By Products Technology
Compiled By: - Mr. Girish Rajpurohit
Q. What do you mean
by dairy by-product?
A. A dairy by-product may be
defined as a product of commercial value produced during the manufacture of a
main product. Skim milk, buttermilk, ghee residue and whey are the main dairy
by-products.
Q. Explain
disposable problems of whey?
A. The presence of significant
amount of organic matter (6-7% total solids) in the form of protein, lactose,
fat, minerals and water-soluble vitamins, its disposal causes environmental
pollution also the biological oxygen demand of whey is very high (40,000 mg/kg
or more), constituting a major economical burden to be disposed of as a waste
material.
Q. What is Skim
milk?
A. As per FSSAI (2011) skimmed milk
means the product prepared from milk from which almost all the milk fat has
been removed mechanically and it should have not more than 0.5% fat and minimum
8.7% milk SNF.
Q. Compare between
spray dried buttermilk powder and skim milk powder?
A. Spray dried buttermilk powder is
less free flowing and dusty.
Q. Why sweet whey
is preferred over acid whey for lactose manufacture?
A. Because sweet whey has high
lactose content and low ash content.
Q. Specific gravity
of skim milk at 15.50C is approx?
A. 1.036 kg/m3
Q. Factors
affecting specific gravity of skim milk?
A. Ratio of solid to liquid fat and
in the degree of hydration of the proteins.
Q. Viscosity of
skim milk at 20oC is approx.?
A. 1.5cp
Q. Important
contributor to viscosity is?
A. Casein micelles. There is
decline of viscosity from 5 to 30oC, reflecting a decrease in voluminosity of
the caseinate micelles. Above 30oC, the decrease is less marked until about
65oC, where the whey proteins begin to be denatured.
Q. Surface tension
of skim milk at 20oC is approx.?
A. 51 dynes/ cm
Q. Which component
mainly contributes to the conductivity of the milk?
A. Chloride
Q. Refractive index
of skim milk is approx.?
A. 1.34
Q. Factors having
role in determining the heat stability of milk?
A. Heat induced
interaction between β-Lg and k-casein plays a major role in determining
the heat stability and rennet clotting behavior of milk.
Q. What is edible casein?
A. Edible casein products mean the
products obtained by separating, washing and drying the coagulum of skimmed
milk.
Q. What is the milk fat standard of edible
casein?
A. Not more than 2%m/m.
Q. What is the milk
protein standard for rennet casein?
A. Not less than 84% on dry matter
basis.
Q. What is the
standard of lactose in edible casein?
A. Not more than 1%m/m.
Q. What is the
standard for ash including P2O5 in acid casein?
A. Not more than 2.5%m/m.
Q. What is the iso
electric point of casein?
A. It is pH 4.6.
Q. Which acid is
preferred, to adjust pH of wash water during manufacture of acid casein?
A. Sulphuric acid.
Q. Temperature of
precipitation during manufacture of hydrochloric acid casein should be
approximately?
A. 370C.
Q. Why we prefer
low amount of calcium after washing?
A. It is important to keep the
mineral content, particularly that of calcium, as low as possible in acid
casein to maintain high solubility and low viscosity of the casein
Q. What pH of initial water required to be same
as that of the casein curd?
A. The pH of wash water should be
about 4.6 for first two washings to avoid the formation of a gelatinous layer
over the curd particles in excessively acid water and softening and
redispersion of the curd in alkaline waters.
Q. What is the
yield of edible acid casein?
A. The yield of edible acid casein
is about 3 kg/100 kg skim milk.
Q. The short
residence time of casein in the pneumatic ring drier avoids?
A. Heat damage.
Q. The holding time
of each washing during continuous manufacture of hydrochloric acid casein is
approx.?
A. 20-30minutes.
Q. Cooking
temperature of curd during manufacture of lactic casein is approx.?
A. 50-55°C
Q. During
manufacture of rennet casein, setting time given to skim milk curd is approx.?
A. 20-30minutes.
Q. Compare rennet
casein and acid casein based on the total protein content?
A. Acid casein will have more
protein content than rennet casein because due to rennet action GMP (glycol
macro peptide) which is a protein gets drained off in whey.
Q. Microbial origin
rennet is obtained from?
A. Mucor miehei and Mucor
pulsillus
Q. What is the secondary stage of rennet action?
A. In
the second stage of the reaction, the remaining para k-casein forms
a three dimensional clot in the presence of calcium ions.
Q. The cooking
temperature employed in making rennet casein usually is approx.?
A. 50-60°C.
Q. During
manufacture of rennet casein, increase in washing temperature promotes?
A. Expulsion of whey constituent
from within the particles.
Q. Which property
of casein is used in finishing coating?
A. Film forming properties.
Q. Polyol
plasticised casein is used in finishing operations in?
A. Leather industry.
Q. Why oil and
glycerol are added to the casein?
A. To increase plasticity.
Q. Which filler can
be used to produce a white or opaque plastic/
A. Zinc or titanium oxide.
Q. The caseinate
content in paint is approx.?
A. 1-2%
Q. pH and
temperature of casein suspension and solubilization are controlled mainly
because of their influence on?
A. Viscosity of sodium caseinate
solution.
Q. Before spray
drying, viscosity of sodium caseinate solution is minimized by preheating to a
temperature of?
A. 90-95°C.
Q. Citrate
caseinate is prepared by addition of/
A. Trisodium citrate.
Q. Calcium caseinate
solution may be destabilized on heating at pH?
A. pH<6.
Q. During
manufacture of calcium caseinate, the heating of dispersion is done at approx.?
A. 700C.
Q. In single
stage process of hydrolysis, the common enzyme used is?
A. Trypsin.
Q. Pepsin type of
protease is characterized by preference for amino acids with?
A. Free carboxyl group.
Q. Trypsin types
are characterized by a preference for amino acids with?
A. Basic group.
Q. Enlist important
techniques of debittering of the protein hydrolysates?
A.
Selective separation of bitter components, masking, enzymatic treatment
and palstein reaction.
Q. In bitter casein
hydrolysates, activated carbon functions as a?
A. Hydrophobic adsorbent.
Q. Azeotropic
mixture is very effective in reducing bitterness?
A. Secondary butanol & water.
Q. Masking of
bitterness in casein hydrolysates is done by using?
A. Amino acids (
aspartic acid, glutamic, taurine in acid solution and glycine),
Fatty
substances, cyclodextrin, gelatin, Polyphosphates and starch.
Q. What kind of compound platein
is in respect to bitterness?
A. Bitterless
compound.
Q. What is plastein reaction?
A. The plastein
reaction is a process in which proteins are broken down by proteolytic enzymes
into a mixture of peptides and amino acids.
Q. Explain the synthesis of
plastein?
A.
·
The protein is enzymatically hydrolysed to a
low molecular weight mixture of peptides.
·
After hydrolysis, the impurities which cause
undesirable odours, colours and flavours are removed. Hydrolysis, however,
results in a characteristic bitterness which has been attributed to peptides
with more than three amino-acids. This material serves as substrate for the
third step of plastein synthesis.
·
During plastein synthesis, a high
concentration of hydrolysate (30-50%) is incubated with an enzyme or heated to
form viscous gel like material.
Q. Process of formation of
co-precipitate?
A.
·
Heat
treatment of milk or a mixture of products which provide casein and whey
protein, and
·
Precipitation of the proteins from the heated
milk.
Q. According to
Muller et al., (1967) classification, calcium content in medium calcium
coprecipitates is approx.?
A. 1.5%.
Q. According to
Muller et al., (1967) classification, calcium content in high calcium
coprecipitates is approx.?
A. 2.5-3.0%.
Q. Functional properties of
co-precipitates are mainly affected by?
A. Calcium
chloride quantity.
Q. Compared to caseins,
Co-precipitates contain?
A. High protein
& low lactose.
Q. How much amount of protein can
be recovered by the process of manufacture of coprecipitates?
A. 97%.
Q. How calcium concentration in co-precipitates can
be maintained?
A. It can be maintained by adjusting pH and
Temperature of heating of skim milk as follows: a higher pH value at
precipitation results in a higher calcium concentration in the product, while
the longer retention time at high temperature decreases calcium concentration.
Q. High calcium co-precipitates
are manufactured by heating of milk at?
A. 90°C/1-2 min.
Q. Compare addition of CaCl2
in making low, medium and high
calcium co-precipitates?
A. In low Ca
co-ppt : 0.03% CaCl2
In medium Ca co-ppt : 0.06% CaCl2
In high Ca co-ppt : 0.2% CaCl2
Q. Compare heating time of milk
in making low, medium and high calcium co-precipitates?
A. In low Ca co-ppt : 90°C/15-20 min.
In medium Ca co-ppt : 90°C/10-12
min.
In high Ca co-ppt : 90°C/1-2 min.
Q. Compare precipitation pH in
making low, medium and high calcium co-precipitates?
A. In low Ca
co-ppt : 4.6
In medium Ca co-ppt : 5.4
In high Ca co-ppt : around 6
Q. What should be the moisture
content after pressing stage in making of co-ppt?
A. 55-60%
Q. Amount of sodium
tripolyphosphate in the making of dewatered low, medium and high CO-PPT?
A. For spray
drying, the wet curd of low, medium and high calcium co-precipitates are
dispersed in water containing 2, 4 and 6 percent sodium tripolyphosphate (STPP)
respectively, calculated on the dry weight basis of the curd.
Q. Density of soluble high
calcium co-precipitates is approx.?
A. 0.3 g/ml.
Q. The development
of “gluey” off-flavours in low calcium co-precipitates can be inhibited by the
addition of approx.?
A. 0.03 % sodium metabisulphite.
Q. Lactose content
in granular medium calcium co-precipitates is approx.?
A. 0.5 %.
Q. Protein content
of whey obtained from co-precipitates is approx.?
A. 0.3%.
Q. Viscosity of whey
at 20oC is approx.?
A. 1.26 cP.
Q. Surface tension
of cheese whey is approx.?
A. 42 dyne/cm.
Q. During whey
concentration, the purpose of fat separation is to?
A. Improve flavour stability.
Q. Comment of
solubility of lactose?
A. The solubility of lactose is
only about 20 g/100 g water at room temperature and 60 g/100 g water at 60°C.
Q. Which of the
followings (acid whey, paneer whey and cheese whey) is preferred for
manufacture of whey based vegetable soups?
A. Cheese whey.
Q. What is
acidowhey?
A. “Acidowhey” is a non-carbonated
drink, fermented with selected strain of lactic acid bacteria and retaining all
the nutrients of whey intact. It was developed in Ndri.
Q. Whey champagne
is?
A. Alcoholic wine like drink.
Q. ‘BEL’ process is
used for production of?
A. Single cell protein.
Q. Galactose can be
produced from whey by using?
A. Kluyveromyces fragilis.
Q. Dextrans can be
produced from whey by using?
A. Leuconostoc mesenteroides.
Q. Inorganic
fouling of electrodialysis membrane is caused by?
A. Silicates.
Q. Organic fouling
of electrodialysis membrane is caused by?
A. Proteins.
Q. Explain feed and bleed module in
electrodialysis?
A. This is a combination of batch
and continuous modes and involves recycling of feed stock with continuous small
removal of product, compensated by equivalent feed rate.
Q. What is the level of demineralisation of
whey-based fluids can be achieved by ion exchange?
A. 95% demineralisation .
Q. The use of lower
temperature of 10oC during ion exchange will?
A. Reduce the extent of losses of
protein & lactose.
Q. In ion exchange
process using strong base resin, the Demineralisation is carried out at
temperature?
A. 35-50°C.
Q. Functional group
of cation resin in SMR process is?
A. Ammonium ion.
Q. Functional group
of anion resin in SMR process is?
A. Bicarbonate ion.
Q. Cold
precipitation process involves recovery of whey proteins by?
A. Complexing agent.
Q. Adsorption
method used for whey protein recovery is based on?
A. Ion Exchange.
Q. What % protein
can be recovered from whey by ultrafilteration process?
A. 80%.
Q. Lactose content
in WPC 80% is approx./
A. 5%.
Q. In whey protein
concentrates, high ash content may inhibit their?
A. Emulsion and foaming capacity.
Q. What is the use
of UF permeate as starting material for lactose manufacture?
A. Reduces crystalline time,
Increases lactose yield and Increases purity of lactose.
Q. In lactose
crystallization, lactose seed must be added in the form of?
A. α-lactose monohydrate.
Q. α- form of
lactose crystallises at?
A. < 93.5°C.
Q. Lactose content
of crude lactose is approx.?
A. 95-99%.
Q. Lactose content in food grade lactose is/
A. 98-99%.
Q. Moisture content
in pharmaceutical lactose is/
A. 0.1%.
Q. Drying process
preferred for lactose is?
A. Fluidized bed drying.
Q. Lactose grade
having highest purity of lactose is?
A. Pharmaceutical grade lactose.
Q. Lactose form
brown pigment by reacting with?
A. Peptides and amino acid.
Q. Based on which
property μ-Lactose is used as a dispersing agent in food and pharmaceutical
industry?
A. Non- hygroscopic and free flowing
property.
Q. Solubility of
lactose is approx.?
A. 18%.
Q. Lactose is
hydrolysed to yield?
A. Glucose and galactose.
Q. Acid hydrolysis
of lactose is done by?
A. Cation exchange resin.
Q. Why hydrolysed
lactose is used in caramels?
A. To reduce lactose
crystallization.
Q. Above 650C,
relative viscosity of whey increases as a result of?
A. Protein denaturation.
Q. Calcium
caseinate is used when following property of solution is desired?
A. Low viscosity & high
turbidity.
Q. Which functional
properties of casein increases by dephosphorylation?
A. Surface activity.
Q. In khoa, greater
amount of WPC produces?
A. Bigger grains.
Q. In beer &
wine industries, casein products are mainly used to?
A. Reduce colour and astringency
and as Fining & clarifying agent.
Q. Spray dried
buttermilk is less free flowing and dusty than skim milk powder because of?
A. High fat content.
Q. Titrable acidity
of sweet cream buttermilk is approx.?
A. 0.12%.
Q. Which is
principal fatty acid in phospholipids of buttermilk?
A. Palmitic acid.
Q. Toning of buffalo milk with
sweet cream buttermilk improves its?
A. Heat stability.
Q. Addition of
sweet cream buttermilk to cheese results into softer body due to presence of higher
amount of?
A. FGM materials
(fat globular membrane).
Q. Butter milk improves the
textural properties of rasogolla due to their?
A. High lecithin
content.
Q. Curd prepared by
incorporating sweet cream buttermilk into whole milk has soft-body, due to?
A. Change in the
electric charge on casein during churning, Presence of phospholipids &
other MFGM materials and Presence of free fat in the buttermilk.
Q. Oxidative stability of ghee
can be increased by increasing?
A. Phospholipid
content.
Q. Efficiency of pressure
technique for recovery of ghee from ghee-residue is about?
A. 67%.
Q. Efficiency of
centrifugation process for recovery of ghee from ghee-residue is about?
A. 46%.
Q. In the preparation of burfi, ghee-residue
is mixed with khoa in the ratio of?
A. 1:1.
Q. PER value of casein is
approx.?
A. 2.50.
Q. PER value of co-precipitates
is approx.?
A. 3.30.
Q. Dominant factor in depressing
PER of ghee-residue?
A. Lower lysine
content.
Q. PER of ghee-residue is
approx./
A. 0.66.
Q. PER value of whey proteins is
approx.?
A. 3.6
Q. Lactulose is hydrolyzed by?
A. Lactobacillus
acidophilus and Bifidobacterium bifidus.
Reference:
·
ICAR E-
course
·
NDRI
class notes.
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