黄花鱼腌制加工过程的脂肪氧化分析

目的 阐明多脂黄花鱼(yellow croakers)腌制加工过程的理化变化对脂肪氧化的影响以及脂肪氧化的内在机制。方法 通过测定大黄鱼腌制加工过程中鱼肉理化指标(水分、盐分、pH值), 脂质氧化指标[硫代巴比妥酸值(TBARs 值)、过氧化值(POV值)]及脂肪氧合酶(LOX)活力的变化, 研究加工过程中脂质分解氧化规律及其与水分、盐分、pH、LOX活力的相关性。结果 随着加工的进行, 水分出现3次显著性减少(P<0.05), 分别在腌制3 d、烘干1 d以及成品; 盐分在腌制3 d时达到最高值6.38%; 氧化指标POV和TBARs都呈现先升后降的趋势, 分别在腌制3 d和烘干1 d达到最高值为0.907 meq/kg和0.250 mg/kg; LOX活性则呈现递减的趋势。POV值仅和盐分呈显著正相关(P<0.05), TBARs则分别和盐分、水分呈极显著正、负相关(P<0.01), LOX酶活与盐分、TBARs呈极显著负相关(P<0.01)。结论 在多脂黄花鱼的腌制过程中, 适当的盐度和水分的减少可促进脂肪氧化, 而脂肪氧合酶的活性可被盐抑制, 酶促反应不是引起脂肪氧化的主要原因。     

产酸丙酸杆菌发酵甘油提取物对冷藏调理猪肉饼品质的影响

以未添加抗氧化剂的调理猪肉饼作为对照,研究不同添加量的产酸丙酸杆菌发酵提取物（fermented extract of Propionibacterium acidipropionici,FEPA）对4 ℃冷藏调理猪肉饼品质的影响。将0.2%（以猪瘦肉质量计,下同）、0.3%、0.4%和0.5%的FEPA分别添加到调理猪肉饼中,测定其在1、4、7、10 d冷藏期间的pH值、色泽（L*、a*、b*值）、质量损失率、硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARS）值、菌落总数和质构变化。结果表明：添加FEPA可显著提高调理猪肉饼冷藏期间的a*值（P＜0.05）,有利于猪肉饼色泽的改善,并能显著降低猪肉饼的咀嚼性、质量损失率、菌落总数（P＜0.05）,显著抑制蛋白和脂肪氧化（P＜0.05）;其中添加0.5%的FEPA可显著降低猪肉饼的硬度（P＜0.05）,且其抑制蛋白、脂肪氧化和抗菌效果最佳,因此在所有处理组中,0.5%的FEPA对调理猪肉饼的品质有较优的改善作用。     

Natural Products Inhibit Oxidative Rancidity in Salted Cooked Ground Fish

The extent of lipid oxidation in salted cooked ground fish treated with several natural products (polyphenols, dried spices and fresh spices) was measured by the production of thiobarbituric acid reactive sub-stances (TBARS). The fresh spices, ginger and tumeric, were more potent than garlic and onion (at 10% conc) in inhibiting lipid oxidation in salted cooked ground fish. The order of antioxidative potency of the dried spices was: cloves > cinnamon > cumin ～ black pepper > fennel ～ foenugreek. The dried spices were more effective antiox-idants than fresh spices. The polyphenols were the most potent group of natural antioxidants. The order of potency of the polyphenols (0.01% concentration) was: ellagic acid > tannic acid > myricetin > quercetin.     

Effect of natural antioxidants on stored freeze-dried food product formulated using horse mackerel (Trachurus trachurus)

The physical and chemical properties of Trachurus trachurus (horse mackerel) as well as a food product in the presence and absence of natural antioxidants, were investigated. The rate of lipid oxidation in the freeze-dried horse mackerel product stored at room temperature (22 °C) was investigated, using peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and hexanal concentration to determine primary, secondary and tertiary oxidation products. Natural antioxidants were used to slow down oxidation processes and to improve nutritional and eating quality. These included vitamin E + vitamin C + citric acid (250, 250, 100 mg kg⁻¹, respectively), vitamin E + vitamin C + citric acid + rosemary (250, 250, 100, 250 mg kg⁻¹, respectively) and rosemary (250 mg kg⁻¹). Biochemical analysis such as PV and TBARS measurements showed that the combination of vitamin E + vitamin C + citric acid (250, 250, 100 mg kg⁻¹) were found to be the most significant (P ≤ 0.01) in controlling the rate of lipid oxidation in freeze-dried food followed by rosemary (250 mg kg⁻¹). There was an initial rise in the PV of all samples, which dropped after 8 weeks, because of formation of secondary oxidation products. The rise in PV was much higher in the control samples with no antioxidants added, compared with the antioxidant-treated samples. Combinations of E + C + citric acid treatment group followed by rosemary alone were the most significant in lowering PV, hence, reducing formation of primary oxidation products (P ≤ 0.01). Once the primary oxidation products were lowered, TBARS levels (secondary oxidation products) increased in control samples after 12 weeks; however, in E + C + citric acid treatment group and rosemary-treated samples, this increase was significantly lower (P ≤ 0.01). There was a rise in hexanal concentration for up to 8 weeks, which dropped only in the antioxidant-treated groups and continued to rise in the control samples.     

Effect of Phosphatidic Acid and Phosphatidylserine on Lipid Oxidation in Beef Homogenate During Storage and in Emulsified Sardine Oil

A study on the effect of exogenously added 2 anionic phospholipids, phosphatidylserine (PS), and phosphatidic acid (PA), against lipid oxidation in food systems was carried out using cooked beef homogenate and emulsified sardine oil. Measurements of thiobarbituric reactive‐substances (TBARS) showed a pronounced inhibitory effect of egg yolk PA and dipalmitoyl PA on the oxidation of beef homogenate during storage at 4 EC for 6 d. The addition of dipalmitoyl PA to emulsions of fish oil effectively suppressed the hemoprotein‐induced lipid oxidation. Meanwhile, the addition of dipalmitoyl PA and bovine brain PS to emulsions of fish oil suppressed the nonheme iron ion‐induced lipid oxidation. Therefore, the unique protective effect of PA against the oxidation of beef homogenate could be partly explained by the suppression of the catalytic activity of nonheme iron and hemoprotein. Abbreviations Used: BBPS, bovine brain phosphatidylserine; DPPS, dipalmitoyl phosphatidylserine; DPPA, dipalmitoyl phosphatidic acid; EYPA, egg yolk phosphatidic acid; EYPC, egg yolk phosphatidylcholine; PE, phosphatidylethanolamine; TBARS, thiobarbituric acid‐reactive substances; Hepes, 2‐[4‐(2‐hydroxyethyl)‐1‐piperazinyl] ethanesulfonic acid; LPC, lysophosphatidylcholine; LPE, lysophosphatidylethanolamine; TLC, thin‐layer chromatography.     

洋葱皮乙醇提取物对冷却牛肉颜色、脂质和蛋白质氧化稳定性的影响

将牛肉切片在3种浓度（0.5 %、1.0%、2.0%）的洋葱皮乙醇提取物（Ethanol Extract of Onion Skin,EEOS）溶液中浸渍后在4 ℃条件下冷藏12 d,并与空白对照组和添加了抗坏血酸（ascorbic acid,V_C）的处理组进行比较,分析EEOS对牛肉在冷藏期间的颜色褐变、脂肪和蛋白质氧化以及腐败程度的影响。结果表明:EEOS总酚含量较高,具有很强的自由基清除活性;添加EEOS可延缓牛肉pH上升,提高颜色稳定性,减少高铁肌红蛋白的生成,同时延缓脂肪和蛋白的氧化进程。2% EEOS有效降低了牛肉样品硫代巴比妥酸反应物（Thiobarbituric acid reactive substances,TBARS）和蛋白质羰基含量,与空白对照组相比分别降低56.9%和17.6%。此外,2% EEOS还可显著降低挥发性盐基氮（Total Volatile Basic Nitrogen,TVB-N）的含量（P<0.05）。因此,添加2% EEOS可抑制牛肉冷藏期间的颜色褐变和脂肪、蛋白质的氧化,可在牛肉冷藏保鲜中作为天然抗氧化剂。     

Impact of Added Encapsulated Phosphate Level on Lipid Oxidation Inhibition during the Storage of Cooked Ground Meat

The effect of levels (0.1%, 0.2%, 0.3%, 0.4%, 0.5%) of added encapsulated (e) phosphate (sodium tripolyphosphate, STP; sodium hexametaphosphate, HMP; sodium pyrophosphate, SPP) on lipid oxidation inhibition during storage (0, 1, and 7 d) of ground meat (chicken, beef) was evaluated. The use of eSTP and eSPP resulted in lower and higher cooking loss (CL) compared to eHMP, respectively (P < 0.05). Increasing encapsulated phosphate level (PL) enhanced the impact of phosphates on CL in both chicken and beef samples (P < 0.05). Encapsulated STP increased pH, whereas eSPP decreased pH (P < 0.05). pH was not affected by PL. The highest orthophosphate (OP) was obtained with eSTP, followed by eSPP and eHMP (P < 0.05). The level of OP determined in both chicken and beef samples increased (P < 0.05) during storage. Increasing PL caused an increase in OP (P < 0.05). The highest reduction rate in the formation of thiobarbituric acid reactive substances (TBARS) and LPO for both meat species were obtained with eSPP, followed by eSTP and eHMP (P < 0.05). Increasing PL resulted in lower TBARS and LPO (P < 0.05). Findings suggest that encapsulated phosphates can be a strategy to inhibit lipid oxidation for the meat industry and the efficiency of encapsulated phosphates on lipid oxidation inhibition can be enhanced by increasing PL.     

Antioxidant activity of ethanolic extract of Cortex fraxini and use in peanut oil

Cortex fraxini was extracted with 95% ethanol to obtain a crude antioxidant extract. The antioxidant activity was evaluated using the linoleic acid peroxidation method and the free radical scavenging assays, namely 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. Cortex fraxini extract (CFE) showed high inhibition of peroxidation of linoleic acid when compared with butylated hydroxytoluene (BHT). CFE also exhibited excellent scavenging activity on DPPH and hydroxyl radicals. Total antioxidant activity was measured by the reduction of Mo(VI) to Mo(V) by the extract, and subsequent formation of a green phosphate/Mo(V) complex at acid pH. CFE had significant total antioxidant activity and the effects were increased with increasing reaction time. The total phenolic content of the sample, analyzed by using Folin–Ciocalteu’s reagent, was 91.33 mg/g dry weight expressed as pyrocatechol equivalents. Then the suitability of CFE as an antioxidant was determined in peanut oil, and the decrease of lipid oxidation was monitored using thiobarbituric acid-reactive substances (TBARS) assay. CFE treatment significantly (P < 0.05) reduced lipid oxidation in peanut oil compared to the control. No significant differences (P = 0.05) in lipid oxidation were detected between CFE antioxidant and BHT antioxidant samples.     

不同干制方式对蓝点马鲛脂肪氧化和挥发性风味成分的影响

为探究不同干制方式对水产品脂肪氧化与挥发性风味物质组成的影响,以蓝点马鲛（Scomberomorus niphonius）为原料,采用热风干制、冷风干制和传统自然晾晒法制得对应实验组样品。测定了原料和不同实验组样品的水分质量分数、pH、脂肪含量、酸价（Acid value,AV）、过氧化值（Peroxide value,POV）、丙二醛（Malondialdehyde,MDA）、脂肪酸组成和挥发性风味物质等指标。结果显示:三种干制方式制得的样品的水分质量分数均在30%左右;pH始终保持在6以上;冷风干制组的AV、POV和MDA含量整体较低（P<0.05）;热风干制组中脂肪含量下降最多,AV含量最高,POV和MDA含量显著低于自然晾晒组（P<0.05）;自然晾晒组中AV含量最低,POV和MDA含量显著高于其他组别（P<0.05）。干制样品中不饱和脂肪酸尤其是ω-3多不饱和脂肪酸含量下降显著（P<0.05）,其中自然晾晒组下降最为明显。原料和干制样品中共检出了8大类120种挥发性风味成分,主要由醛类、醇类和酯类构成。经主成分分析3个主成分对风味的累计贡献率达99.9%,其中自然晾晒组的总体评分最高。结果表明干制方式对蓝点马鲛的脂肪氧化程度和风味均有较大的影响,其中自然晾晒组风味更佳。本研究为传统的水产品加工行业的技术转型提供有效的数据支撑和发展方向。     

花椒提取物对调理猪肉饼冷藏期间品质的影响研究

探究不同添加量的花椒提取物对调理猪肉饼冷藏期间品质及氧化程度的影响。将0.01%、0.02%和0.03%的花椒提取物添加到调理猪肉饼中,研究其在1、4、7、10 d冷藏期间的pH、颜色、质构、硫代巴比妥酸值(thiobarbituric acid reactive substance,TBARS)和巯基值的变化,并与0.02%二丁基羟基甲苯(butylated hydroxytoluene,BHT)作比较。研究结果表明,添加花椒提取物对调理猪肉饼冷藏期间的pH、颜色无显著影响(p>0.05),在一定程度上降低了其硬度和咀嚼性。此外,添加花椒提取物可显著降低猪肉饼脂肪氧化和蛋白质氧化程度(p<0.05)。当添加量为0.01%和0.02%时,花椒提取物处理组抑制脂肪氧化的效果与0.02%的BHT效果相当,而当添加量增加至0.03%时,花椒提取物组抗脂肪氧化效果优于0.02%的BHT,且其蛋白氧化程度在整个冷藏期间均显著低于对照组(p<0.05),表明花椒提取物可有效抑制猪肉饼中脂肪和蛋白质氧化,其中0.03%花椒提取物组效果最好,甚至优于0.02%的BHT。     

Antioxidative properties of onion peel extracts against lipid oxidation in raw ground pork

Onion peels extracted with various concentrations of ethanol were examined for their extraction yield, total phenolic content, DPPH scavenging activity, and reducing power. Onion peel extracted with 50% ethanol exhibited higher extraction yields, total phenolic content, and DPPH scavenging activity than extracts from distilled water, 70 or 95% ethanol. Thus, the antioxidative efficiency to inhibit lipid oxidation of ascorbic acid (0.05%) and 50% ethanol extract of onion peel (0.05, 0.1, and 0.2%) in raw ground pork was investigated during chilled storage (16 days). The pH of the samples decreased considerably during storage (p<0.05). Addition of ethanol onion peel extract significantly improved the thiobarbituric acid reactive substances and peroxide values in raw ground pork meat (p<0.05). Therefore, onion peel extract by 50% ethanol is a very effective inhibitor of lipid oxidation and has potential as a natural antioxidant in raw ground pork.     

八角茴香提取物对牛肉丸脂肪氧化和品质特性的影响

为研究八角茴香提取物对牛肉丸脂肪氧化和品质特性的影响,选择不同浓度的八角茴香提取物(0.01%、0.03%和0.05%)加入到牛肉丸中,测定牛肉丸在4 ℃冷藏过程中的pH、颜色(a*、b*、L*)、硫代巴比妥酸值(TBARS)、亚硝酸盐残留量和出品率,并对其进行感官评价。结果表明:与空白对照组相比,添加0.05%八角茴香提取物在整个冷藏过程中,显著降低了牛肉丸的pH、硫代巴比妥酸值和亚硝酸盐残留量(p<0.05)。八角茴香提取物在添加量为0.03%时,与空白对照组相比显著提高了冷藏3 d的红度值(p<0.05),而添加0.01%时,显著提高了冷藏5 d后的红度值(p<0.05)。八角茴香提取物改善了牛肉丸的滋气味、组织状态、酸败味及总体接受程度。综上,八角茴香提取物能够有效抑制冷藏牛肉丸脂肪的氧化,并能够改善其品质特性,具有较高的应用价值。     

Prooxidant effects of the combination of green tea extract and sodium nitrite for accelerating lipolysis and lipid oxidation in pepperoni during storage

Abstract: The individual and interactive effects of green tea (GT) extract and sodium nitrite (NT) on lipolysis and lipid oxidation were investigated in pepperoni during processing and storage (4 °C). Pepperoni was treated with GT at concentrations of 0.02%, 0.05%, 0.1%, 0.2%, 0.5%; and NT from 0.003% to 0.015% in increments of 0.003%; and a combination of 0.05% GT and 0.009% NT (GT/NT). The pH, color, residual nitrite, fatty acid (FA), and 2‐thiobarbituric acid reactive substances (TBARS) values were measured. The results showed inhibitory effects on TBARS value were concentration dependent. The largest effect was at 0.05% for GT and 0.009% for NT. Adding 0.05% GT significantly decreased (P < 0.05) the TBARS values but did not affect color values during storage. NT (0.009%) was more effective than GT (0.05%) for maintaining lower TBARS values (P < 0.05). Total fatty acids were not affected by 0.05% GT and 0.009% NT treatments. However, adding GT/NT showed a significant prooxidant effect (P < 0.05) in pepperoni, which accelerated lipolysis and lipid oxidation significantly (P < 0.05) during storage, with depletion of nitrite. This suggests that adding GT and an appropriate amount of NT into pepperoni could promote lipolysis and lipid oxidation during storage, as compared to NT alone. Practical Application: When using GT extract as an antioxidant in industrial production of pepperoni, the interaction effect with NT should be considered, as it may lead to a prooxidant effect during refrigerated storage.     

Effect of Protein Disruption by Denaturation and Hydrolysis on Egg Yolk Lipid Oxidation

Egg yolk (20%, w/w) was added to 1,3, and 6M guanidinium chloride (Gnd C1) solutions and agitated at 23°C. Thiobarbituric acid reactive substances (TBARS) were measured over a 2 week period. Increasing concentrations of Gnd C1 resulted in more rapid development of TBARS. Disodium ethylenediamine tetraacetate (EDTA; 2.0%) inhibited the formation of TBARS in 6M Gnd CI treated yolk, indicating a metal catalyzed reaction. Protein hydrolysis using 1% papain in the presence of added iron (FeC1₃) produced a significant increase (P<0.01) in conjugated dienes (233 nm) and trienes (270 nm). Increased lipid oxidation upon denaturation or hydrolysis of the protein moiety suggests that the ordered structure of lipid in the form of lipoprotein may partially account for the inherent oxidative stability of native yolk.     

Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at ?20 and ?30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of ?20 °C compared with samples stored at ?30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at ?20 than ?30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both ?20 and ?30 °C but was greater at ?20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at ?20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish. © 2002 Society of Chemical Industry     

EFFECTS OF DIFFERENT SALT CONTENTS ON SOME QUALITY CHARACTERISTICS DURING PROCESSING OF DRY‐CURED TURKISH PASTIRMA

ABSTRACT

This study examined the effects of different salt contents (3, 6 and 9%) during process stages on physicochemical, lipid oxidation and microbial quality of a dry‐cured meat product, past?rma, throughout 21 days of processing. Significant changes in moisture content, NaCl content, pH and water activity (a_w) were observed in past?rma after the third drying and pasting stages. There were significant decreases (P < 0.05) in objective color characteristics (L*, a* and b*) between raw material and final product for all past?rma samples. However, no significant effect of salt level (P > 0.05) was detected on L* and a*. Salt level significantly (P < 0.05) affected thiobarbituric acid‐reactive substances (TBARS) formation, which was lower in low‐salt past?rma samples, while the combination of salting, drying and pressing stages increased TBARS values in high‐salt past?rma samples. Higher salt content (6% and 9%) and last drying resulted in reduction of microbial count.

PRACTICAL APPLICATIONS

Salt (NaCl) is an important agent in inhibiting microbial growth, reducing water activity and imparting a salty taste to dry‐cured meat products such as ham and past?rma. Salt content in past?rma varies from 5% to 10% in the final product and has an impact on product quality parameters. The effects of different NaCl contents (3, 6 and 9%) and processing stages on pH, water activity (a_w), color parameters, lipid oxidation and microbial count were studied during processing of past?rma. Low‐salt concentration had some negative impacts on past?rma characteristics, giving high a_w, pH and microbial count, but low Thiobarbituric acid‐reactive substances value and NaCl content. Drying, pressing and pasting with çemen mixture during past?rma processing had a positive impact on reduction of moisture, a_w and microbial count.

     

The effect of natural antioxidants on haemoglobin-mediated lipid oxidation during enzymatic hydrolysis of cod protein

Heating and changes in pH often practised during fish protein hydrolysis can cause lipid oxidation. The effect of natural antioxidants towards haemoglobin-mediated lipid oxidation during enzymatic hydrolysis of cod proteins was investigated. Different variants of a washed cod model system, containing different combinations of haemoglobin and natural antioxidants (l-ascorbic acid and Fuscus vesiculosus extract), were hydrolysed using Protease P “Amano” 6 at pH 8 and 36 °C to achieve 20% degree of hydrolysis. Lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) were analysed periodically during the hydrolysis process. The in vitro antioxidant activity of the final products was investigated. Results indicate that oxidation can develop rapidly during hydrolysis and antioxidant strategies are preferable to produce good quality products. Oxidation products did not have an impact on the in vitro antioxidant activity of the hydrolysates. The natural antioxidants inhibited oxidation during hydrolysis and contributed to the antioxidant activity of the final product.     

The effect of α-tocopherol and butylated hydroxyanisole on the colour properties and lipid oxidation of kavurma, a cooked meat product

Kavurma is a cooked meat product and is consumed sliced. The amount of animal fat in kavurma (30-40%) is higher than in other meat products; therefore, lipid oxidation and colour defects are a major problem during storage and in the market place. To preserve the quality characteristics of kavurma in markets antioxidants must be added and the product must be packaged and stored at low temperature. In this study, the effects of α-tocopherol and butylated hydroxyanisole (BHA) levels on lipid oxidation and colour deterioration of sliced and vacuum-packaged kavurma were investigated. Kavurma was made from beef meat and melted beef fat in 5 groups: No-added antioxidant, 50mg/kg BHA, 100mg/kg BHA, 50mg/kg α-tocopherol and 100mg/kg α-tocopherol. The kavurma produced was sliced (3-4-cm thick) and vacuum packed and stored at 4°C for 300 days, and thiobarbituric acid reactive substance, pH, moisture, lightness, redness and yellowness values of sliced product were determined during storage. The use of antioxidants in kavurma production caused a significant (P<0.01) decrease in the thiobarbituric acid reactive substances (TBARS) values. The lipid oxidative stability effect of the antioxidants was in following order: 100mg/kg BHA>100mg/kg α-tocopherol>50mg/kg BHA=50mg/kg α-tocopherol>no-added antioxidant group. Also, TBARS values did not differ significantly (P>0.05) between 0 and 300 days in the 100mg/kg BHA and 100mg/kg α-tocopherol groups. In addition, the no-added antioxidant group had lower lightness and yellowness values than all the antioxidant groups. Sliced and vacuum-packaged kavurma with added antioxidant showed greater colour and lipid oxidative stability during storage than kavurma to which no antioxidant was added.     

Characterization of lipids and antioxidant capacity of novel nutraceutical egg products developed with omega‐3‐rich oils

BACKGROUND: Cardiovascular disease has had an unquestioned status of the number one cause of death in the US since 1921. Omega‐3 polyunsaturated fatty acids (ω‐3 PUFAs) have cardio‐protective benefits. However, egg is typically a poor source of ω‐3 PUFAs and, in general, the American diet is low in these cardio‐protective fatty acids. Novel, nutritionally enhanced egg products were developed by substituting yolk with ω‐3 PUFA‐rich flaxseed, menhaden, algae, or krill oil. Experimental egg products matched composition of hen egg (whole egg). The experimental egg products, mixed whole egg, and a liquid egg product (Egg Beaters^?) were microwave‐cooked and compared. RESULTS: Although fat, protein, and moisture contents of experimental egg products matched (P > 0.05) mixed whole egg, experimental egg products had more (P < 0.05) ω‐3 PUFAs, lower (P < 0.05) ω‐6/ω‐3 ratio, and depending on oil added, a higher (P < 0.05) unsaturated/saturated fatty acids ratio compared to mixed whole egg. Triglycerides were the main lipid class in all experimental egg products except those developed with krill oil, which had even more phospholipids than mixed whole egg. Analysis of thiobarbituric acid reactive substances showed that lipid oxidation of experimental egg products was lower (P < 0.05) or similar (P > 0.05) to mixed whole egg, except for experimental egg products with krill oil. However, peroxide value showed that all egg samples had minimal oxidation. Experimental egg products developed with menhaden or flaxseed oil had the highest (P < 0.05) concentration of the antioxidant, ethyoxquin compared to all other egg samples. However, experimental egg products with krill oil likely contained a natural antioxidant, astaxanthin. CONCLUSION: This study demonstrated an alternative approach to developing novel, nutraceutical egg products. Instead of dietary modification of chicken feed, yolk substitution with ω‐3 PUFAs oils resulted in enhancement of ω‐3 PUFAs beyond levels possible to achieve by modifying chicken feed. Copyright © 2011 Society of Chemical Industry     

Oxidative stability of soybean oil in oleosomes as affected by pH and iron

The oxidative stability of oil in soybean oleosomes, isolated using the Enzyme-Assisted Aqueous Extraction Process (EAEP), was evaluated. The effects of ferric chloride, at two concentration levels (100 and 500 μM), on lipid oxidation, was examined under pH 2 and 7. The peroxide value (PV) and thiobarbituric acid-reactive substance (TBARS) value of oil, in oleosome suspensions stored at 60 °C, were measured over a 12 day period. The presence of ferric chloride significantly (P < 0.05) affected the oxidative stability of oil in the isolated oleosome, as measured by the PV and TBARS. Greater lipid oxidation occurred under an acidic pH. In the pH 7 samples, the positively charged transition metals were strongly attracted to the negatively charged droplets. However, the low ζ-potential and the high creaming rate at this pH, may have limited the oxidation. Freezing, freeze–drying or heating of oleosomes have an insignificant impact on the oxidative stability of oil in isolated soybean oleosomes. Manufacturers should be cautious when adding oleosomes as ingredients in food systems containing transition metal ions.