Maillard reaction in milk powder
Faculty: Faculty of Applied Science
Program: Bachelor (Hons) Food Science and Technology
Program Code: AS246 5L
Course: Food Chemistry I
Course Code: FST603
Semester: 5
Group Members:
NAME MATRIC ID
SYAZA HUSNA BINTI ROSLI 2015117713
AISHA KHALEDA BINTI AZHAR 2015106339
NOOR AMIZA NADZLIN BINTI MOHD NAZARI 2015149631
NOR FATIN ARISYA AFIQAH BINTI ISMAIL 2015102417
Submitted to:
Dr. Anida binti Yusoff
On 11th June 2018

TABLE OF CONTENTS:
INTRODUCTION ………………………………………………………….. 3-4
REACTION OF MAILLARD ……………………………………………… 5-7
ADVANTAGE OF MAILLARD REACTION ……………………………… 8
DISADVANTAGE OF MAILLARD REACTION …………………………. 8-9
PREVENTION TO MAILLARD REACTION ………………………………10-11
CONCLUSION ……………………………………………………………….11
REFERENCES ………………………………………………………………..12-13
INTRODUCTION
Maillard reaction is named after the first person who described the reaction that occurs between an amino group and a carbonyl group, Louis Camille Maillard in 1912. Maillard reaction is also commonly known as Non-enzymatic glycosylation and a thermally induced reaction. To be precise, it is the main reaction which usually occurs between proteins and reducing sugars in thermally-processed food. In most dairy products, the carbonyl compound is the reducing sugar lactose or it others hydrolysis products (glucose and galactose), and the amino groups could be derived from either casein or whey proteins which contain amino acid residues. Other sources of amine groups could include amino phospholipids or free amino acids, whilst milk fat provides another source of carbonyl compounds ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1039/c2fo30089c”, “ISBN” : “2042-6496”, “ISSN” : “2042-6496”, “PMID” : “22948260”, “abstract” : “Dairy products are heated both during processing and by consumers during food preparation; consumers place a high level of importance on flavour when assessing product acceptability. Of particular importance to the flavour of heated dairy products is the highly complex network of Maillard reactions. Much focus has been placed on the undesirable flavours generated through the Maillard reaction and how to minimise the formation of these flavours. However, beneficial flavours can also be formed by the Maillard reaction; dairy products, such as ghee, are formed by heating and are characterised by the unique flavour generated by this chemistry. This review looks at the Maillard reaction as a source of beneficial flavours for cooked dairy products and the application of models to the study of flavour formation in food systems. Models are typically used to study complex reactions in a simplified way; however, they are not always applicable to food systems. u00a9 2012 The Royal Society of Chemistry.”, “author” : { “dropping-particle” : “”, “family” : “Newton”, “given” : “Angela E.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Fairbanks”, “given” : “Antony J.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Golding”, “given” : “Matt”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Andrewes”, “given” : “Paul”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Gerrard”, “given” : “Juliet A.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Food & Function”, “id” : “ITEM-1”, “issue” : “12”, “issued” : { “date-parts” : “2012” }, “page” : “1231”, “title” : “The role of the Maillard reaction in the formation of flavour compounds in dairy products u2013 not only a deleterious reaction but also a rich source of flavour compounds”, “type” : “article-journal”, “volume” : “3” }, “uris” : “http://www.mendeley.com/documents/?uuid=38f8bee0-fe22-4940-8df4-7024c4d2046c” } , “mendeley” : { “formattedCitation” : “(Newton, Fairbanks, Golding, Andrewes, & Gerrard, 2012)”, “plainTextFormattedCitation” : “(Newton, Fairbanks, Golding, Andrewes, & Gerrard, 2012)”, “previouslyFormattedCitation” : “(Newton, Fairbanks, Golding, Andrewes, & Gerrard, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Newton, Fairbanks, Golding, Andrewes, & Gerrard, 2012). This reaction happens in vary types of foods during heat processing treatment and storage in adverse conditions which then leads to generates different products depending on the stage of the reaction (Diego & Maite, 2017). The application of heat that applied to food products in manufacturing aims to assure microbiological safety and to promised lengthen the shelf-life of food products (Marilyn & Aalaei, 2018). The method of choice for heat treatment can be classify such pasteurization, sterilization, roasting, evaporation and drying. Maillard reaction in milk powder can create both desirable and undesirable change in milk in term of their flavor, color, aroma, texture and nutrition.
Production of milk powder involve a simple process with gentle removal of water under stringent hygiene conditions while retaining all the desirable natural properties of milk such as color, flavor, solubility and nutritional value. Initially, whole (full cream) milk contains about 87% water and skim milk contains about 91% water. These water is removed by boiling the milk under reduced pressure at low temperature know as evaporation. The result of concentrated milk is then sprayed in a fine mist with hot air (up to 200oC) to further remove the moisture and form milk powder. The fine milk powder contains around 2-4 % moisture content with mean of particle size of <0.1 mm diameter. Before inserting the milk into spray dryer, it undergo standardization (separate skim and cream from whole milk), preheating such as pasteurization at 72oC for 15s (to destroy the bacteria, inactivates enzymes, generates natural antioxidants and impart heat stability) as well as evaporation to concentrate the milk which achieve by boiling the milk under a vacuum temperatures below 72oC ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “author” : { “dropping-particle” : “”, “family” : “Pearce”, “given” : “K. N”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “id” : “ITEM-1”, “issued” : { “date-parts” : “0” }, “title” : “Dairy Milk Powder”, “type” : “article-journal” }, “uris” : “http://www.mendeley.com/documents/?uuid=aa166d74-1312-3d23-861b-1d8cfe131c18” } , “mendeley” : { “formattedCitation” : “(Pearce, n.d.)”, “plainTextFormattedCitation” : “(Pearce, n.d.)”, “previouslyFormattedCitation” : “(Pearce, n.d.)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Pearce, n.d.). All of these heat treatments during production of milk powder may contribute to Maillard reaction.

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The main purpose production of milk powder is to stabilize milk constituents for their storage and later use. Despite of wide range of target group for the consumers, milk powder main target group belong to the infants. Milk powder also widely use in the formulations of chocolate, bakery products, dairy product, meat, dried, frozen and ready to eat meals ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1080/10408398.2018.1431202”, “ISSN” : “1040-8398”, “author” : { “dropping-particle” : “”, “family” : “Aalaei”, “given” : “Kataneh”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Rayner”, “given” : “Marilyn”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Sju00f6holm”, “given” : “Ingegerd”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Critical Reviews in Food Science and Nutrition”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2018” }, “page” : “1-11”, “title” : “Chemical methods and techniques to monitor early Maillard reaction in milk products; A review”, “type” : “article-journal”, “volume” : “8398” }, “uris” : “http://www.mendeley.com/documents/?uuid=20ffaac0-9016-4d31-a8ef-cbd0611f3916” } , “mendeley” : { “formattedCitation” : “(Aalaei, Rayner, & Sju00f6holm, 2018)”, “plainTextFormattedCitation” : “(Aalaei, Rayner, & Sju00f6holm, 2018)”, “previouslyFormattedCitation” : “(Aalaei, Rayner, & Sju00f6holm, 2018)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Aalaei, Rayner, & Sjöholm, 2018).
The nature of the Maillard reaction depend on many factors, including water activity (aw) where it should be at optimum condition between Aw: 0.6-0.7. Next, the pH in Maillard reaction should not be in acidic condition as it can cause much longer lag period. Other than that, temperature and the physiochemical state of the components also contributes to the factor of Maillard reaction. The temperature of milk powder storage can influence the Maillard reaction. For example, milk powder stored at high temperature (50oC) and increase in storage humidity accelerate Maillard reaction ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1039/c2fo30089c”, “ISBN” : “2042-6496”, “ISSN” : “2042-6496”, “PMID” : “22948260”, “abstract” : “Dairy products are heated both during processing and by consumers during food preparation; consumers place a high level of importance on flavour when assessing product acceptability. Of particular importance to the flavour of heated dairy products is the highly complex network of Maillard reactions. Much focus has been placed on the undesirable flavours generated through the Maillard reaction and how to minimise the formation of these flavours. However, beneficial flavours can also be formed by the Maillard reaction; dairy products, such as ghee, are formed by heating and are characterised by the unique flavour generated by this chemistry. This review looks at the Maillard reaction as a source of beneficial flavours for cooked dairy products and the application of models to the study of flavour formation in food systems. Models are typically used to study complex reactions in a simplified way; however, they are not always applicable to food systems. u00a9 2012 The Royal Society of Chemistry.”, “author” : { “dropping-particle” : “”, “family” : “Newton”, “given” : “Angela E.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Fairbanks”, “given” : “Antony J.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Golding”, “given” : “Matt”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Andrewes”, “given” : “Paul”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Gerrard”, “given” : “Juliet A.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Food & Function”, “id” : “ITEM-1”, “issue” : “12”, “issued” : { “date-parts” : “2012” }, “page” : “1231”, “title” : “The role of the Maillard reaction in the formation of flavour compounds in dairy products u2013 not only a deleterious reaction but also a rich source of flavour compounds”, “type” : “article-journal”, “volume” : “3” }, “uris” : “http://www.mendeley.com/documents/?uuid=38f8bee0-fe22-4940-8df4-7024c4d2046c” } , “mendeley” : { “formattedCitation” : “(Newton et al., 2012)”, “plainTextFormattedCitation” : “(Newton et al., 2012)”, “previouslyFormattedCitation” : “(Newton et al., 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Newton et al., 2012).

REACTION OF BROWNING IN MILK POWDER
Milk undergo various heat treatment such as low temperature long time (LTLT) pasteurization, high temperature short time (HTST) pasteurization and ultra-high temperature (UHT) treatment which cause Maillard reaction to occur in milk. Maillard reaction is a non-enzymatic browning reaction which involves complex chemical reaction between carbonyl group and amino group present in milk. Maillard reaction in milk powder usually take place during processing or storage. Maillard reaction occurs in three stages which are early, intermediate and advanced stages which then formed various kind of Mallard reaction products ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.5772/50079”, “author” : { “dropping-particle” : “”, “family” : “Shimamura”, “given” : “Tomoko”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Uke”, “given” : “Hiroyuki”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Milk Protein”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2012”, “9”, “12” }, “publisher” : “InTech”, “title” : “Maillard Reaction in Milk – Effect of Heat Treatment”, “type” : “chapter” }, “uris” : “http://www.mendeley.com/documents/?uuid=1329d356-806a-356c-b645-af8924d5ad4e” } , “mendeley” : { “formattedCitation” : “(Shimamura & Uke, 2012)”, “plainTextFormattedCitation” : “(Shimamura & Uke, 2012)”, “previouslyFormattedCitation” : “(Shimamura & Uke, 2012)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Shimamura & Uke, 2012). Rate of Maillard reaction is influenced by many factors, such as temperature, water activity, pH, reactant source as well as concentration, type and ratio of reducing sugar to lysine ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/j.idairyj.2009.07.007”, “ISSN” : “09586946”, “abstract” : “The kinetics of the Maillard reaction in skim milk powder was studied at a wide range of water activities (0.31-0.98) under storage at mildly elevated temperature conditions (37, 50 and 60u00a0u00b0C). The reaction rate was determined by the loss of available lysine content using the o-phthaldialdehyde method. Water activity affected the rate of loss of lysine above the glass transition temperature only at high water activity values. However, the mobility of the reactants seemed to play a role in damage to lysine, as the rate constant decreased considerably at temperatures close to the glass transition. Crystallization of lactose did not affect the rate constant values. Water activity did not influence the temperature-dependence of the reaction rate, although a significant increase in activation energy was observed in the vicinity of the glass transition temperature. u00a9 2009 Elsevier Ltd. All rights reserved.”, “author” : { “dropping-particle” : “”, “family” : “Pereyra Gonzales”, “given” : “A. S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Naranjo”, “given” : “G. B.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Leiva”, “given” : “G. E.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Malec”, “given” : “L. S.”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “International Dairy Journal”, “id” : “ITEM-1”, “issue” : “1”, “issued” : { “date-parts” : “2010” }, “page” : “40-45”, “publisher” : “Elsevier Ltd”, “title” : “Maillard reaction kinetics in milk powder: Effect of water activity at mild temperatures”, “type” : “article-journal”, “volume” : “20” }, “uris” : “http://www.mendeley.com/documents/?uuid=068a316f-eb32-4f05-a953-dd24ecd6f7f0” } , “mendeley” : { “formattedCitation” : “(Pereyra Gonzales, Naranjo, Leiva, & Malec, 2010)”, “plainTextFormattedCitation” : “(Pereyra Gonzales, Naranjo, Leiva, & Malec, 2010)”, “previouslyFormattedCitation” : “(Pereyra Gonzales, Naranjo, Leiva, & Malec, 2010)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Pereyra Gonzales, Naranjo, Leiva, & Malec, 2010).

Early stage of Maillard reaction involve the condensation between lactose and free amino acid side chain of milk protein (mainly ?-amino group of lysine residue) in both caseins and whey proteins and eliminates one molecule of water. Schiff’s base is then produced as the reaction continues which is then undergoes cyclization to produce N-substituted glcosylamine which is unstable. Unstable N-substituted glycosylamine undergoes transition, Amadori rearrangement to yield protein-bound Amadori compound (lactulosyllysine) ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/S0308-8146(98)00075-2”, “ISSN” : “03088146”, “author” : { “dropping-particle” : “”, “family” : “Boekel”, “given” : “M.A.J.S.”, “non-dropping-particle” : “Van”, “parse-names” : false, “suffix” : “” } , “container-title” : “Food Chemistry”, “id” : “ITEM-1”, “issue” : “4”, “issued” : { “date-parts” : “1998”, “8” }, “page” : “403-414”, “title” : “Effect of heating on Maillard reactions in milk”, “type” : “article-journal”, “volume” : “62” }, “uris” : “http://www.mendeley.com/documents/?uuid=042b38bc-d6c6-3e7e-9466-7d6dddeff2f8” } , “mendeley” : { “formattedCitation” : “(Van Boekel, 1998)”, “plainTextFormattedCitation” : “(Van Boekel, 1998)”, “previouslyFormattedCitation” : “(Van Boekel, 1998)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Van Boekel, 1998). Aldose sugar is converted to ketose sugar during Amadori rearrangement. Early stage of Maillard reaction reduces the amount of lysine which is one of essential amino acid present in milk. There is no or little change in color or flavor formation at this stage. According to Mauron (1981), the Amadori product in milk is stable as long as the heating condition is not too drastic or reaction time not too long.

Figure 1.1: Early stage of Maillard reaction in milk leading to formation of Amadori product (lactulosyllysine-R)
Advanced Maillard reaction involves further breakdown of Amadori compound via enol form of Amadori compound. It consist of the breakdown of Amadori product (or other products related to the Schiff’s base) into numerous fission products of sugar-amino compound ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/S0308-8146(98)00075-2”, “ISSN” : “03088146”, “author” : { “dropping-particle” : “”, “family” : “Boekel”, “given” : “M.A.J.S.”, “non-dropping-particle” : “Van”, “parse-names” : false, “suffix” : “” } , “container-title” : “Food Chemistry”, “id” : “ITEM-1”, “issue” : “4”, “issued” : { “date-parts” : “1998”, “8” }, “page” : “403-414”, “title” : “Effect of heating on Maillard reactions in milk”, “type” : “article-journal”, “volume” : “62” }, “uris” : “http://www.mendeley.com/documents/?uuid=042b38bc-d6c6-3e7e-9466-7d6dddeff2f8” } , “mendeley” : { “formattedCitation” : “(Van Boekel, 1998)”, “plainTextFormattedCitation” : “(Van Boekel, 1998)”, “previouslyFormattedCitation” : “(Van Boekel, 1998)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Van Boekel, 1998). There are two general breakdown routes at different pH. First route is 3-deoxyosone pathway via the 1,2 enolization route at pH<7 and the second route is 1-deoxyosone pathway via the 2,3-enolization route at neutral and alkaline pH. However, there are the third route which only significant for disaccharides at slightly alkaline conditions which is 4-deoxyosone pathway. Each routes lead to the formation of deoxyosone which are very reactive intermediates, therefore their formation is difficult to determine. The first route stated, 3-deoxyosone pathway, occurs in heated milk at acidic condition and leads to the formation of very small amounts of products such as hydroxymethylfurfural (HMF), furfural, furufurylalcohol and pyralline (Mauron, 1981; Led1 and Schleicher, 1990; Nursten, 1990; O’Brien, 1995). However, the degradation of Amadori compound in milk mainly occurs via the 2,3 enolization route due to the pH of milk (pH 6.6) leads to the formation of ?-pyranone, 3-furanone, cyclopentenone, and galactosylisomaltol. The third route, 4-deoxyosone pathway only happen in milk at alkaline condition upon prolong heating and formed 4-deoxyaminoreductone and 5,6-dihydro-3-hydroxypyridone. Besides that, advance stage of Maillard reaction will lead to the formation of advance glycation end product (AGEs) which are suspected to involve in autoimmune disease in humans

Figure 1.2: Advance reaction of Maillard reaction consist breakdown of Amadori compound at different pH.

The final stage of Maillard reaction consist of formation of brown pigment called as Melanoidins as well as condensation of amino compounds and sugar fragments into polymerized protein which contribute to flavor and aroma of milk powder. Reduction of lysine residue during Maillard reaction responsible to the formation of Melanoidins ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1016/S0308-8146(98)00075-2”, “ISSN” : “03088146”, “author” : { “dropping-particle” : “”, “family” : “Boekel”, “given” : “M.A.J.S.”, “non-dropping-particle” : “Van”, “parse-names” : false, “suffix” : “” } , “container-title” : “Food Chemistry”, “id” : “ITEM-1”, “issue” : “4”, “issued” : { “date-parts” : “1998”, “8” }, “page” : “403-414”, “title” : “Effect of heating on Maillard reactions in milk”, “type” : “article-journal”, “volume” : “62” }, “uris” : “http://www.mendeley.com/documents/?uuid=042b38bc-d6c6-3e7e-9466-7d6dddeff2f8” } , “mendeley” : { “formattedCitation” : “(Van Boekel, 1998)”, “plainTextFormattedCitation” : “(Van Boekel, 1998)”, “previouslyFormattedCitation” : “(Van Boekel, 1998)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Van Boekel, 1998).
THE ADVANTAGES OF MAILLARD REACTION IN MILK POWDER
According to University of Sydney, Maillard reactions don’t really only take place in a hot oven, they can also occur slowly at ambient temperature resulting in gradual changes to aroma, flavor, color, appearance, texture, shelf-life and nutritional value of stored foods. In this way, Maillard reactions are responsible for deterioration during storage of dry goods powdered milk.
The development of the furan derivatives during Maillard reaction by sugar degradation and dehydration give flavor to milk powder but their levels were below the perception threshold. In addition, development of furan derivatives gives sweet, nutty and caramel color which is commonly more important for condensed milk (Newton, Fairbanks, Golding, Andrewes, & Gerrard, 2012).
Some of the complex product also known as Maillard reaction products(MRPs) resulting from Maillard reaction in dairy product including milk powder exhibits beneficial consequences on antioxidant properties as dairy foods do not contain any other substances with high antioxidant capacity(Yanez, Gagneten, Leiva & Malec, 2017).
THE DISADVANTAGES OF MAILLARD REACTION IN MILK POWDER
During the Maillard reaction in milk, lactose basically with react with ?-amino group of lysine residue of milk protein resulted in lysine loss (Rayner & Sjoholm,2018) with a severity of heat treatment at 37, 50 and 60°C as the modified lysine loss it nutrient as Amadori compound is produced (Shimura & Ukeda,2012). In addition, the influence of water activity on Maillard reaction kinetics in milk powder as a consequence of concentration and diffusion of reactants next affect the rate of loss of lysine (Gonzales, Naranjo, Leiva and Malec, 2010).
Moreover, the lysine residues in skim milk powder were more susceptible to heating than those in skim milk because Lysine residues in milk proteins become “blocked” when they react with reducing sugars, particularly lactose, in the Maillard reaction. The blocked or glycated lysine reduce the biological availability of the lysine to metabolic processes and also hinder hydrolysis of the parent protein by digestive enzymes (Mehta and Deeth, 2015). Besides lysine, sulphur-containing amino acids also got effected as high temperature lead to slight destruction.
According to U.S. Dairy Export Council with the collaboration of Dr. N. Farkye, slight browning may link with flavor changes which makes the milk powder less desirable in production of yogurt, ice cream and other dairy products. Next, milk powder develops stickiness, caking and lumpiness during storage process due to hygroscopic behavior as the lactose content is high. Once it has been exposed to the atmosphere, it can absorb sufficient moisture to induce caking or the development of lumps, resulting in poor flows of milk powder.
Other than that, Maillard reaction also as one of the mode of deterioration in milk powder which may limit shelf life. High concentration of lactose and protein in lysine content allow these components readily participate in Maillard reaction which changes the protein structures (primary, secondary and tertiary) that is followed by undesirable color changes and hence reduces the functionality such as solubility of the milk powder (Intipunya & Bhandari, 2010).
Loss of nutritional values by Maillard reaction also due to the formation of toxic and mutagenic compound (Martins, Jongen & Boekel, 2001). Maillard reaction induces crosslinking of amino acids to form inter- and intramolecular bonded species. Only a small amount of crosslinking of proteins at the interface of the powder particles during storage may be adequate to reduce the solubility of milk protein concentrate powder (Anema et al., 2006). 
Formation of AGEs compound during the advance stage of Maillard reaction create disadvantage in humans. ADDIN CSL_CITATION { “citationItems” : { “id” : “ITEM-1”, “itemData” : { “DOI” : “10.1080/10408398.2018.1431202”, “ISSN” : “1040-8398”, “author” : { “dropping-particle” : “”, “family” : “Aalaei”, “given” : “Kataneh”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Rayner”, “given” : “Marilyn”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” }, { “dropping-particle” : “”, “family” : “Sju00f6holm”, “given” : “Ingegerd”, “non-dropping-particle” : “”, “parse-names” : false, “suffix” : “” } , “container-title” : “Critical Reviews in Food Science and Nutrition”, “id” : “ITEM-1”, “issued” : { “date-parts” : “2018” }, “page” : “1-11”, “title” : “Chemical methods and techniques to monitor early Maillard reaction in milk products; A review”, “type” : “article-journal”, “volume” : “8398” }, “uris” : “http://www.mendeley.com/documents/?uuid=20ffaac0-9016-4d31-a8ef-cbd0611f3916” } , “mendeley” : { “formattedCitation” : “(Aalaei et al., 2018)”, “plainTextFormattedCitation” : “(Aalaei et al., 2018)”, “previouslyFormattedCitation” : “(Aalaei et al., 2018)” }, “properties” : { }, “schema” : “https://github.com/citation-style-language/schema/raw/master/csl-citation.json” }(Aalaei et al., 2018). As explained in the reaction above, Maillard reaction will form glycated proteins which in high amounts in the body lead to the activation of RAGE (a special receptor for AGEs) and induce a pro-inflammatory status in the body which lead to the chronic disease such as diabetes, renal disease, allergy and coronary heart disease.
Some aspects of Maillard reaction also have long term implication in human ageing and health conditions, for examples include loss of elasticity of the connective tissue, the appearance dark spots on skin due to effects on collagen and cataract formation due to reactions with the lens protein crystalline (Copeland, 2016).

PREVENTION/CONTROL TO MAILLARD REACTION
Undesirable Maillard reaction that occur on milk product can be controlled by several preventive actions. Once we know the factor that contributes to Maillard reaction, it is easy for us to inhibit the reaction to occur. For your information, there are several factors that are affecting Maillard reaction which is temperature, moisture content, metal ions, sugars and lastly pH. As we know, different factor can give different effect on the final product of Maillard reaction product (Diego A. et al., 2017).

The first factor is temperature. When the temperature used is increase this will resulting in rapid increase in rate of browning for 2-3 times for each 10?C rise in temperature. High temperature result in changes in color and flavor of product. The desirable Maillard reaction occur where there is changes in color and flavor usually applied on product such as bread, chocolate, coffee and beer however not in milk product. Maillard reaction that occurred in milk is called as undesirable Maillard reaction since it gives undesirable changes in milk powder. It can be controlled by lowering the temperature used in order to prevent the color of milk become brown and we also can add antioxidant as we know antioxidant can preserve the food product from oxidation reaction (Diego A. et al., 2017).

Secondly is moisture content. The highest rate of browning reaction is occurred at intermediate water activity where the aw range is between 0.6 to 0.7 (P. Intipunya and B.R. Bhandari, 2010). If the aw is exceeding 0.7 or below than 0.6, it will help to degrade and restrict mobility of the compound. In order to control the browning in product, it is important to control the moisture content as when the moisture content is less in milk product it will reduce the mobility of reactant in milk product.

Next factor is metal ions. We should ensure that there is no presence of Cu and Fe that enhance browning at later steps in Maillard reaction which involve oxidation-reduction reactions. An oxidation-reduction reaction can be a catalyst to Maillard reaction to occur. So that is important to make sure there is no metal ions present in milk product.
Furthermore, sugar that contain in milk which is lactose is a reducing sugar. All disaccharide except sucrose is a reducing sugar where it has an open chain structure. The greater the extent in an open chain, the greater the rate of Maillard reaction will occur. This factor can be controlled by using an enzyme or Sulphur dioxide. When an enzyme is used, it will remove the active compound in the sugar present and it will reduce the amount of reducing sugar present in solution and unable to combine with amino acid. Meanwhile, Sulphur dioxide will react with degradation product of amino sugar to convert the amino sugar where it can help to stop the pathway and preventing these compound from condensing into melanoidin.

Last but not least, the factor that affecting Maillard reaction is pH. In Maillard reaction condition, it prefer alkaline condition as the intensity of reaction is increases with increase in pH. The optimum pH is in range of 6-8 and it is the optimum condition where more hexoses in open chain in reducing sugar. However, in milk product in order to reduce undesirable changes towards the product, we need to reduce the pH to acidic condition.

CONCLUSION
According to P. Intipunya and B.R. Bhandari, (2010) Maillard reaction is a non-enzymatic chemical reaction between carbonyl (primarily carbohydrates) and amino compounds. Maillard reaction can be divided into two reaction which is desirable Maillard reaction and undesirable Maillard. The desirable Maillard reaction give advantages in food product usually occurred in baked product such as bread and cake where it gives desirable color to final product. Meanwhile undesirable Maillard reaction usually occurred in milk product where it can affect the color and flavor of milk where the flavor changes will make the milk powder become less desirable in the making of other dairy based product. However, according to University of Sydney, Maillard reaction plays such an important role in deterioration during storage of milk powder which it provides advantages function of Maillard reaction in milk powder product. Undesirable Maillard reaction that can occur on milk powder product can be prevented if we take a control in order to prevent this undesirable reaction from occurred such as use lower temperature to reduce the rate of Maillard reaction, control the moisture content where it should below than 0.6 and should exceed 0.7 in order to reduce to mobility of reactant, the pH used also should be maintained in acidic condition as the Maillard reaction is optimum in alkaline condition, and lastly we the used of enzyme and Sulphur dioxide also help to control the Maillard reaction from taking place in milk powder product.

REFERENCES
ADDIN Mendeley Bibliography CSL_BIBLIOGRAPHY Aalaei, K., Rayner, M., & Sjöholm, I. (2018). Chemical methods and techniques to monitor early Maillard reaction in milk products; A review. Critical Reviews in Food Science and Nutrition, 8398, 1–11. https://doi.org/10.1080/10408398.2018.1431202
Copeland, L.(July 28, 2016). The Chemical Reaction That Makes Our Favourite Foods Taste So Good. Retrieved from University of Sydney http://www.australiaplus.com/international/on-the-menu/the-chemical-reaction-that-makes-food-taste-good/7666268
Diego, A., C., Gagneten, M., Leiva, G., & Malec, L. (2017). Antioxidant Activity Developed
at the Different Stages of Maillard Reaction with Milk Proteins, 17, 1-19.
doi:10.1016/j.lwt.2017.11.002
Gonzales, A. S. P., Naranjo, G. B., Leiva, G. E.& Malec, L. S.(January, 2010). Maillard Reaction Kinetics in Milk Powder: Effect of Water Activity at Mild Temperatures. International Dairy Journal,20(1). Retrieved at 13th May 2018 from https://www.sciencedirect.com/science/article/pii/S0958694609001368
Hedegaard, R.,& Skibsted, L.(2013). Shelf-Life of Food Powders. Handbook of Food Powder,409-434. doi:10.1533/9780857098672.2.409
Intipunya, P.& Bhandari, B. R.(2010). Chemical Deterioration and Physical Instability of Food Powders. Technology and Nutrition.

Ledl, F. and Schleicher, E. (1990) The Maillard reaction in foods and in the human body-new results in chemistry, biochemistry and medicine (in German). Angewandte Chemie 102, 597-626.

Mauron, J. (1981) The Maillard reaction in food: a critical review from the nutritional standpoint. Progress in Food Nutrition Sciences 5, 5-35.

Mehta, B. M.& Deeth, H. C.(November 13, 2015). Blocked Lysine in Dairy Products: Formation, Occurrence, Analysis, and Nutritional Implications. Food Science and Food Safety,15(1). Retrieved at 13th May 2018 from https://onlinelibrary.wiley.com/doi/full/10.1111/1541-4337.12178
Newton, A. E., Fairbanks, A. J., Golding, M., Andrewes, P., & Gerrard, J. A. (2012). The role of the Maillard reaction in the formation of flavour compounds in dairy products – not only a deleterious reaction but also a rich source of flavour compounds. Food & Function, 3(12), 1231. https://doi.org/10.1039/c2fo30089c
Nursten, H. E. (1990) Key mechanistic problems posed by the Maillard reaction. In The Maillard Reaction in Food Processing, Human Nutrition and Physiology, eds P. A. Finot, H. Aeschbacher, R. F. Hurrell and R. Liardon, pp. 145- 153. Birkhauser Verlag, Basel.

O’Brien, J. (1995) Heat-induced changes in lactose: isomerization, degradation, Maillard browning. In Heat-induced Changes in Milk, ed. P. F. Fox, pp. 134-170. International Dairy Federation, Brussels.

Pearce, K. N. (n.d.). Dairy Milk Powder. Retrieved from https://nzic.org.nz/ChemProcesses/dairy/3C.pdf
Pereyra Gonzales, A. S., Naranjo, G. B., Leiva, G. E., ; Malec, L. S. (2010). Maillard reaction kinetics in milk powder: Effect of water activity at mild temperatures. International Dairy Journal, 20(1), 40–45. https://doi.org/10.1016/j.idairyj.2009.07.007
Shimamura, T., ; Uke, H. (2012). Maillard Reaction in Milk – Effect of Heat Treatment. In Milk Protein. InTech. https://doi.org/10.5772/50079
Van Boekel, M. A. J. S. (1998). Effect of heating on Maillard reactions in milk. Food Chemistry, 62(4), 403–414. https://doi.org/10.1016/S0308-8146(98)00075-2