3.0                                                                   MATERIALS AND METHOD
3.1                   SOURCES OF SAMPLES
          Coconut, yellow variety of fresh tigernut and packaged whole milk powder will be purchased from a local market (meat market) in Abakaliki metropolis, Ebonyi state, Nigeria.  While the stouter culture will also be purchased from on supermarket in Abakaliki metropolis, Ebonyi, state Nigeria.  The lactose and sucrose will be purchased from Ogbete main market at Enugu, Enugu state, Nigeria:

3.2                   SAMPLE PREPARATION
      The coconut will be broken using small club the mealy part removed using a dull stainless stell knife.  The brown skin will be removed with a sharp knife and the meaty part without the brown skin will be thoroughly wash and grater using a grater. The grated coconut meaty part will be mixed with warm portable water in a bowl allow to stand for 10mins to extract the oil, aromatic compounds and the milk.  The extract will be filtered through a muslin cloth to separate the milk from the insoluble chaff to obtain a milk – white emuslsion with a sweet coconut flavour (Belewu, M. A., Belewu, K.Y and Bamidele, R.A, 2010).  The milk will be stored at  5oC Inside the refrigerator before use.                                         PREPARATION OF TIGER- NUT MILK
        The method of Belewu and Abodunin (2007) will be adopt.  The preparation of the tiger-nut milk will be done by picking out those foreign and bad nuts that could affect the taste and keeping quality of the milk.  The tiger-nut will be washed and rinsed with portable water.  One kg of tiger nut will be conditioned over night in laities of portable water to soften the fiber.  The total content will be blend several times with a blender.  The mash will be filtered through a mush in cloth to separate the milk from the insoluble chaff.  It will further stain to obtain a fine consistency and will be stored at 180c until use.      YOGURT PREPARATION
            Various yogurt samples will be prepared by combining two of the different milk source (3) together.
The experimental treatment will be shown in table (3)

Table (3)
T1 = 100% whole milk powder (control)
T2 =100% tiger nut milk yogurt
T3 = 100% tiger nut milk yogurt
T4 =30% tiger nut milk + 70% coconut milk yogurt
T5 =50% tiger nut milk + 50% coconut milk yogurt
T6 =70% tiger nut milk 30% coconut milk yogurt                                         PREPARATION OF VARIOUS BLENDS YOGURT
The method of Belewu et al; (2005) will be used.  The various milk sample mixture in table3 will be heated separately to a temperature of 850c for 15mins, then cool rapidly to a temperature of 430c.  Each of the treatment will be inoculated at this temperature with 2% of thou this starter culture (streptococcus thermophillus and lactobacillus bulgaricus).  After complete fermentation, 5g of sugar will be added to each of the treatment.  The stored yogurt will be stored in the refrigerator until for analysis.

        The pH value of the yogurt sample will be measured in a 50ml beaker at a temperature of 2o.c using a Digital flt meter (model 152k).            TOTAL TITRATABLE ACIDITY (TTA)
      The total titratable acidity of the yogurt sample will be determined as described by Morris (1999). 10ml of yogurt sample will be transferred to a proclaim dish with the aid of 10ml pipettle. The pipettle will be rinsed with 10ml of water and the rinse will be added to the dish 1ml of Phenolphthalein indicator solution will be added to the dish and titrated with 0.IN sodium hydroxide (NaoH) solution until a pink colour will be obtained. 
The titretable acidity (% lactic acid)=
Titer value x molarityx 0.09   x   100      
Volume of sample (ml)       1            TOTAL SOLIDS (TS)
      The total solids will be determined by (AOAC,1995) method.  4g of the sample will be weighed into a metal dish and keep in a water bath for 30mins and thereafter heated in an over at 1000c for 21/2 hours.  The sample will be cooled in a desicator for 30mins and weighed.  The sample will be reheated in the over for another one hour, cooled and reweighed.  This will be repeated until weight loss between successive weighing become.  Negligible (<0.5g).  the percent total solids will be calculated from the formular:
Ts% = Final weight of yogurt sample- weight of dish   x    100 
                            Weight of sample                                     1                                         TOTAL SOLUBILITY (oBRIX)

The total sugar (oBrix) will be determined using Refractometer method.  The refractive index of the yogurt will be determined at 200c                                         DETERMINATION OF ASH
      Ash will be determined as described by the AOAC,(1995) method.  About 2.og of the sample will be weighed into a crucible of known weight.  Crucible and content will be dried in an oven queenly until smoking cases and then at 5oooc to 5700c in a muffle furnace for about five hours until a white or gray ash will be gotten.  Using a crucible tong, the crucible will be transferred to a dessicator and allowed to cool.  The crucible and the ash will be reweighed (Wc).  The percentage ash content will be then calculated thus
        Ash (90) =Wc – Wa x 100
                        Wb – Wa     1
where Wa = weight of empty crucible
            Wb = weight of sample with crucible before ashing
             Wc = weight of sample with crucible after ashing                                         FAT CONTENT
         The fat will be determined by the Werner Schmidt’s method as described by Pearson, (1981).  About 10g of the yogurt sample will be weighed into an extraction tube and 10ml of concentrated HCL added.  The tube will be immersed in a water bath until the casein content (protein) is dissolved.
           The fat will be extracted by shaking with 30ml of diethyl ether into a weighted flask and 10ml of alcohol will be added to aid the separation in separating funnel.  The fat will be dried at 1000c, cooled and weighted.                                         PROTEIN DETERMINATION
      The protein will be determined using kjeldahi 
distillation method as described by AOAC, (1995) and a conversion factor of 6.25.a protein of the sample containing up to 0.04m will be weighed and transferred to Kjeldahi digestion flask.  About 5ml of concentrated H2S04 will be added and catalysts which will include about 2.0g of potassium sulphate, Na2S04 will be heated until the liquid becomes clear.  A portion of the sample will be converted to ammonic and also to ammonium sulphate (NH4 )2S04 during digestion.
      The digest will be diluted with distilled water and alkaline made using excess concentrated (50%) sodium hydroxide up to 75ml.
        The ammonia will be distilled into 2% boric acid (50ml) and the condenser removed as well as the delivery tube after washing into the receiver.
        The distillate will be titrated with 0.l N H2S04 to purplish- gray end point.  The percentage Nitrogen (%N) will be calculated thus:
Nitrogen(%)  =          Titrevalue x 0.IN x 0.014           x      100
                                                Weight of sample in grams                  1
% crude protein  = %N  x 6.25

3/3/18 Moisture Content (Determination)
      The moisture content will be determined using the vacuum oven method. The moisture cans will be washed and dried in the oven and weighed using analytical weighing balance. Two grams of the sample will be put into previously weighed moisture can. The sample in the moisture can will be put into the Oven at 7o0c for 2 hours. The sample will be removed and place in the desecrator to cool and weighed. The sample will be reheated and cooled intermittently until content mass swill be obtain. The difference in mass as percent moisture will be calculated as the % moisture content.            CARBOHYDRATE (CHO)
      The carbohydrate content o the yogurt will be determined by difference according to AOAC (1995) as it will be given as carbohydrate by difference i.e the percentage of moisture, protein, fat, and ash substrate from 100
(CHO (%)  =  [100 – (M.C + protein + fat + Ash)]
Where MC = moisture content.
3.4 Viscosity measurement
      The viscosity readings of each yogurt will be measured using a digital display viscometer (model NDJ-85) taken at constant time intervals with progressively increasing shear rate 96-60/mins). Viscosity values will be obtained by multiplying viscosity readings with appropriate factor.
      Flow curves will be platted with the values obtained. Form equation3, log log plot of Uapp against y, a straight line of slope (n-1) 3.5       SENSORY ANALYSIS
      A twenty-member, semi-trained panel will be used to evaluate the various sensory parameters (flavour, appearance/colour, taste/sourness, texture/consistency and overall acceptability). The score will be base on a hedonic scale range form 9 representing “like extremely” to1 representing “dislike extremely” (Iwe, 2002).
      All data will be subjected to analysis of variance (ANOVA) to determine any significant difference at 5% level (LSD) using Iwe, (2002) method.

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