product, boldine, to inhibit cholesterol oxidation of soybean oil, added of cholesterol, induced in the Rancimat test conditions (150 degrees C and air bubbling). Formation of six different COPs at the induction period and at the 100 microS conductivity value was monitored by gas chromatography. Under the experimental conditions gamma-T, quercetin, and rosemary extract prove effective to inhibit both soybean oil oxidation and COP formation. alpha-T, catechin, and morin are less efficient to prevent COP formation. delta-T, rutin and boldine are devoid of protective action against COP formation. gamma-T, quercetin and rosemary extract may inhibit COP formation from the nucleus and from the lateral chain of the cholesterol molecule.

Effect of irradiating shell eggs on quality attributes and functional properties of yolk and white

Shell eggs were irradiated and the physico-chemical, and functional properties of egg yolk and white were determined. The color of egg yolk was not affected, but the viscosity of egg white was dramatically lowered and became watery by irradiation. The foam capacity and foam stability of egg white were significantly decreased due to protein oxidation by irradiation. However, the texture characteristics of egg white were not changed by irradiation, indicating that irradiation may not alter the thermal characteristics of egg white proteins. Sulfur volatiles were generated by irradiation but disappeared during storage under aerobic conditions. Because egg white became watery, irradiation may not be advisable for table eggs but may be useful for pasteurizing liquid egg white or liquid whole egg without significant deterioration of their quality and functionality. In particular, the dramatic decrease in the viscosity of egg white by irradiation will improve flow of liquid egg white or liquid whole egg, which could be highly useful for egg processing.