Powder Technology 239 (2013) 86–93

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Effect of packaging material on storage ability of mango milk powder and the qualityof reconstituted mango milk drink

Anil Kumar Chauhan ⁎, Vaibhav PatilCentre of Food Science and Technology, Banaras Hindu University, Varanasi-221005, India

⁎ Corresponding author. Tel.: +91 9450658188; fax:E-mail address: dranilchauhan@rediffmail.com (A.K.

0032-5910/$ – see front matter © 2013 Elsevier B.V. Allhttp://dx.doi.org/10.1016/j.powtec.2013.01.055

a b s t r a c t

a r t i c l e i n f o

Article history:Received 28 August 2012Received in revised form 23 January 2013Accepted 26 January 2013Available online 1 February 2013

Keywords:Shelf lifeMango milk powderStoragePackagingProducts

Mango milk powder (MMP) was obtained after recirculatory convective drying, conditioning and grinding.The physico-chemical characteristics of fresh canned mango pulp and those of the finished product wereestimated. The microbiological quality of the beverage showed the presence of low number of cfu (colonyforming unit) as 2.5×103 and ymc (yeast and mold count) as 3 per gram. The product was free from coliformbacteria. MMP was packaged in pouches of high density polystyrene, tin can, metalized polyesters and fourply laminates polythene aluminum foil–polythene–paper. The shelf life of mango milk powder was predictedon the basis of free flowability of product under controlled storage condition and was found to be maximumin tin containers (10 and 11 months, respectively) at 30±1 °C and 5±1 °C.

© 2013 Elsevier B.V. All rights reserved.

1. Introduction

Packaging means placing a commodity into a protective wrapperor container for transport or storage. Package has three fold functionsof containing, protecting and merchandising. It provides protection tothe product against contamination or loss and damage or degradationdue to microbial action, exposure to heat, light, moisture and oxygen,evaporation, etc. It also helps in selling the products. It constitutes animportant link between themanufacturer and ultimate consumer for thesafe delivery of the product through different stages of production, stor-age, transport, distribution and marketing. Mango pulp is the most uti-lized part for human consumption. This portion constitutes about 58 to77% of the total fruit weight depending upon the variety. Prevention ofcancer and heart diseases is possible by antioxidants (β-carotene andvitamin C) rich mango. Bioflavonoid present in mango help in buildinghuman immune system. The insoluble dietary fiber found abundantlyin mango helps in the elimination of waste from the colon and preventsconstipation.

Mango milk shake is reported to be helpful in body weight gainespecially in low weight persons. Mangoes may be used in a varietyof preparations with milk forming as the base, viz., mango milk bever-ages, puddings, custards, ice creams etc. The availability of fresh milkand canned mango is abundant. Manufacture of mango milk powderwill provide an alternate pathway for utilization of surplusmilk solids.The specialty product, so manufactured, is likely to prove highly re-munerative for industry and nutritious for all classes of consumers.

+91 542 2368993.Chauhan).

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Standardization of manufacturing technology of mango milk powder(MMP) and type of packing material may affect the quality and safetyof reconstituted drink. Therefore, evaluation of packaging materialsfor MMP and its reconstituted drink at different storage conditionhad undertaken mainly the fulfillment of the consumer demand fornutritional products with assurance of quality and safety.

New methods of processing and packaging being developed tomeet the growing demand of ready to eat convenience food productswith long shelf stability, nutritional integrity and safety assurance.There is an increasing demand in the world for instant powderwhich could be reconstitute into variety of products.

The present investigation has been planned with the objective toevaluate the suitability of certain packaging material and methods ofpackaging material on shelf of mango milk powder. The packages werepasteurized, dried and filled with inert gases, keeping in view theMetal can, 4-ply laminates (polyethylene-aluminium foil–polyethylene–paper), metalized polyester, polystyrene packages were used.

2. Materials and methods

2.1. Mango milk powder

The mangomilk powder (MMP) (Fig. 1) prepared was used for thepresent study. Standardization of spray drying process for mangomilk powder was done with reference to optimum total solid con-centration, inlet and outlet air temperature and speed atomizationkeeping the flow rate of the feed constant [1]. The ratio of mango(Totapari) pulp, pasteurized toned milk (Vita brand, 3% fat and 8.5%SNF) and refined cane sugar (ISI Mark) was kept constant at 30, 62and 8%, respectively. Concentrated toned milk and one third of total

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Packaging Material

Storage Period (months)

Flowability (q)

Wettability (sec)

Solubiliy (ml)

Bulk Density (g/ml)

Sinkability 2 min

Sinkability 4 min

Sinkability 6 min

Fig. 1. Effect of different packaging materials on physical properties of mango milk powder stored at 30±1 °C. (For interpretation of the references to color in this figure legend, thereader is referred to the web version of the article.)

87A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

sugar were preheated to 70–75 °C and double stage homogenized at1000/500 psi. The homogenized mix was pasteurized followed bycooling to 20 °C and mixing of canned mango pulp with pasteurizedformulation. This mixture was spray dried with operating conditionsof 185 °C inlet air temperature and an outlet temperature objective ofabout 85 °C. The resulting product moisture content was about 2.15%.The atomizer speed of 15000 rpm was used to maintain a constantflow rate with droplet size of about 250 μm. Spray dried product wascollected and dry blended with the remaining two thirds of powderedcane sugar. The resultant mango milk powder (MMP) blend was col-lected in polyethylene lined powder bags. The bags were closed andsealed with a minimum headspace, then allowed to cool at room tem-perature before refilling into the different packaging material used inthe study. Samples of MMP were tested at regular intervals of every2 months up to 8 months and thereafter at monthly intervals up to12 months. Fresh samples of MMP and those stored in different pack-ages were reconstituted with 4.5 times its weight of potable water ina mixer. Chemical analysis of MMB was carried out by the methods de-scribed [2] for total solids, crude fiber content, total sugar and vitamin C.Total soluble solids of MMB were detected by hand refractometer at20±0.5 °C and viscosity was determined by a programmable coaxidcylinder viscometer with digital display (Controvac Rheomat 108 E/RMettle Tolebo, Switzerland) with measuring system 1, 1 for MMB.Flow curve was obtained for shear at range of 100 to 1000 s−1 at20 °C.MMPwas analyzed.Moisture by ISI [3]methods, titratable acidityby AOAC [4], total protein by micro-Kjeldahl methods by AOAC [5] andtotal ash and fat contents as per ISI methods were described [6].

Fully ripe mangoes of the three selected varieties viz. Baneshan (BE),Suvarnarekha (SR), Totapuri (TT) were washed thoroughly, peeled andcut into pieces and stones were removed manually. The cut pieces werefed into the pulper with a sieve size of 1/1600. The extracted pulp washeated at 60 °C in steam jacketed kettle for 3 min, cooled and potassiummetabisulphate was added at the rate of 0.2%. The pulp was then trans-ferred to white high density polyethylene (HDPE) cans and kept in coldstorage until use (less than a month) as per the procedure described [7].

Conventional types of mango products have been developed to aconsiderable extent but the mango industry is eager to develop newprocessed products [8].

2.2. Microbiological analysis

Total viable count and yeast and mold count were done followingthe ISI methods mentioned [6] whereas spore count was done as per

the procedure. Color of reconstitutedMMBwas estimated by LABmodelightness for white (L), greenness and redness (a) and yellowness andblueness (b).

2.3. Physical analysis of MMP

Bulk density and flowability [9], solubility index [3], wettability[10], and sinkability [11] were determined as per prescribed methods.

2.3.1. Bulk densityA 100 ml graduated cylinder of tarred weight was taken. Themouth

of cylinder and the powder was allowed to flow freely to 100 ml mark.The net weight was obtained and results expressed as g/ml (loosedensity). The packed bulk densitywas determined by tapping the cylin-der till the volume attained a constant level. The volume occupied wasnoted and result expressed as g/ml.

2.3.2. FlowabilityA plastic funnel with a narrow stem, cut at right angles, was

mounted exactly 2 cm above a piece of butter paper positioned on ahorizontal table. A sieve with 16-mesh size was fixed to a shaker(100 shakings per minute). Powder sample was placed on the sieveand allowed to go through the funnel in a fine stream at a controlledspeed, so as to form a conical heap. When the top of the powder heaptouched the end of funnel stem, the powder stream was stopped byswitching off the shaker. The base of the powder heap was outlinedwith a pencil and powder was removed. After removing the powder,the outlined paper circle was cut and weighed. The radius was calcu-lated and the angle of repose was estimated.

Tan θ ¼ h= r−1=2 a

� �

Where,

θ angle of repose,h height of stem base (2 mm),r radius of the base of powder heap, anda diameter of funnel stem.

2.3.3. Solubility indexFourteen grams of the powder was reconstituted in a 100 ml of

distilled water. The sediment obtained from 50 ml by centrifugation

Table 1Effect of different packaging materials on physical properties of mango milk powder stored at 30±1 °C.

Packaging material Storage period(months)

Flowability(θ)

Wettability(s)

Solubility(ml)

Bulk density(g/ml)

Sinkability

2 min 4 min 6 min

Initial 58.50 31.20 0.97 0.70 24.33 18.33 14.23Tin can 2 58.50 31.90 0.97 0.70 24.77 18.57 14.50

4 60.20 33.10 1.05 0.72 25.27 18.90 15.336 61.40 35.10 1.25 0.73 26.87 19.00 15.838 62.10 35.50 1.40 0.75 28.79 21.30 17.20

Metalized polyester 2 58.90 31.60 0.97 0.71 24.50 18.60 14.674 60.00 34.50 1.20 0.73 26.43 20.57 17.806 61.20 36.90 1.42 0.75 28.33 22.50 18.778 63.90 39.10 1.62 0.77 30.93 24.63 20.87

4-Ply laminates 2 59.10 31.80 0.97 0.72 24.63 18.80 14.834 60.60 34.30 1.20 0.73 26.87 20.37 17.206 61.30 36.40 1.41 0.73 28.67 22.50 18.438 63.95 39.00 1.65 0.77 30.30 24.30 20.53

Polystyrene 2 59.40 31.70 0.99 0.78 25.37 19.43 15.404 62.80 35.20 1.67 0.82 28.87 23.50 18.636 64.10 39.30 1.80 0.86 30.00 24.17 20.508 65.6 42.2 1.90 0.89 32.00 25.00 21.50

SEM 0.10 0.10 0.03 0.01 0.10 0.10 0.10CD (5%) 0.29 0.29 0.08 0.03 0.29 0.29 0.29

Number of replicates=3.CD=critical difference.SEM=standard error mean.

88 A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

of reconstituted product was measured and results expressed inmilliliters.

2.3.4. WettabilityA piece of satin-fabric measuring 10×10 cm was stretched over

one end of the metallic can (open at both ends with 6.5 cm dia and4.5 cm height) and fastened in position by a rubber band. Anotherone end can (5 cm dia and 7 cm height) was placed centrally onthe cloth. The tray was filled with distilled water at 40±1 °C to aheight of 2.5 cm. A triangle made out of 0.4 cm thick glass rod withsides measuring 8 cm long was placed in the dish and served to pre-vent close contact of the cloth with the bottom of the dish. With thetwo cans assembled, and cloth resting on outer can, 1 g of powderwas transferred to the inner can and spread over the 6 cm circle

Table 2Effect of different packaging materials on physical properties of mango milk powder stored

Packaging material Storage period(months)

Flowability(θ)

Wettability(s)

Initial 58.50 31.20Tin can 2 58.90 31.40

4 60.10 32.806 61.00 34.708 62.10 36.10

Metalized polyester 2 58.80 32.404 62.80 33.106 63.70 36.608 62.90 37.90

4-Ply laminates 2 59.00 31.704 60.30 33.006 62.00 36.408 62.95 37.90

Polystyrene 2 59.30 33.504 61.60 35.006 63.90 38.808 65.00 41.00

SEM 0.10 0.10CD (5%) 0.29 0.29

Number of replicates=3.CD=critical difference.SEM=standard error mean.

of the cloth as evenly as possible with a soft sable hair brush. Theinner can was then removed and the outer can lowered into the trayonto the glass triangle and held in place, until the water level in thecan ceased to rise. A stopwatchwas clicked as soon as the cloth touchedthe water and stopped when the powder got completely wet. The timetaken for complete wetting of powder was recorded in seconds.

2.3.5. SinkabilityIn this test, 3.5 ml of distilled water at 20 °C was taken in the spec-

trophotometer cuvette and 10 mg sample of powder was then dustedon the surface of water and the percentage transmittance was mea-sured at 760 nm in a spectrophotometer. The readings were recordedafter 2, 4 and 6 min intervals. The mean of three replicate values wastaken as the percentage transmittance.

at 5±1 °C.

Solubility(ml)

Bulk density(g/ml)

Sinkability

2 min 4 min 6 min

0.97 0.70 24.27 18.33 14.230.97 0.70 24.23 18.11 14.251.03 0.72 24.64 18.76 15.061.20 0.72 25.09 18.93 15.591.40 0.73 26.66 21.05 17.020.97 0.71 24.41 18.55 14.591.30 0.73 25.35 19.45 16.721.40 0.74 26.11 20.39 17.691.52 0.74 27.79 22.51 18.680.97 0.71 24.43 18.59 14.611.20 0.73 25.38 19.47 16.741.38 0.73 26.15 20.41 17.681.48 0.74 27.82 22.56 18.690.98 0.77 25.22 19.23 15.161.21 0.79 28.79 23.15 18.231.69 0.82 29.75 23.98 19.971.80 0.86 30.50 24.5 24.550.01 0.01 0.10 0.10 0.100.03 0.03 0.29 0.29 0.29

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Packaging Material

Storage Period (months)

Flowability (q)

Wettability (sec)

Solubility (ml)

Bulk Density (g/ml)

Sinkability 2 min

Sinkability 4 min

Sinkability 6 min

Fig. 2. Effect of different packaging materials on physical properties of mango milk powder stored at 5±1 °C. (For interpretation of the references to color in this figure legend, thereader is referred to the web version of the article.)

89A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

Sediment in reconstitutedMMBwasmeasured byfilling reconstitutedMMB in 100 ml cylinder and level was brought up to 100 ml mark.The sediment at the bottomwasmeasured in milliliters after keepingovernights in refrigerator. A digital pH meter (LAB India InstrumentsPvt. Ltd., Mumbai) was used for measuring pH of the reconstitutedMMP at 30 °C.

A panel comprising seven trained judges did sensory evaluation offresh MMB and reconstituted MMB by using 9-points hedonic scalescorecard.

2.4. Storage of powder

The samples of MMP were separately packaged in tin, 4-ply lami-nates, polystyrene and metalized polystyrene and stored at 30±1 °C

Table 3Effect of different packaging materials on microbiology of mango milk powder stored at 30

30±1 °C

Packaging material Storage period (months) cfu×103 YMC×101 Spore cou

Initial 16.0 6.0 12.0

Tin can 2 12.2 4.9 11.64 9.5 3.0 9.56 8.1 2.5 9.28 7.3 1.1 7.1

Metalized polyester 2 12.0 5.1 11.24 9.2 4.0 9.86 7.8 2.1 7.88 6.0 1.2 5.0

4-Ply laminates 2 12.0 5.0 11.64 9.1 3.9 9.46 8.0 2.1 8.68 6.9 1.0 6.6

Polystyrene 2 11.0 5.1 11.84 9.2 4.0 11.26 7.0 2.0 9.28 6.7 0.7 10.4

SEM 0.10 0.10 0.10CD (5%) 0.29 0.28 0.29

Number of replicates=3.CD=critical difference.SEM=standard error mean.

and 5±1 °C for storage studies. The mango pulps were stored withhigher levels of sulfur dioxide [12]. With additional packing such asbag-in-box (a polyethylene pouch placed in a cardboard box) or thealuminium laminated high-density polyethylene, the loss of b-carotenecan be further reduced.

Baneshan, Suvarnarekha varieties showed that the results of mangopowders can be safely stored in metalized polyester/polyester polypackaging for a period of up to 6 months. For storage beyond 6 monthsadditional packaging may be required [13].

2.5. Statistical analysis

Statistical analysis was done by using factorial randomized designof ANOVA. The one factor with four levels that is tin containers,

±1 °C and at 5±1 °C.

5±1 °C

nt×101 Storage period (months) cfu×103 YMC×101 Spore count×101

Initial 16.0 6.0 12.0

2 12.4 5.0 11.84 9.8 3.1 11.16 8.4 2.8 9.88 7.6 1.2 8.24 9.3 4.2 11.36 7.9 2.4 10.18 6.9 1.3 8.42 12.0 5.1 11.66 8.2 2.2 8.68 7.0 1.1 6.72 11.2 5.1 11.84 9.4 4.0 11.32 11.2 5.1 11.84 9.4 4.0 11.36 8.0 2.2 10.18 6.8 0.9 9.40

0.10 0.10 0.100.29 0.28 0.29

90 A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

metalized polyester, 4-ply laminates and polystyrene containers alsosecond factor with 4 levels that is 2, 4, 6 and 8 months. Critical differ-ence (CD) is the least significance difference, greater than which allthe differences are significant. The data for each parameter were col-lected in three replicates. The statistical analysis shows that the effectof different packaging materials and the effect of storage period onphysical properties of mango milk powder were stored at 30±1 °Cand at 5±1 °C.

3. Results and discussion

3.1. Comparative assessment of packaging materials for mango milkpowder

The packaging material and storage temperature are known to in-fluence the physical, chemical, microbiological and sensory propertiesof dried milk products. The selection criteria of a suitable packagingmaterial for mango milk powder was essentially based on the shelflife. The suitability of the packaging materials on quality of mangomilk powder during storage are presented and discussed below.

(a)

(b)

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Packaging Material Tin can Metallized polyester 4-Pl

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Tin can Metallized polyester 4-Ply Laminates Polystyr

Fig. 3. (a) Effect of different packaging materials on microbiology of mango milk powder stmilk powder stored at 5±1 °C. (For interpretation of the references to color in this figure

3.2. Chemical properties

Moisture, acidity, fat, protein and ash content in MMP stored at30±1 °C and 5±1 °C have been presented in Tables 1 and 2 respec-tively. Comparative value of constituents during storage showed about0.41% increase in moisture content over a period of six-month storageat 30 °C in the sample of mango milk powder packaged in polystyrene.Samples packed in 4-ply laminates showed an increase of moisture toabout 0.21% in 6 months.

These results are consistent with those reported by Ardito et al.and Mrithyunjaya and Bhanumurthi [14,15]. It is difficult to ascertainwhether the slight increase in moisture percentage in the sampleswas due to ingress of moisture or the chemical changes occurringduring storage. However, there is a gradual increase in moisture con-tent in dried whole milk during storage.

Titratable acidity showed a minor increase during the storageirrespective of packaging used, suggesting the interplay of variousconstituents and resulting chemical changes. A gradual decrease inpH value was noted during storage. Increasing moisture levels causeda slight reduction in total protein content in the sample during stor-age. There was no change in protein content during storage on dry

y Laminates Polystyrene

30 ± 1°C

cfu

YMC

Spore

Count

ene

5 ± 1°C Storage Period (months)

5 ± 1°C cfu

5 ± 1°C YMC

5 ± 1°C Spore Count

ored at 30±1 °C. (b) Effect of different packaging materials on microbiology of mangolegend, the reader is referred to the web version of the article.)

Table 4Effect of different packaging materials on physico-chemical properties of reconstitutedmango milk powder stored at 30±1 °C.

Packagingmaterial

Storage period(months)

Total solids(%)

pH Color Sediments(ml)

L a b

Initial 19.78 6.05 70.10 8.01 42.23 5.08Tin can 2 19.76 6.01 70.12 8.01 42.17 5.10

4 19.78 5.97 70.25 8.02 42.14 5.166 19.74 5.82 70.25 8.02 42.07 5.308 19.75 5.75 70.28 8.04 41.99 5.42

Metalizedpolyester

2 19.75 5.99 70.27 8.03 42.10 5.114 19.77 5.86 70.28 8.04 42.05 5.206 19.79 5.63 70.36 8.07 41.95 5.418 19.78 5.59 70.41 8.08 41.86 5.72

4-Plylaminates

2 19.76 5.98 70.28 8.04 42.11 5.114 19.78 5.87 70.28 8.04 42.06 5.206 19.77 5.65 70.36 8.07 41.95 5.428 19.77 5.60 70.42 8.08 41.87 5.75

Polystyrene 2 19.79 5.92 70.32 8.06 42.08 5.144 19.77 5.68 70.37 8.07 41.98 5.676 19.78 5.45 70.45 8.09 41.88 5.808 19.8 5.32 70.52 8.11 41.88 5.96

SEM 0.10 0.11 0.10 0.11 0.11 0.10CD (5%) 0.29 0.30 0.29 0.30 0.31 0.29

Number of replicates=3.CD=critical difference.SEM=standard error mean.

Table 5Effect of different packaging materials on physico-chemical properties of reconstitutedmango milk powder stored at 5±1 °C.

PackagingMaterial

Storage Period(months)

Total solids(%)

pH Color Sediments(mg)

L a b

Initial 19.78 6.05 70.10 8.01 42.23 5.08Tin can 2 19.79 6.03 70.20 8.01 42.19 5.08

4 19.78 5.99 70.21 8.02 42.18 5.116 19.76 5.87 70.24 8.03 42.15 5.208 19.77 5.81 70.29 8.04 42.11 5.40

Metalizedpolyester

2 19.77 6.01 70.23 8.02 42.14 5.094 19.78 5.93 70.25 8.03 42.11 5.306 19.78 5.87 70.31 8.05 42.07 5.408 19.76 5.76 70.35 8.07 42.01 5.52

4-Plylaminates

2 19.78 6.02 70.22 8.02 42.13 5.094 19.79 5.92 70.25 8.02 42.12 5.206 19.76 5.88 70.30 8.04 42.07 5.388 19.77 5.77 70.35 8.06 42.02 5.48

Polystyrene 2 19.77 5.95 70.29 8.04 42.05 5.114 19.77 5.71 70.34 8.05 42.01 5.316 19.78 5.52 70.42 8.07 41.93 5.708 19.78 5.37 70.45 8.09 41.82 4.92

SEM 0.10 9.90 0.10 0.10 0.10 0.10CD (5%) 0.29 28.51 0.29 0.29 0.29 0.29

Number of replicates=3.CD=critical difference.SEM=standard error mean.

91A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

matter basis. These results are consistent with those reported byFurukava and Yamamanaka [16], in kulfimix powder titratable acidityincreased over a period of 8 months storage at 30 °C when packed inthe different kinds of packaging materials.

Irrespective of type of packaging material, chemical changes oc-curred faster at 30 °C than those at 5 °C. These results are consistentwith those reported by Driscoll [17], chemical deterioration in milkpowders was faster at 21 °C at temperature of storage than at 10 °C.Increase in fat content with storage periods with corresponding in-crease in moisture may be due to liberation of fat from lipo-proteincomplexes in MMP. Ash content is nearly constant. However, slightdecrease in protein content may be owing to its degradation withcorresponding changes in moisture. Mango pulp carbohydrates andlactose content in MMP have not been estimated and their contribu-tion to acidity during storage may be the contributing factors.

3.3. Physical properties

The effect of packaging materials on physical properties of mangomilk powder is presented in Tables 1 and 2 and Figs. 1 and 2. It can benoted that there was a gradual loss of solubility, flowability, wettabil-ity, whereas, bulk density and sinkability increased during storage at30 °C. The losses in flowability, wettability and solubility were fasterin samples packed in polystyrene than those in metalized polyester,4-ply laminates and tin cans. These results are consistent with thosereported by Pijanowski [18], an increase in amount of free fat mightbe responsible for the loss in wettability and flowability and inverserelation between free fat and wettability.

The increase in wetting time of MMP samples during storage maybe attributed partly to increase in free fat content and native qualityof proteins. Considerable increase in wetting time of dried milksattributed this to increased liberation of free fat during storage[19,20]. Loss in wettability in pre-term infant formula, khoa powderand kulfi mix powder after storage at 30 °C has been reported [21].Besides, similar observationshave also been reported in cheddar cheese,whey powder, whey based mushroom soup powder and whey kinnowjuice powder, respectively [22,23].

A progressive increase in solubility index of MMPmay be attributedto the formation of water insoluble compounds caused by increasedcasein micelles size due to hydrogen bonding [24] consequent toprotein–protein interactions or sugar–protein interaction [25]. Thechanges in protein structure due to Maillard reaction and protein–protein interaction during storage could be responsible for the lossof solubility [26]. Gradual increase in solubility index from 1.07 to1.80 ml in WMP after storage for 6 months at 30 °C is reported byMrithyunjaya and Bhanumurthi [15]. Solubility index of khoa pow-der [21] and kulfi mix powder also increased from 1.2 to 2.0 mlover a period of 8 months storage at 30 °C; in similar studies ondried milks [16,27,28] an increase in solubility index with the prog-ress of storage time is also observed.

Bulk density of mango milk powder increased with the storageperiod irrespective of packaging materials used. Increase in bulk den-sity with increased moisture content was also observed [29] in driedmilk powder and ice-cream mix powder, respectively. An increasein bulk density may be attributed to increased cohesiveness causedby absorption of moisture during storage. Sinkability of mango milkpowder increased with the storage period. Changes occurred fasterat 30 °C than those at 5 °C.

Flowability decreased with increasing storage period more so athigher temperatures. Irrespective of storage temperatures, samplespacked in polystyrene registered a high loss of flowability duringstorage. Angle of repose (tan θ) increased from 62.93 to 66.16 inspray dried malted milk food on storage at 30 °C for 12 months. Agradual loss of flowability in lactose hydrolyzed infant formula onstorage at 30 °C for 12 months. These results are consistent withthose reported by Peleg [30]; increase in free fat content and changes

in particle structure due to moisture absorption during storage couldincrease cohesiveness of powder leading to reduction in flowability.Moist powder exhibited higher angle of repose (mainly due to cohesion),despite the fact that the angle of internal friction usually decreases withincrease in moisture level.

3.4. Microbiological quality

The microbial counts in fresh mango milk powder were SPC16.0×103, YMC 6.0×101 and spore count 12.0×101 per gram ofproduct. The microbial counts largely depend upon the quality ofraw materials used in the product preparation and the methods ofprocessing. The type of package and temperature of storage showedsignificant influence on the growth and survival of microorganisms

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Packaging Material

Storage Period (months)

Total Solids (%)

pH

Colour

Sediments (mg)

Fig. 4. Effect of different packaging materials on physico-chemical properties of reconstituted mango milk powder stored at 30±1 °C. (For interpretation of the references to colorin this figure legend, the reader is referred to the web version of the article.)

92 A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

in mango milk powder (Table 3 and Fig. 3). While yeast and moldcounts decreased rapidly during storage, spores exhibited a great re-sistance. The death rate of bacteria was slower at 5 °C than at 30 °C.Low water activity in the product coupled with antibacterial natureof some of the chemical compounds released in various degradationreactions may have caused rapid destruction of microbial cells duringstorage [31]. As the rate of chemical reactions is slow at lowertemperatures of storage, the decline in microbial number was foundto be slow. A decrease in microbial counts from initial numbers of4.1×103 to 2.2×103 was also reported [32] in SMP after storage for6 months at 30 °C.

The spore counts in MMP showed insignificant decrease duringstorage at 30 °C and 5 °C. Spores survive even in most adverse condi-tions [33]. An insignificant reduction in spore count from an initialnumber of 4.5×102 to 4.0×102 in high heat SMP after storage for6 months at 30 °C is observed by Muir et al. [32].

The YMC also showed a declining trend during the entire storageperiod, becoming almost negligible at the end of storage study bothat 30 °C and 5 °C. Yeast and mold grow at aw above 0.6. Lower aw

-10

0

10

20

30

40

50

60

70

80

1 2 3 4 5 6 7 8 9 10 11 12

Fig. 5. Effect of different packaging materials on physico-chemical properties of reconstitutethis figure legend, the reader is referred to the web version of the article.)

should be one reason for the accelerated death of yeast and moldduring storage. These results are consistent with those reported byRanganadham [21].

3.5. Sensory quality

Packaging material and temperature of storage had marked influ-ence on the sensory quality of mango milk powder. Mango milk sam-ples packed in polystyrene were acceptable up to 150 days of storageat 30 °C and 5 °C. The 4-ply laminates containers and metalized poly-ester offered almost equal storage quality to the product. Sampleswere acceptable up to 8 months of storage at 30 °C and for 9 monthsat 5 °C. Among the four packaging materials studied. Tin cans offeredthe highest protection against loss in sensory scores of mango milkpowder. The samples packed in tin cans were acceptable up to8 months of storage at 30 °C and for 8 months at 5 °C. On the basisof above results, it could be recommended that tin cans are most use-ful for long storage of MMP.

13 14 15 16 17 18

Packaging Material

Storage Period (months)

Total Solids (%)

pH

Colour

Colour

Colour

Sediments (mg)

d mango milk powder stored at 5±1 °C. (For interpretation of the references to color in

93A.K. Chauhan, V. Patil / Powder Technology 239 (2013) 86–93

3.6. Physico-chemical properties of reconstituted mango milk drink

Fresh samples of MMP and those stored in different package werereconstituted with of 4.5 times its weights potable water in mixer.

The stored dried mango milk powder samples were reconstitutedafter every 2 months of storage up to 8 months. The physico-chemicalproperties of reconstituted mango milk drink (RMMD) are presentedin Tables 4 and 5 and Figs. 4 and 5. The pH of mango milk drinkreconstituted frommangomilk powder decreasedwith advancing stor-age period. The change in pH was faster in samples packed in polysty-rene containers than those in metalized polyester, 4-ply laminates andtins. These results are consistent with those reported by Ranganadham[21]; amino groups of protein get blocked in the Maillard reaction lead-ing to decreased pH. Therewas an increase in l and a value and decreasein b value for color in reconstituted mango milk drink. Change in coloroccurred faster at 30 °C than that a 5 °C.

3.7. Sensory quality of reconstituted mango milk beverage

The sensory score of mango milk drink prepared from storedreconstituted MMP was significantly different from those of the sam-ples prepared from fresh MMP.

These results are consistent with those reported by Radayevam et al.[34]; the flavor scores of reconstituted mango milk drink decreasedsteadily with the progress of storage period. The rate of deteriorationwas faster at 30 °C than at 5 °C. The rate of deterioration was slightlyfaster in samples packed in polystyrene than those packed in metalizedpolyester, 4-ply laminates and tins. The rapid decline in flavor scoresafter 5 months storage could be expected due to oxidative changes.

The body and texture score also decreased with increased storageperiod. There was a steady reduction in color and appearance scoresof mango milk prepared from progressively stored MMP. Reductionin color and appearance may be due to oxidation of pigments.

The statistical analysis has shown that tin can has significant differ-ence as compared to other packaging material because the differencebetween the mean value of tin can and other treatment is more thanthe critical difference (CD) value.

4. Conclusion

It is concluded that mango milk powder packed in tin containers,metalized polyester, 4-ply laminates and polystyrene containers canbe preserved for 2, 4, 6 and 8 months at 30 °C and at 5 °C respectively.Therefore, the most suitable packaging material for long storage ofMMP is tin can, whereas the least suitable materials is polystyreneunder both the temperature conditions studied. This shelf life wasachieved without addition of any preservative or antioxidant.

References

[1] C.G. Hill, An Introduction to Chemical Engineering Kinetics and Reactor Design,John Wiley and Sons Publication, New York, 1977.

[2] S. Ranganna, Handbook of Analysis and Quality Control for Fruit and VegetableProducts, 2nd ed. Tata McGraw Hill Publications Co Ltd. Replika Press Pvt Ltd.,Delhi, 2001.

[3] ISI, Handbook of Food Analysis, Dairy Products Part-XI Indian Standards InstitutionManak Bhavan New Delhi India, 1981.

[4] AOAC, Official Methods of Analysis, Association of Official Analytical Chemist,Washington DC, 1995.

[5] AOAC, Official Methods of Analysis, 16th ed., Association of Official AnalyticalChemist, Washington DC, 1970.

[6] SP:18 (Part-XI), ISI Handbook of Food Analysis, Dairy Products Indian StandardsInstitution Manak Bhavan New Delhi India, 1981.

[7] D. Amba, P.G. Adsule, Bulk Preservation ofMango Pulp in High Density Polyethylene(HDPE) Containers, Indian Food Packer, Nov–Dec 1979, pp. 34–37.

[8] M. Hassan, J. Ahmed, Physico-chemical and Sensory Characteristics of Mango-MilkBeverage, Indian Food Packer, March–April 1998, pp. 32–36.

[9] A. Sjollema, Some investigations on the free flowing properties and porosity ofmilk powders, Neth Milk and Dairy Journal 17 (1963) 245–253.

[10] M.M. Muers, M.A. House, A simple method for comparing the wettability ofinstant spray dried separated milk powders, XVI International Dairy Congress B,1962, pp. 923–930.

[11] E. Sammhammer, A method for measuring instant properties of milk powder,Milchwissenschaft 21 (1966) 413.

[12] D.V. Sudhakar, S.B. Maini, Stability of carotenoids during storage of mango pulp,Journal of Food Science and Technology 31 (1994) 228–230.

[13] T.V. Hymavathi, V. Khader, Carotene, ascorbic acid and sugar content of vacuumdehydrated ripe mango powders stored in flexible packaging material, Journalof Food Composition and Analysis 18 (2005) 181–192.

[14] E.F.G. Ardito, L.F.C. Madi, S.A. Ortiz, R.M. Solar, J.L. Farah, E.E.M. Mori, D.D. Alvin, I.Delazari, I. Shirose, Stability of dried skim milk, Boletin do Instituto de Techlogiade Alimentos (Brazil) (17) (1980) 205.

[15] N. Mrithyunjaya, J.L. Bhanumurthi, Shelf life of laminate and tin packed wholemilk powder, Indian Journal of Dairy Sciences 40 (1987) 78–85.

[16] N. Furukava, Yamamanaka, Changes in dried milk during storage. Study of proteindenaturation of sephadex G-150 gel filtration, Journal of Agricultural SciencesJapan 16 (3/4) (1972) 218–225.

[17] N.R. Driscoll, C.P. Brennad, D.G. Hendricks, Sensory quality of non-fat milk afterlong term storage, Journal of Dairy Science 68 (1985) 7931–7942.

[18] E. Pijanowski, S. Zmarlicki, D. Nowak, T. Zoladek, Wettability of dried whole milkand its content of free fat, Nahrung 18 (1974) 753–761.

[19] V.P. Kuznetsov, Study of the characteristics of rapid solubility of dried milkduring storage, Trudy Vseoyuznyi Nauchno-issledovated Skill Insitute Molochnoipromyshlennosti (49) (1979) 27–28.

[20] R. Labztily, T.T. Tran, T. Bekes, F. Rekakasi, Change in the free fat content of driedmilksand other milk based products during storage, Elemiszervizsgalati kozlemenyek 26(4/5) (1980) 123, (cited: Dairy Science Abstract (43) (1980) 8648–8649).

[21] M. Ranganadham, Process innovation in the manufacture of Khoa Powder, JournalAgricultural Issues 1 (1) (1988) 45–54.

[22] H.M. Jayaprakasha, Membrane processing application for production of wheyprotein concentrates, PhD Thesis NDRI Karnal India (1992).

[23] K. Khamrui, Development of technology for concentrated and dried whey basedfruit juice mixes, PhD Thesis NDRI Karnal India (2000).

[24] N. King, The physical structure of dried milk—review, Dairy Science Abstract 14(1965) 151–159.

[25] Sat Prakash, Some recent views on reconstitutability and keeping quality of milkpowder, Journal Milk and Food Technology 32 (1969) 183–192.

[26] Z. Segena Colos, Industrial manufacture of low lactose dried milk, Anales de laFaculted de Ciencias Quimicas Y Farma Chile, 1979.

[27] G.K. Jensen, P.S. Hanson, The influencing of packaging and storage temperatureon the reconstitutability of infant whole milk powder, 20th International DairyCongress, 8, 1978, pp. 730–731.

[28] F.G. Kieseker, P.T. Clarke, The effect storage on the properties of non fatmilk powders,Australian Journal of Dairy Technology 39 (1984) 74–83.

[29] D. Kerekreti, Regulation of moisture, bulk density, particle size and wettability ofdried milk, Prumysl Potravin 31 (1980) 327–334.

[30] M. Peleg, Effect of conditions on the flow properties of powdered sucrose, powdertechnology, in: M. Peleg, E.B. Bagley (Eds.), Physical Properties of Foods, 7, TheAVI Publishing Co Inc., Westport Connecticut USA, 1977, p. 45.

[31] R.C.D. Lara, S.E. Gilliland, Growth inhibition of microorganisms in refrigeratedmilk by added Maillard reaction product, Journal of Food Protection (48)(1980) 138–147.

[32] D.D. Muir, M.W. Griffiths, J.D. Phillips, A.W.M. Sweetsur, I.G. West, Effect of bacterialquality and some properties of low heat and high heat dried milk, Journal SocietyDairy technology 39 (1986) 115.

[33] R.K. Robinson, Modern dairy technology, Advances in Milk Processing, vol. 2,Elsevier Applied Science Publishers, London, 1986.

[34] I.A. Radayevam, L.S. Dmitrieva, E.A. Bekhova, The effect of added antioxidants onkeeping quality and on phospholipids functions of whole milk powder, 19thInternational Dairy Congress IE, 1974, pp. 618–627.