This presentation discusses hydroxyapatite, a type of calcium phosphate mineral. Hydroxyapatite can be synthesized through several chemical methods and is used to fortify milk and dairy products with calcium. When soluble calcium salts are used to fortify milk, they can cause protein aggregation and instability during ultra-high-temperature processing. Insoluble calcium salts like hydroxyapatite are generally used for fortification instead, but can cause shelf life issues like separation over time. The document explores how milk proteins interact with and adsorb onto hydroxyapatite particles, which could impact the colloidal stability of fortified milk products.

1. welcome

2. Presentation on:
Hydroxyappatite
Presented by:
M. Archana
1st Yr Mtech
Dairy Chemistry

3. Hydroxyappatite:
Hydroxy appatite is a insoluble crystalline mineral of calcium
phosphate known as hydroxy appatite with chemical formula
Ca10 (PO4)6 (OH)2
Chemical synthesis of hydroxyapatite:
Hydroxyapatite can be synthesized via several methods such as wet
chemical deposition, biomimetic deposition, sol-gel route (wet-
chemical precipitation) or electrodeposition.

4. Interaction of hydroxyappatite with milk proteins and
minerals:
 Bone health is an issue of growing importance with osteoporosis
on the increase largely due to and ageing global population(Gurr,
etal., 1999).
 Dietary calcium is a crucial factor in maintaining the bone health
and combating osteoporosis(Heney etal., 2000).
 Therefore calcium fortification is a growing trend in food
industries this is especially true for milk and dairy products as
they all naturally rich in calcium and already wellknown for their
benefits for bone, health.(Augustin and williams, 2002)

5.  Milk in its natural state contains approximately 120mg of
Calcium per 100g (Lucey and Horne, 2009) to fortify milk and
dairy products further with calcium, calcium salts such as calcium
chloride, calcium phosphate, calcium citrate need to be added to
milk.(Grandison and Lewis, 2010; Singh etal., 2007).
 Selecting a good source of calcium for fortification requires a
good understanding of its physical and chemical properties and
how it interacts with milk components(Philippe, Gucheron,
20003).
 UHT treatment increases the shelf life of liquid milk by rendering
them sterile and bacteriologically stable for several months at
ambient temperature (Datta and Deeth, 2001)

6.  UHT treatment of unfortified milk is rarely a problem as it can
withstand such heat treatment without any major issue, however
there are a number of practical issues related to the processing
and formulation of calcium fortified UHT milk, that makes it
challenging to maintain stability of product over its intended shelf
life .
 If soluble calcium salts such as calcium chloride, calcium lactate
are used to fortify milk with calcium their addition can lead to
protein aggregation and heat instability during the UHT
treatment.
 The mineral equilibrium is disrupted by the soluble salts there by
reducing the electrostatic repulsion between the micelles and
leading to their aggregation on heat treatment.

7.  In commercial UHT calcium fortified milk, insoluble calcium
salts such as Tricalcium phosphate, Hydroxyappatite and
calcium carbonate are usually used as calcium fortificants.
Since they are considered to be chemically unreactive in milk
therefore not causing heat instability.
 But the use of such calcium (insoluble) forms causes shelflife
instability, such as phase separation and sedimentation
occurs(Gucheron, 2003).
 It is well known that HA does interact with proteins, as proteins
adsorbed strongly onto HA in a wide range of biological
applications such as bioceramics material,
chromatography(Kawasaki, 1991 and Zhang, 2012).

8.  Milk protein adsorption on to HA particles may occur in
calcium fortified milks, and could potentially modify the
colloidal stability of the HA particles in the product or the
stability of milk protein fraction.
 The adsorption behavior of αs1-CN, β-CN, k-CN, α-La and β-
Lg on HA was characterized by determination of adsorbed
protein levels and surface charge of HA.

15. Thank you