CHAPTER THREE
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
3.2.1 PREPARATION
OF MILK
3.2.1.1 PREPARATION
OF COCONUT MILK
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.
3.2.1.1
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.
3.2.1.1.1
YOGURT PREPARATION
EXPERIMENTAL TREATMENTS
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
3.2.1.2
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.
3.3 ANALYSIS
OF SAMPLE
3.3.1
PHYSICO- CHEMICAL ANALYSIS
3.3.1.1
pH
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).
3.3.1.2 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
3.3.1.3 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
3.2.1.3
TOTAL SOLUBILITY (oBRIX)
The total sugar (oBrix) will be determined
using Refractometer method. The
refractive index of the yogurt will be determined at 200c
3.2.1.4
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
3.2.1.5
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.
3.2.1.6
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.
3.3.1.9 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
CHARACTERISTICS
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).
3.6 STATISTICAL ANALYSIS
All data
will be subjected to analysis of variance (ANOVA) to determine any significant
difference at 5% level (LSD) using Iwe, (2002) method.
REFERENCES
Adams, M.R., and Moss M.O. (1999). Food microbiology.S
The Roray Society of Chemistry Thomas Graham House, Sceince park, Cambridge.
Adejuyitan, J.A., Otunota E.T., Akende E.A., Bolarinwa
I.F., and Oladokun F.M (2009). Some physiochemical properties of flour obtained
form formations of tiger nut (Cypenus esculentus) sources form a market in
Ogbomoso, Nigeria. Afr. Journal of Food
science. 3:51-55.
Anderson, J. W., Smith B.M., and Custafon N.J. (1994).
Health benefit and practical aspects of high fibre diets. Am. J. clin. Nutr.
59:1242-1247.
Anu Chacko, Hari Muraleedhara and Sastry P.S (2010)
Effect of storage conditions on the microbial quality of fermented foods. World applied sciences Journal 9(12):1365-1369.
Barnes H. A., Hutton, J. F., Walters, K. (1989).
An Introduction to Rheology. Elsevier Science B.V.,
Netherlands.
Belewu, M.A. and Abodurin. O.A. (2008). Preparation of
kuunu from unexpected rich food sources, tigernut (Cyperus esculentus). Pake.J.
Nutr., 7:109-111.
Belewu, M.A., and Belewu K.Y. (2007). Comparative
physic – coconut milk sources. Int J. agric biof. 5: 785-787.
Belewu, M.A., Belewu K.Y., and Bamidele R.A. (2010).
Cyper-coconut yoghurt: preparation, composition and organoleptie qualities.
Partisan Journal of food science and
technology 1(1): 010-072.
Beniwal, R.S., Vincent C.A.,Lenot., Sudhir N., Thomas
F.I; Rauf A.C and Usman A.A; (2003)”A Randomized trial of yogurt for prevention
of Antibiotic- associated Diarrhea”, Digestive Diseases and science
48:10:2077-2082 (October, 2003) doi:10.1023/A:1026/55 328638
Boume, M. C. (1982). Food Texture and Viscosity:
Concept and Measurement. Academic Press, Inc., USA.
Brainy dictionary (2005). Online www- brainy dictionary.
com/milk.190115
David B. Fankhauser, (2003) yogurt making illustrated
by professor of Biology and Chemistry U.C. Clermont collage Batavia OH 45/03.
Ekeanyanwu, R.C., Obioma N., and Ononogbu I.C.(2010) The
photochemical effects of Nigerian tiger nut (Cyperus eseulentus L)Tuber.
Pakisten journal of nutrition (7):709- 715.
Elson, M and Hass, M.D (2005). Dairy products online www. health. net /Scr Lartich asp?
Ernest, R.V.(1996) Elementary food science: 4thEdition.
International Thomason publishing USA.
Geankoplis, J.
C. (1993). Transport Processes and Unit Operations. Prentice-Hall
International, Inc., USA.
Ghanson, M.A.(2008). The use of tiger nut (Cyperus
esculentus), cow milk, and their composite as substrates for yogurt
production. HND Dissertation, Cape coast
polytechnic, Cape coats, Ghana.
Helferich, W. and
Westhoff D., (1980). Yogurt: All About It.
Herh, P. K. W., Cob, S. M., Roye, N. and Hedman K.
(2000), Rheology of Foods: New techniques, capabilities, and Instruments. www.astrheosystems
.com (07/12/05)
Ihekoonye, A, and Ngoody P.O. (1985). Integrated food science and technology for
the Tropics Macmillan Publishers Ltd
Kay, D.E. (1987) Roots
Crops: crop and product Digest No2. 2nd ed. Tropical development and research institute.
Kinsella, J. E. (1976), Functional properties of
protein foods; A survey, Critical Review in Food Science and Nutrition 228:
23 0-234.
Kolars, J.C. (1984) yogurt an autodigestiny source of
lactose. N. Engl. J med; 310:1-3-
Kosikowski F.V. (1982), Cheese and fermented milk
foods, published by Kosikowski F.V. and Associates, New York, pp. 1-711.
Lewis, M. J. (1987). Physical properties of Food and
Food processing systems. Chi Chester Ellis Horwood Ltd. Pp108-135
Manohar, R. S., Manohart, B., Rao, P. H. 1998.
Rheological Characterization of Wheat Porridge (cooked dalia), a Semi-liquid
Breakfast Food. Journal of Cereal Science. 27: 103-108.
Mattinez, V. (2003). Scientific analysis of effects of
tiger-nut on Heart diseases and Reluled Aspects. Tiger-nut and Reluled Aspects
tiger-nut and Health, pp. 1-2.
Moore, B. (2004). Yogurt. The Austratian Oxford
Dictionary 2nd ed. Oxford university press, London.
Nam Sun Wang, (2008). Yogurt fermentation with
lactobacillus cultures. Department of Chemical and Bimolecular engineering
university of manyland college park. (MD 20742-2111 ENCH 485.
Nwaoguikpe, R.N. (2010). The photochemical, proximate
and amino acid compositions of the
extracts of two varieties of tiger-nut (Cyperus esculentus) and their
effects on sickle cell. Hemoglobin polymerization. Journal of medicine and medical sciences. 1(11): 543-549.
Nwokolo, E. (1985). Nutritive quality of seeds of
African Breadfruit (Treeculia africanum). Tropical science.
Odoemelan, S.A. (2003). Chemical Composition and
functional properties of conophernaut flour (retracarpridium conophorium). International Journal of food science and Technology. 38:729-734.
Okafor, J.N.C., Mord J.I. Ozuma A.U., Solomon M.H.,
characteriszation of contaminants in tiger-nut (yellow variety). Proceedings of
27th annual. Nigerian Institute of food science and technology
(NIFST) conference, Oct. 13-17, Nigeria, pp 210-211.
Oledele, A.K. and Aina J.O. (2007). Chemical composition
and functional properties of flour produced from two varieties of tigernut (Cyperus
esculentus). African Journal of
Biotechnology, 6(21): 2473-2476.
Pelegrine, D. H., Silva, F. C., Gasparetto C. A. 2002.
Rheological Behavior of Pineapple and Mango Pulps. Lebensm.-Wiss. u-Technol.
35: 645-648.
Rosenthal, Sylvia Dworsky, (1978). Fresh food.
Bookthrift co.p. 157. http.//books. Google.com/booksid =6zwvaaaayaaj.Retrieved
11 AUGUST, 2009.
Snyder H.E. and Kwon T.W., (1987). Soybean
Utilization. AVI Connecticut New York. Pp 163 184
Sopade, P.A. and Kassum, A.L. (1992). Rheological
characteristics of Nigerian liquid and semi-liquid food. Kunuzaki and
knnungyada. Nigerian food Journal 10:23-33.
Steffe, J.F. 1996. Rheological Methods in Food Process
Engineering. Freeman Press, USA.
Van Wazer, J.R., Lyons, J.W. 1966. Viscosity and Flow
Measurement. John Wiley & Sons, Inc., USA.
Wikipedia, (2005). On line
@www.cu.wikipedi.org/pasteurization 1208-11
Worlow R. W., 1992. Rheological Techniques. Ellis
Horwood Limited, England.