Thien Trung Le

Effect of washing conditions on the recovery of milk fat globule membrane proteins during the isolation of milk fat globule membrane from milk

During the isolation of milk fat globule membrane (MFGM) from milk, washing is considered the most critical stage in which loss of MFGM components occurs. In this study, using a cream separator, the influence of washing on the recovery of MFGM proteins was investigated. The residue of non-MFGM proteins in the MFGM material obtained after washing was quantitatively determined using densitometric analysis of one-dimensional sodium dodecyl sulfate-PAGE after silver staining of the gel. Using deionized water as the washing solution did not increase the loss of MFGM proteins compared with other common salt solutions in terms of recovery of MFGM proteins and contamination with non-MFGM proteins. The increase in wash temperature from 38 to 46 degrees C did not show a significant decrease in yield of MFGM proteins because of variation between the experimental replicates. Coalescence of fat globules occurs during isolation. To increase MFGM purity while maintaining a high MFGM protein recovery, using larger volumes of wash solution is more advisable rather than increasing the number of washings from 2 to 3.

Improved solvent extraction procedure and high-performance liquid chromatography-evaporative light-scattering detector method for analysis of polar lipids from dairy materials

A normal-phase high-performance liquid chromatography-evaporative light-scattering detector method employing dichloromethane, methanol, and acetic acid/triethylamine buffer as the mobile phase was developed for analysis of polar lipids (PLs). This method was applicable for analysis of PLs from both dairy materials and soy lecithin. All of the PLs of interest such as glycolipids, phospholipids, and sphingomyelin were well separated with a total run time of 22.5 min and without necessitating the removal of neutral lipids beforehand. Peak retention times were stable, and the method was reproducible. In this study, a modified method of using solvents for extraction of PLs from dairy matrices was also investigated. The modified method offered higher extraction efficiency, consumed less time, and in some cases saved solvent use.

Chapter 5:Membrane Separations in Food Processing

The continuous search for innovative food processing methods has led to numerous breakthroughs in membrane technology. This chapter covers the most basic concepts of membrane technology such as membrane materials, module configurations, and operation up to the most complex concepts involved in four pressure-driven membrane processes namely MF, UF, NF and RO.One formidable obstacle toward wide acceptance of membrane technology is the problem on concentration polarization and membrane fouling. This chapter describes both and discusses their different mechanisms and the conditions which cause each mechanism. An extensive discussion on the state-of-the-art techniques to enhance membrane process performance is also presented. This includes optimization of operational conditions, pre-treatment of feeds, modification of membrane modules, flow manipulation and application of external body forces such as ultrasound and electric field. Different techniques and approaches in membrane cleaning are also discussed. The chapter also details the technologys potential applications in the food industry such as in the processing of milk, beer, wine, juice, sugar, soy products, and other food products. It presents a comparison of the technological and economic advantages and disadvantages of membrane processes to that of traditional food processing methods. Some of its better known advantages are the production of food which has better technological and nutritional functionalities, efficient use of material and resources, and reduced negative impacts to the environment.With the numerous developments and studies done and still being done on the system, one can only look forward for more widespread adaptation of membrane processes in the industry.

Individual Phospholipid Classes from Iberian Pig Meat As Affected by Diet

The main objectives of this study were to (1) determine the individual phospholipid (PL) classes content of fresh meat from Iberian pigs and their respective fatty acid and dimethylacetal composition and (2) assess the effect of different diets (acorn and grass vs oleic acid enriched concentrates) on these lipid species. First, it was found that phosphatidylcholine was the major PL, followed by phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol in decreasing order. Each PL class showed a different lipid profile. Second, the feeding regimen influenced the quantity and the fatty composition of the individual PL classes. Meat from pigs fattened with high oleic acid concentrates had higher amounts of most phospholipid classes and polyunsaturated fatty acids, which is an indication of lipid oxidation instability. Lastly, these differences in PL species and fatty acid composition could be used to differentiate meats from Iberian pigs with different feeding regimens.

Development of an Offline Bidimensional High-Performance Liquid Chromatography Method for Analysis of Stereospecific Triacylglycerols in Cocoa Butter Equivalents

Acyl migration is a serious problem in enzymatic modification of fats and oils, particularly in production of cocoa butter equivalent (CBE) through enzymatic acidolysis reaction, which leads to the formation of non-symmetrical triacylglycerols (TAGs) from symmetrical TAGs. Non-symmetrical TAGs may affect the physical properties of final products and are therefore often undesired. Consequently, an accurate method is needed to determine positional isomer TAGs during the production of CBE. A bidimentional high-performance liquid chromatography (HPLC) method with combination of non-aqueous reversed-phase HPLC and silver ion HPLC joining with an evaporative light scattering detector was successfully developed for the analysis of stereospecific TAGs. The best separation of positional isomer standards was obtained with a heptane/acetone mobile-phase gradient at 25 °C and 1 mL/min. The developed method was then used in multidimensional determination of the TAG positional isomers in fat and oil blends and successfully identified the TAGs and possible isomers in enzymatically acidolyzed CBE.

Muscle individual phospholipid classes throughout the processing of dry-cured ham: influence of pre-cure freezing.

This paper aims to study the profile of phospholipid (PL) classes of Iberian ham throughout its processing and the changes it underwent due to the influence of the pre-cure freezing treatment. The general profile of each PL class did not vary during the ripening stage. Phosphatidylcholine (PC) showed the highest proportion, followed by phosphatidyletanolamine (PE) and phosphatidylserine (PS) and phosphatidylinositol (PI) being the minor PL. The four PL classes were highly hydrolysed during the salting stage and their degradation continued during the rest of the processing. Pre-cure freezing of Iberian ham influenced the levels of the four PL classes at the initial stage, all of them being higher in refrigerated (R) than in pre-cure frozen (F) hams. Moreover, the pattern of hydrolysis was not the same in these two groups.

Milk and Dairy Polar Lipids: Occurrence, Purification, and Nutritional and Technological Properties

Publisher Summary Cows milk contains 12.8–40 mg/L of total Polar Lipids (PLs), which is equivalent to 0.32–1.0% of the total lipids of milk. A major part of PLs in milk is the membrane surrounding fat globules, which is called the Milk Fat Globule Membrane (MFGM). In the dairy industry, processing techniques, such as churning cream into butter or homogenizing (phase conversion) the concentrated cream into butter oil break the fat globules and the resulting MFGM fragments are preferentially distributed to aqueous phases, such as buttermilk and butter serum. Technologies are available for isolation of MFGM fragments and for further purification to obtain PL concentrate from the byproducts. Recently, milk PLs have gained attention because of the beneficial health properties they possess. In addition, PLs are amphiphilic molecules that can be used as emulsifiers for food product development. This chapter discusses the occurrence, composition, and factors influencing composition of PLs in milk, explains the distribution of MFGM and PLs during dairy processing, and this helps determine which processing-derived streams/fractions can serve as a good sources for isolation of MFGM and purification of PLs. It also presents isolation and purification techniques, reviews nutraceutical and technological properties of PLs, and discusses the possible applications of MFGM material and PL concentrate. The chapter elucidates the possibilities of obtaining MFGM material and PL concentrate from dairy processing–derived streams and the potential uses of such ingredients for development of functional foods and nutraceuticals.

CHAPTER 4:Analysis of Non-extractable Polyphenols (NEPP)

Non-extractable polyphenols (NEPP) are polyphenols remaining in the solid residues after aqueous–organic extraction, which are mostly proanthocyanidins, hydrolysable tannins and phenolic acids bound to the food matrix. The aim of this chapter is to provide an overview on current extraction and analysis methods of NEPP. Advantages and drawbacks of each method will be discussed.

Chapter 11:Membrane Separations

Membrane technology plays an important role in food processing. This technique not only helps reduce the use of solvents in separating food components (milk fat, milk proteins, polyphenolic compounds, etc.) but also improves the quality and stability of many food products (fruit juice, wine and beer, etc.). An overview of membrane technology (definition, classification, principles and operating conditions) and its application in food processing is presented in this chapter. In this new edition, the latest information in many fields has been updated, including new membrane materials, membrane performance enhancement and new applications in food processing introduced during the past decade.