Particle Characterization of Food Formulations€¦ · Milk also contains casein micelles, which...

© 2020 Malvern Panalytical Com

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Particle Characterization of Food FormulationsDr Stephen Ward-Smith


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A competitive industry!

• Thousands of food products are launched each year, but only 20 – 30% will be successful.

• Consumers have a clear understanding of what they like (China has limited interest in chocolate). Parts are fast-moving, and manufacturers try to adopt the latest trends.

• Expectations are high.

• The formulation scientist has to deliver a product that performs, that will be enjoyed, that will be stable and that will be purchased again.

January 19, 20202


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Global consumer trends in food and beverage

• Clear & clean labeling, reduced packaging• Transparency in package labeling, micro/nanoplastics

• ‘Free from’ platforms• Demands for meat-, gluten- and dairy-free

• ‘Flexitarian’ effect• ‘Part-time vegetarians’ for health, sustainability and animal

welfare concerns• Natural processing

• Negative perceptions of heavily-processed food• Green light for vegetables

• Hidden vegetable products; rise of fusion smoothies and high vegetable pastas


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A variety of end applications with common challengesDepending on product and formulation, the customer could be concerned with:

• Stability• Phase separation• Settling• Consistency• Creaming• Pumpability• Flowability• Mouthfeel (and other sensory characteristics)• Shelf life• Clouding, clearing, fining, clarifying• Grinding (and other particle reduction methods)• Fraud/ingredient quality

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Most products we use daily have been designed by scientists to ‘work’

• So many of the products we use have been developed by a team of scientists to perform in a certain way.

• We encounter so many particle systems on a daily basis, and take for granted the effort that has been put into making them work.

• A formulated product is not a ‘bad’ product.


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Which particle properties of food are important?

Particle size Particle size distribution Particle shapeComposition

Mechanical Charge / stability

Microstructure


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Dairy Formulations


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Homogenization

StabilityMineral content

Dairy formulations

19 January 20208

Frequently used technologies

Compositionanalysis


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Dairy formulations

• Milk is homogenized to improve its shelf-life• This reduces the fat globule particle size from 1 -15 µm in unprocessed milk to 1-2 µm in homogenized milk

• Smaller globules reduce creaming, increasing the milk’s shelf-life

• Milk also contains casein micelles, which aid fat globule stabilization after homogenization• Monitoring the fat globule size and the proportion of free casein micelles is important during homogenization

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Monitoring the homogenization process

Homogenized milk is an oil-in-water emulsion containing:

• Fat globules (1 µm - 2 µm)• Casein micelles (0.05 µm - 0.25 µm)• Lactose • Whey proteins• Vitamins and minerals (low concentration, typically 5g/L)

The fat globules and casein micelles contribute to the particle size distribution measured by laser diffraction. The lactose, whey, vitamins and minerals are all present in solution and so do not contribute.


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Dairy formulations

• Analysis of 3 UK milk samples with different fat contents

• The of fat globule proportion, measured as the volume percentage above 0.25 µm, increases with the total fat content of the milk

• Casein micelles form the remainder of the population

• The largest particles are present in the whole milk, which has the highest fat content

• The smallest particles are present in the skimmed milk, which contains only a trace of fat

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Measuring casein micelles and fat globules in milk


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Dairy formulations: milk powder

• “Quality and safety are the foundations of social harmony”• Poster at one of the Chinese companies tainting milk - if only they had

practiced what they preached!• 6 infant fatalities, 54,000 hospitalizations• 2 people executed• One CEO received life imprisonment

• Government encouraged milk consumption.• Demand exceeded supply• new small suppliers were brought in and corners were cut!• Melamine ‘imitates’ protein content

• Elemental analysis of milk powder is a key XRF application• Fortification is another key application – track added extras (Malted

milk drinks, protein shakes)

January 19, 202011

Milk powder contamination: 2008 Chinese infant formula scandal


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Dairy: milk powder

• Milk powder was measured as pressed pellets• Measurement time only 10 minutes• Na, Mg, P, Cl, K, Ca, Mn, Fe, Cu, Zn were analyzed

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XRF analysis of mineral content in milk powder


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Emulsions, flavors & additives


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Formulation

Stability

Molecular/ Structural

Characterization

Food additives

19 January 202014

Frequently used technologies

Elemental composition screening


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Food Additives

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• Additives can be divided into several groups. • Some additives have more than one effect; e.g. salt is a

preservative and a flavoring.

• Anticaking agents keep powders such as milk powder from caking or sticking• Antifoaming and foaming agents control of air bubble formation• Antioxidants e.g. Vitamin C preserve food by inhibiting degradation by oxygen• Bulking agents e.g. starch increase food bulk without affecting its taste• Food colorings replace colors lost in preparation, or make products more attractive• Emulsifiers allow water and oils to remain mixed together in an emulsion.• Flavors natural or artificial ingredient that give a particular taste or smell• Preservatives prevent or inhibit food spoilage by microbes• Stabilizers, thickeners and gelling agents add texture and aid stabilization• Sweeteners are added to foods for flavoring and added consumer appeal• Thickeners increase product viscosity without substantially modifying other properties


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Food Additives

• Maltodextrin is derived from starch by enzymatic or acid degradation• Used in a variety of food applications; e.g., sports drinks, energy bars• Material is bought based on its bulk viscosity

• 3 samples analyzed: all have similar viscosity but end properties are different• Can we identify any structural differences that explain this?

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Case study: Grading food additives

RIVISCLALS

10.0 12.0 14.0 16.0 18.0 20.00

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Retention Volume (mL)

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RIVISCLALS

10.0 12.0 14.0 16.0 18.0 20.00

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RIVISCLALS

10.0 12.0 14.0 16.0 18.0 20.00

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RIVISCLALS

10.0 12.0 14.0 16.0 18.0 20.00

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Food Additives

• All samples have a similar Intrinsic Viscosity

• Sample A shows:• Considerably higher molecular weights• Higher density at lower molecular weights

• Same IV but different molecular weight implies very different structural properties• Suggests enzymatic degradation is incomplete for

Sample A, despite appropriate bulk viscosity

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Case study: Grading food additives

ABC

3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00-1.50

-1.20

-0.90

-0.60

-0.30

Log(Molecular Weight)

Log[

Intri

nsic

Visc

osity

]

A B CMw (D) 468,300 189,700 66,310Mn (D) 134,600 42,400 25,130

IV (dl/g) 0.1173 0.1149 0.0929Radius (nm) 10.88 8.23 5.55

Mark-Houwink plot

Sheet1

ABC

Mw (D)468,300189,70066,310

Mn (D)134,60042,40025,130

IV (dl/g)0.11730.11490.0929

Radius (nm)10.888.235.55

Sheet2

Sheet3


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Food Additives

• Zeta potential analysis can identify long term stability issues

• Large particles can lead to a ‘greasy’ appearance

January 19, 202018

Color emulsion particle size analysis by Laser Diffraction


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Mouthfeel/milling


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The tongue as a particle size analyzer

• The tongue can detect particles >30 micron - anything smaller tastes smooth• Anything bigger can taste greasy or gritty• This can be perceived as a ‘quality’ issue: US chocolate mouthfeel is not popular in Europe

• Smaller particles start to clump• Increased surface area,

greater interaction, caking, etc.

January 19, 202020

And other size-related issues…


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Chocolate

• Gritty chocolate containing particles greater than 30mm in size is considered poor quality;• Producing too many fine particles during milling can cause problems with processing and

controlling the chocolate phase behaviour.• Over-milling the chocolate components increases production costs as more cocoa butter needs to

be added to obtain the right mouthfeel;• Cocoa butter costs up to U$4000/ton• Over-milling to produce finer product shown below could increase production costs by up to $2.8M/Y

Food Sector Itroduction21

Particle size control during milling

Standard chocolate(Dv90 = 28µm)

Finer milled chocolate(Dv90 = 24µm)


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Conclusions

• Hopefully provided a brief introduction into how size, shape, elemental composition and charge are useful measurands that can help the formulation scientist develop a pleasing product for todays markets

January 19, 2020Title of the presentation22


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www.malvernpanalytical.com

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Thank you for your attention

Particle Characterization of Food FormulationsA competitive industry!Global consumer trends in food and beverageA variety of end applications with �common challengesMost products we use daily have been designed by scientists to ‘work’Which particle properties of food are important?Dairy FormulationsDairy formulationsDairy formulationsDairy formulationsDairy formulations: milk powderDairy: milk powderEmulsions, flavors & additivesFood additivesFood Additives Food AdditivesFood AdditivesFood AdditivesMouthfeel/millingThe tongue as a particle size analyzerChocolateConclusionsThank you for your attention

Particle Characterization of Food Formulations€¦ · Milk also contains casein micelles, which...

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