Specific Aim 1: Determine the acceptability and assess sensory differences of the
fortified breads.
White wheat flour will be fortified with either lysine, phosphorus, or both lysine and
phosphorus. The acceptability of these fortified breads will be tested.
L- Lysine monohydrochloride will be used as the sources of lysine. Potassium phosphate
will be used as the source of phosphorus. From previous experience, the addition of
potassium phosphate to glucose solution was found to minimally affect the organoleptic
properties. Unlike that of sodium phosphate that was not well tolerated by subjects due
to development of unfavorable flavor (fishy flavor).
Locally produced white wheat flour (80% extraction) will be purchased and stored at the
department. White flour samples will be analyzed for their content of phosphorus
according to standard procedures.
Fortification:
Fortification with lysine: 625mg of L-lysine monohydrochloride will be added to 100g of
wheat flour, giving a fortification rate of 500mg of lysine (0.5%) in 100g of wheat
flour.
Fortification with phosphorus: Phosphorus will be added to white wheat flour in the
proportion of 500mg of phosphorus in 100g of white wheat flour, and this will add up to a
total of 608mg of phosphorus in 100g of fortified white wheat flour (with 108mg of
phosphorus initially present in 100g of unfortified white wheat flour).
Making of breads:
Four different types of bread will be made:
White bread unfortified (WB) White bread fortified with lysine (WB-L) White bread
fortified with phosphorus (WB-P) White bread fortified with lysine and phosphorus (WB-LP)
Acceptability of the four different breads:
Bread samples will be tested for acceptability. Panelists (n= 60) will be recruited based
on their willingness to participate in the study and their consumption of Arabic bread.
Panelists will be asked to fill a questionnaire and to rate the served samples on a
9-point hedonic scale with 1 representing dislike extremely and 9 representing like
extremely for overall acceptability, acceptability of appearance, texture and taste. The
order of presentation of the samples will be counterbalanced.
Sensory evaluation of the four different breads:
Panelists (n=24) who are regular consumers of white bread will be recruited to assess any
sensory differences between experimental samples of the white bread control and the three
white breads supplemented with lysine and/or phosphorus. The triangle test will be used
in the difference tests.
All subjects will be asked to sign human subjects consent forms and answer demographic
information. Demographic information that will be requested will be: 1) age, 2) gender,
3) frequency of bread consumption, 4) type of bread typically consumed, and 5) what
factors influence the panelists' bread purchase.
Twenty four panelists will participate in three triangle test, comparing the white bread
control vs. each of the three experimental samples in each test. In the session, subjects
will be debriefed about a) the products they will consume, b) the procedures for the
testing, c) instructions on how to sample the beverages, and d) how to use the score
card. All samples will be presented in a random, balanced order.
Mineral and carbohydrate content of bread:
Phosphorus content of the breads will be determined.
Specific Aim 2: Determine the glycemic response following the consumption of the
different fortified breads.
In this experiment, healthy subjects (n=12) will be recruited and asked to maintain their
regular dietary and physical activity habits during the entire study course, avoid
alcohol consumption as well as any unusual strenuous exercise 24 hours prior to the
study.
Exclusion criteria: any significant medical diseases; pregnancy or lactation; regular use
of medication that affects body weight; a weight loss of 3% or more in the preceding 3
months.
Following a 12 hour (overnight) fast, subjects will be taken to the testing facility
[Faculty of Agriculture and Food Sciences/Department of Nutrition or the Central research
unit (CRU)/ American University Hospital] where anthropometric measurements (height,
weight) will be taken. A catheter will be inserted for blood withdrawal.
Postprandial glycemic response after consumption of the four fortified breads will be
determined.
A crossover design will be used in which each subject will undertake 4 visits in a random
order over 4 different days, the difference between the visits being the type of bread to
be consumed.
In brief, overnight fasted subjects will be given the bread (50 g of carbohydrate) to
ingest within 10-15 min and drink 250 ml of water. Blood samples will be taken
immediately before the meal and at 15, 30, 45, 60, 90 and 120 minutes after meal
ingestion. Blood will be withdrawn by a trained practitioner and will be used for the
determination of glucose.
Glucose area under the curve (AUC) will be calculated. In addition, mineral and several
metabolites content of the blood will be measured (glucose, total phosphorus,
triglycerides, insulin and GLP-1).
Specific Aim 3: Evaluate the variation in Energy Expenditure after the consumption of the
fortified breads.
Subject recruitment: 16 healthy subjects in total will be recruited. 14 subjects will be
required in order to be able to detect significance at the level of 0.05, using a 25%
difference between treatments and 90% power. But, a total number of 16 subjects will be
recruited in order to allow for the loss which might take place due to the dropping out.
Inclusion criteria: 16 subjects (BMI between 20 and 25) will be recruited. Efforts will
be made to age and gender match subjects (balanced number of males and females in each
group). Subjects are appropriate if they are in the age range between 18 and 60. Women
who are in the reproductive age will be studied at the first half of their menstrual
cycle, because estrogen is known to affect the energy expenditure. Postmenopausal women
taking hormonal replacement therapy will be excluded. Subjects should have: Cr <1mg/dl
for women and <1.2mg/dl for men and GFR >60 ml/min/1.73m2.
