Seed to seed variation of proteins of the yellow pea (Pisum sativum L.).

The existing variation among pea protein isolates' functionality limits their application in food formulations. The source and extent of variations among yellow pea protein profiles was assessed in 10 single seeds of two varieties with different size and weight. A new approach was developed to analyze proteins of yellow pea combining three analytical methods of size exclusion chromatography (SEC), reverse phase high performance liquid chromatography (RP-HPLC), and microfluidic SDS-PAGE, to achieve the highest separation resolution. A high variation of protein concentration was observed not only between varieties, but also among seeds of the same variety. Vicilin to legumin ratio was between 2.72-4.19, and 1.70-2.22 among the individual seeds of AC Agassiz and CDC Saffron varieties, respectively. V/L ratio was significantly different among the individual seeds for both varieties. The amount of some protein fractions/subunits were correlated with seeds' size and weight for AC Agassiz, while such correlations were not observed for CDC Saffron.

Identification of gluten-like proteins in selected pod bearing leguminous tree seeds.

The protein composition, molecular weight distribution, and rheological properties of honey locust, mesquite, Kentucky coffee tree, and carob seed germs were compared against wheat gluten. Polymeric and Osborne fractionation protocols were used to assess biochemical properties. Dynamic oscillatory shear tests were performed to evaluate protein functionality. All samples had similar ratios of protein fractions as well as high molecular weight disulfide linked proteins except for the Kentucky coffee tree germ proteins, which were found to have lower molecular weight proteins with little disulfide polymerization. Samples were rich in acidic and polar amino acids (glutamic acid and arginine,). Rheological analyses showed that vital wheat gluten had the most stable network, while Kentucky coffee seed proteins had the weakest. High molecular weight disulfide linked glutenous proteins are a common, but not universal feature of pod bearing leguminous trees.

Solid-phase micro extraction of food irradiation marker 2-dodecylcyclobutanone (2-DCB) from chicken jerky treated with glycerol.

The food irradiation marker, 2-dodecylcyclobutanone (2-DCB), assayed by SPME provides a fast and simple method to estimate the irradiation history of fat-containing food products. The SPME conditions were optimized to maximize the extraction of 2-DCB from chicken jerky treats (CJT) irradiated at low (5 kGy) and high (50 kGy) doses. The extracted 2-DCB was measured using GC-MS in selected ion mode (m/z 98, and 112). Water dilution (1:5) was needed to mobilize 2-DCB and allow partition to the headspace form the CJT matrix. Increasing the incubation temperature to 80 °C resulted in higher response. Spiking control jerky samples with 2-DCB from 10 to 150 ng/g CJT compared with spiking water revealed a significant food matrix effect. This method provides a fast, simple, and environmental friendly alternative for the existing solvent extraction methods.

Amino acids effects on heterocyclic amines formation and physicochemical properties in pan-fried beef patties.

The effects of surface application of amino acids on the formation of heterocyclic amines (HCAs) and meat quality properties were evaluated in pan-fried beef patties (230 °C/15 min). Tryptophan, lysine, leucine, and proline at three concentrations, 0.05%, 0.20%, and 0.50% (w/w), were tested. The meat crusts were analyzed for HCA content using liquid chromatography-tandem mass spectrometry. Results showed that surface application of all tested amino acids significantly reduced total HCA content (P < 0.05), and the interaction of amino acid type and concentration significantly affected (P < 0.05) both individual and total HCA formation. Tryptophan at 0.50% reduced total HCAs the most (0.92 ng/g, 93% inhibition), followed by 0.50% lysine (1.94 ng/g, 84% inhibition), while leucine (3.95 ng/g, 64% inhibition) and proline (4.71 ng/g, 56% inhibition) were less effective at 0.50%. In addition, applying amino acids to meat surface significantly influenced (P < 0.05) pH and surface color change of beef crusts; particularly, lysine at 0.20% and 0.50% increased pH and a* (redness) but reduced b* (yellowness), while tryptophan and leucine at 0.50% increased L* (whiteness). No significant effect was observed on cooking loss. Adding amino acids at 0.50% affected (P < 0.05) formation of aldehydes and pyrazines (as the key flavor compounds of fried beef). Overall, the results of this study suggested that adding amino acids to ground beef patties could effectively mitigate mutagenic HCA formation during cooking.

Determination of Heterocyclic Amines in Meat Matrices Using Enhanced Matrix Removal-Lipid Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

A simple, fast, and efficient method, "enhanced matrix removal of lipids" (EMR-lipid), was proposed, optimized, and validated for identifying five polar heterocyclic amines (HCAs) in meat samples that ranged from high-protein (beef and chicken) to high-fat (pork bacon) matrices. The protocol involves an initial solid-liquid phase extraction followed by a rapid dispersive solid-phase extraction using EMR-lipid sorbents and salting-out partitioning. Acetonitrile containing formic acid at two levels (1% and 2%) efficiently extracted HCAs from different meat matrices. Liquid chromatography-tandem mass spectrometry (MS/MS) with selective reaction monitoring mode was developed for qualitative and quantitative analysis. The highest MS/MS responses and better peak separation of analytes were achieved by adjusting mobile phases to pH 3.0 with instrumental detection limits between 0.01 and 0.05 ng/mL. Good linearity of standard curves was obtained in both pure solvents and postspiked meat extracts between 0.5 and 50.0 ng/mL. The validation results showed good precision, accuracy, and sensitivity for detecting HCAs in spiked meat samples. Satisfactory recoveries of four HCAs were achieved: 65% to 111% in beef, 71% to 106% in bacon, and 42% to 77% in chicken. Matrix effects were also assessed and showed less than -20% of ion suppression in bacon extract, while a medium to high signal suppression was observed in beef (-37% to -55%) and chicken (-28% to -52%). This optimized EMR-lipid method provides acceptable results and advantages for determining trace level HCAs in complex meat matrices.

Effect of ultrasonication, pH and heating on stability of apricot gum-lactoglobuline two layer nanoemulsions.

The objectives of this study were to evaluate the effect of apricot gum-lactoglobuline (AG/LgC) ratio, thermal treatment, sonication with different times and amplitudes and pH, on double layer sunflower oil in water emulsion stability. The emulsion stability was determined by the evaluation of emulsion performance indices including particle size, zeta potential, creaming and emulsion volume stability during 10 days of storage. Applying AG and LgC with the ratio of 12.5:1 AG:LgC, in order to obtain double layer oil in water emulsion, could result in a completely stable nano-emulsions during 10 days storage in room temperature. The ultrasound treatment significantly increased the emulsion stability. A 10min ultrasound treatment with the amplitude of 25% was the optimum conditions for ultra-sonication. The best temperature for thermal treatment and the best pH, in order to improve the emulsion's stability, was 50°C and 3, respectively.

Application and stability of natural antioxidants in edible oils in order to substitute synthetic additives.

Antioxidants are components which prevent auto-oxidation of oils and fats by giving their hydrogen to free radicals formed in the initiation and propagation stages of autoxidation. During the past two decades, a lot of researches using natural plants extract in edible oils have been carried out due to the trend to minimize or avoid the use of synthetic food additives. According to the most studies, there are various natural antioxidants which can be extracted from low cost resources, such as most parts of olive plant, green tea, sesame, medicinal plants, etc. One of the most important requirements for a suitable antioxidant in oils and fats is the thermal stability during heat processing. It has been shown that most of natural additives have more antioxidants activity and thermal stability than synthetic ones in different edible oils. In this review, recent advances in the application of natural antioxidants in the food industry will be covered.

The influence of cooking process on the microwave-assisted extraction of cottonseed oil.

Cooking process is one of the most energy and time consuming steps in the edible oil extraction factories. The main goal of this study was cottonseed oil extraction by microwave radiation and elimination of any heat treatment of cottonseeds before extraction. The effect of cooking process on the physicochemical properties of extracted oil from two varieties of cottonseed (Pak and Sahel) was evaluated by free fatty acid content, melting point, smoke point and refractive index. Our results didn't show any significant differences between cooked and uncooked samples (P > 0.05) regarding physicochemical characteristics. From GC analysis of extracted oils, it was found there is no significant difference in fatty acid composition of cooked, uncooked and control (conventional extraction) samples. The thermal stability (Rancimat) analysis of oil samples showed the cooking process could cause a slight increase in the stability of oils for both varieties (about 40 min). The cooking process also increased total extracted phenolic compounds and considerably decreased total gossypol content of the cottonseed oil; but the extraction efficiency didn't change considerably after elimination of the cooking process. It can be concluded that microwave rays can destroy the structure of oil cells during process and facilitate the oil extraction without any heat treatment before extraction.

Optimization of microwave-assisted extraction of cottonseed oil and evaluation of its oxidative stability and physicochemical properties.

Microwave assisted extraction (MAE) is a novel method, which can reduce the extraction time and solvent consumption. This study aimed to evaluate the influence of MAE on oxidative stability and physicochemical properties of cottonseed oil. We found that the optimum extraction conditions were: irradiation time 3.57 min; cottonseed moisture content 14% and cottonseed to solvent ratio 1:4, which resulted in an extraction efficiency of 32.6%, 46 ppm total phenolic content, 0.7% free fatty acids, peroxide value of 0.2 and 11.5 h of Rancimat oxidative stability at 110 °C. GC analysis for MAE cottonseed oil determined palmitic acid (23.6%), stearic acid (2.3%), oleic acid (15.6%) and linoleic acid (55.1%), which were not significant different (P>0.05) than conventionally-extracted (control) cottonseed oil. MAE oil samples from whole cottonseed (without dehulling) had the greatest long-term stability, more than oil samples containing BHT.