29-07-2011

Meeting 29 July 2011 Was held on 29th of July’ 2011 and was called by Paul Kajda. Thestart time of the meeting was at 2.00pm and the end time was at 3.00pm for the shelf lifedetermination of the samosas.
 * Agenda: ** The meeting was called in order to discuss about theshelf life testing of the samosas.
 * Points to be discussed: **
 * The main points to be discussed in the meeting were the experiments design **

The characteristicwhich is going to be tested in the samosas Accelerated shelf life test is lipidoxidation, because it is the main cause of off-flavors and aromas that may becreated during storage. The sunflower oil will be extracted from the sample byusing the Soxhlet method and then the peroxide value of each oil sample will bedetermined. Peroxide value is used as a method ofassessing rancidity reactions in oil during storage. It is useful in order todetermine the extend of deterioration reactions which will produce off-flavorsand aromas in the frozen product. The oil, which is contained in the samosas,starts to autoxidating during storage. Due to the fact that sunflower oilcontains a high degree of monounsaturated and polyunsaturated fatty acids ismore susceptible for autoxidation. Peroxide value is a measurement of theautoxidation of oils. The autoxidation reaction is a free radical reaction withoxygen and the products of that reaction are hydroperoxides, which can breakdown and form low-molecular compounds such as aldehydes, free fatty acids andketones. All these products cause autoxidative rancidity and the peroxide valueis used to measure the hydroperoxides in the product. In that way, peroxidevalue is a very useful measurement for the determination of shelf-life of afrozen product. The content of peroxides is expressed in milliequivalentsperoxidic oxygen per kg of sample. Fresh oil should have a peroxidevalue<10meq/kg. When the peroxide values are higher than 20 to 40 meq O2/kg,it is characterized as rancidity. The experiment designwhich will be conducted for measuring the peroxide value change in the samosasis described below: Six samples are keptat 60°C, 6 samples are kept at 4°C and 6 samples are kept at 40°C for 35 dayseach. On the first day of the experiment 2 samples from each temperature areused for oil extraction and on the next day of the experiments the oil whichhas been extracted is used for peroxide value determination. After thedetermination of the peroxide value of the first samples the team is going todetermine the gaps between the experiment days.

The experimentaldesign is described below: The oil is extractedfrom the samosa sample and then the oil sample is put into a Erlenmeyer flask.Acetic acid-chloroform solution is added and then is added KI solution anddistilled water. The method is based onthe measuring of the iodine which is produced by the reaction of peroxides withpotassium iodine and the solution gets a yellow color: KI + ROOH-> ROH + K0H + I2 After that step thesolution is titrated with sodium thiosulphate solution, almost until the yellow iodine colourdisappears: 2Na2S2O3 + I2-> Na2S4O6 + 2 NaI The acetic acid isadded in order to react with the base OH-which is formed by the hydrolysis of KOH. After the titration,sodium lauryl sulphate (SDS) is added and then starch indicator solution is added(blue color). The titration continues with constant agitation and thethiosulphate solution is added until the blue color disappears.

The calculation of theperoxide value is based on the formulation: Peroxide value (milliequivalents peroxide/1000gsample) = Sx M x 1000/sample,g Where, S = volume of titrant, mL of sample M= normality of sodium thiosulphate solution = 0.01M Recent researches have shown that as timepasses the peroxide value of sunflower oil increases. Furthermore, it isexpected that the peroxide value of the samples stored at 40°C and 60°C reachesits peak increase more quickly than the peroxide value at 4°C and in shortertime. The Arrhenius equationis used in order to describe the temperature dependence of peroxide production rate per day. The apparent zero-orderrate constants of peroxide formation (kPV)can be described as a function of temperature, lnkPV= f(T-1)between -18°C and 40°C. In that way: KPV = k0e (-Ea/RT), where kis the reaction rate constant; R is the molar gas constant (8.31J/K/mol); T isthe absolute temperature (K); Ea is the activation energy (J/mol);and k0 is the frequency factor. The assumption which is made inorder to apply the Arrhenius equation for shelf-life experiments is that exceptfor temperature, all the other factors should be constant. After theperoxide value measurement the shelf-life of the samosas will be determined.

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