Introduction
Lupin is a legume and classified as a non- starch seed that has high amounts of protein and low oil content. There are different species of lupin and the type that is used for food purposes is known as Lupinus angustifolius or sweet Australian (Duranti et al. 2008). Proteins are normally used as food additives since they contribute to sensory attributes and improve the stability of different food products (Rodriguez-ambriz et al. 2005).
Proteins from animal source such as whey protein isolate (Perez et al. 2009) and egg yolk which have good emulsifying properties are used in many food applications (Daimer and Kulozik 2009). However, the high cost that is associated with animal base protein led to the use of alternative sources such as lupin protein isolate and because they have an excellent emulsifying and foaming properties (Raymundo et al. 2002). Lupin protein isolate are used in a wide range of food applications including the preparation of mayonnaise (Rosenthal 1999).
Objective
The aim of this study is to examine the use of lupin protein isolate in producing vegetable based mayonnaise at different concentration levels.
Lupin proteins help to produce foam and are used as a vegetable alternative to egg-white foams in food products. One such product that requires large numbers of eggs for foam production include mayonnaise, which is an appetizing food consumed for its unique mouth feel and texture.
Lupin protein isolates are used at varying levels to indicate the effects of varying concentrations on the end product, i.e. mayonnaise. Vegetable based mayonnaise is normally prepared with egg whites. In this study, we have used lupin protein isolates to prepare mayonnaise, but the levels of the concentration of the protein molecules vary.
Our objective is to analyze the difference in the end results of the mayonnaise produced, for the texture, and the droplet size. We will see how, if any, the varying levels of lupin content in the preparation of the mixtures affect the results obtained, and then analyze the effects observed.
The importance of conducting this study would be to distinguish the effects of lupin protein isolates concentration on proteins. On achieving a result, we can recommend mayonnaise manufacturers to use isolates of lupin proteins to enhance their productions, if they are interested. It has health benefits for which it can be increasingly used in food products today (Sweetingham).
Methodology
Equipment
- Centrifuge machine
- Test tubes
- Graduated cylinder
- Pipets
- Balance
- Filtration devices
Reagents
- Lupin protein in different concentration
- Xanthan as thickening agent
- Flour sample
- Distilled water
- NaoH (0.1M)
- HCL ((0.1)
Protein extraction process
The flour sample, however, is dissolved in distilled water (10% w/v) for about 30 minutes and a concentration of 0.1 M of NaOH is included to correct the PH to 9 and then stirred for one hour followed by centrifugation at 3000 rpm for 20 minutes. The supernatant was acidified by using 1M HCl to adjust the PH to 4.5 for protein precipitation. The precipitated protein was separated by centrifuging at 3000 rpm for 20 minutes (Rodriguez-ambriz et al. 2005). The precipitated protein is freeze dried and stored at -20 C.
The formulation process
The protein that was extracted is mixed with a thickening agent such as xanthan gum in a distilled water for 30 minutes at 25 C at PH values between 6.0 – 6.5 and then a vegetable oil is included. All the three components are blend together in a homogenizer and by using different concentration of protein (2-7%), xanthan (0-0.49%) and vegetable oil such as sun flower (25-60%) ( Raymundo et al. 2002). The composition is then evaluated at different levels through texture, droplet size,. Droplet size distribution is measured by laser light-scattering experiments. The texture is evaluated by viscosity through the use of viscometer. However, commercial mayonnaise is used as a standard.
This same procedure is repeated with different PH, different lupin protein concentration, xanthan and vegetable oil.
The independent variables that are evaluated are Protein, thickener, vegetable oil, PH and salt concentration, while the dependent variables that are predicted are texture, oil droplet size.
With different concentrations of protein, vegetable oil, thickening agent and PH levels different oil droplet size and texture can be evaluated.
Literature review
There are many studies investigated the functional properties of lupin protein isolate in a wide range of food products involving mayonnaise.
Lupin protein has great nutritious significance and functionality which is very helpful for the formation and stabilization of food emulsions e.g. dough, frankfurters (Pozani, 2001). There are a lot of milk products like cream liqueurs, coffee whiteners , ice cream, whipped Toppings etc. such milk products along with other additives like polysaccharides help in formation and stabilization of texture and shelf life of nutritional colloid dispersions. The dynamic nutritional elements of such processing milk products are characterized with adsorption rate and viscoelastic, playing a vital role in emulsion of foaming foods (Patino, et al, 2009).
In the modern age, there is a great demand of the functional lupid protein, having good solubility and emulsifying characteristics. Lupin proteins are obtained from hexane deoiled lupin, comprising the high molecular weight proteins, conglutin (compound of alkaline extraction and acid precipitation). Lupin protein extractions are high-quality protein isolates, pertaining to exclusive emulsification, foaming properties and salt tolerance (Knauf, et al, 2001).
For the assessment of functionality of lupid protein, the adults rats are fed with egg albumin-based diets including lupin protein from Lupinus albus or casein (50 g/kg), a cholesterol-cholate mixture, supplements of (hypercholesterolaemic) or not (normolipaemic). Lupin proteins, containing lipids in plasma lipoproteins and hepatic mRNA are playing significant role in lipid metabolism (Stangl et al, 2008). Lupid protein plays the significant role in cholesterol and bile acid metabolism. According to the modern research & study plays a hypotriacylglycerolaemic action by regulating the fatty acid synthesis genes with low or high rates which are entirely hydrolysis process (Stangl et al, 2008).
The lupin processed proteins are very important nutritional ingredient in the food industry for manufacturing of milk or dairy products. Lupin protein, emulsion stabilizer plays a role of binder which is supportive in blending fat or water or some other protein isolates (Method to produce lupin protein-based dairy substitutes, 2009). Lupin proteins are very assistive agent to protect food products, pre-cooked or cooked ones for long time without spoiling them.
Animal based mayonnaise which is also known as commercial mayonnaise is normally derived from egg yolk and due to the high cost that is linked to this type, led to the use of alternative sources (Raymundo et al. 2002). One of the recent and emerging alternative sources a protein extracted from lupin that can be utilized as a main substance in preparing mayonnaise because it has excellent emulsifying properties and the capacity to produce highly stabled O/W emulsion. As a result, the texture and flavor are improved (Raymundo et al. 2002). Protein isolate also contribute in the formation of smaller oil droplet size improving the stability of emulsions and increasing the shelf life (Rosenthal 1999).
However, Pozan, Doxastakis and Kisseoglou (2001) point out that emulsifying property of lupin protein isolate could be improved by heat treatment as a result of ‘molecular unfolding’ and improved surface interfacial tension characteristic. The researchers concluded that the functionality of lupin protein isolate including emulsion stability can be increased significantly through heat treatment.
A study was conducted by Raymundo et al. (2002) on the use of lupin protein to produce mayonnaise and its ability to produce stable emulsion that has similar characteristic properties as the commercial mayonnaise. The researchers blend certain amounts of protein isolate, xanthan gum and sunflower oil 2% 0.49% and 60% respectively after adjusting the PH to 6.0 under defined condition. To induce mayonnaise nearly matching the properties of commercial product the protein was not thermally denatured and it was in its native state. The researchers concluded that higher concentration of protein, xanthan gum and oil resulted in better viscosity, firmness, and smaller oil droplet size.
A research study conducted by Pozani, et.al showed the foaming and emulsifying properties of lupin seed protein isolate (LSPI). This was done by the addition of dithiothretol (DTT), and by heating process. Both the heat treatment and addition of DTT showed emulsion stability compared to creaming. For the conduction of the experiment, aqueous solutions of LSPI which had 2% of protein were prepared in a phosphate buffer of pH 7.
After treatment with heat or DTT, 100ml of each solution was mixed with a mixer. When the foams were made, they were measured in measuring cylinders. The results showed a difference in the foaming according to the structural differences of the molecules on treatment of heat, or disulphide bond reduction. It was also seen that both of these conditions resulted in better foaming and emulsifying properties of the foams achieved.
Another study showed the emulsification process of mayonnaise in relation to droplet size. The size of the droplets determines the amount of oil that can be emulsified, and it has been shown that a wider range of droplets can emulsify a larger amount of oil. The droplet sizes can be varied by controlling the emulsification process. In the first step of the process, oil droplets of 20-100 |um are roughly dispersed in a slow mixing process. This is followed by a finely mixing process for the emulsification to take place. The rate of shearing of the machines would affect the emulsification; the more vigorous the breakup process, the better the results obtained.
One study by Kulozik and Daimer (2008), showed the emulsifying properties of eggs, by the use of egg yolks. The function of egg yolks depends very much on the pH and salt concentrations of the materials used with the eggs for emulsification. In this study, four different conditions were employed, ph 4 of commercial dressings is simulated, pH 6.5 is the pH of untreated egg yolks. Two concentrations of NaCl were also used, in their native and disrupted forms. The results of this study showed that the emulsifying properties differed due to the structural changes in the yolk granules, and not because of the treatment with the lyso-phospholipids.
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