TA3004. Food Packaging

Transcription

1 TA3004. Food Packaging Lesson 4: Glass Packaging Materials M.S. Ashanty Miguel Piña Rodriguez Module 2: Food Packaging Materials Campus Queretaro Spring 2012

2 Objectives To learn how glass is made for packaging purposes To learn about the different types and uses of glass containers To learn basic processes of manufacturing glass containers

3 Glass Packaging Attributes No permeability to gases, water vapor and liquids Chemically inert and compatible Hygienic, easy to wash and sterilize Easy to tint to protect product from UV rays Adequate mechanical resistance for filling and stacking Resistant to high internal pressure Reheatable (in microwave)

4 GRAS status by USDA Product inside stays colder for longer Premium image Transparent, or colored Multishape, rigid material Reusable and 100% recyclable No loss in quality and purity Recycling one glass bottle saves energy for: A 60-watt bulb (four hours) A computer (30 minutes) A tv (20 minutes)

5 Glass Characteristics Liquid (molecular structure) Unique material Solid (physical properties) Glassy structure Progressively more rigid when temperature is reduced

6 So, What IS Glass? Main ingredients: Sand Soda Ash Limestone Cullet Sand Hardest to melt Small particle size, very fine grains ( mesh size) The other materials depend on sand s specifications Cullet Improves efficiency (energy/furnaces)

7 Typical Glass Composition (Source:

8 Colorizing Glass By adding small quantities of: Chromium (for green) Cobalt (for blue) Nickel (for violet/brown) Selenium metal (for red) Iron (amber) Sulfur (amber) Reasons: Appearance tell apart Protect product from UV rays

9 Corrosion Etching Alkaline attack Destroys silica network Leaching Acid attack Weathering Not well understood, takes centuries to show Mild: surface bloom because of extended storage conditions

10 Most aggressive solution for glass Double distilled water (ph 7) Most food products have an acidic aqueous phase Diluted acidic solution are much less aggressive Replacement of sodium ions by hydrogen ions

11 Mechanical Resistance Failure = fracture Stress concentrator + tensile stress Breakage causes Internal pressure Carbonated drinks, hot processing Mechanical impacts Moving container contacting a stationary object Moving object contacting a stationary container Vertical load strength High speed filling and sealing Scratches and abrasions Reduced by surface treatments Thermal shock Cooling of container resulting in temperature differences

12 Thermal Properties Thermal shock Pasteurization process Heavier glass = higher mechanical resistance = lower thermal resistance Fig. Stress on the inside and outside surfaces of a round glass Source: Robertson, 2006

13 Manufacturing Process In essence, the same for bottles and jars Large equipment, >700 bottles per minute Watch video carefully

14 Important Pieces in the Manufacturing Process

15 Manufacturing Process Mixing and Melting Forming Process Surface Treatment Annealing

16 Gob Formation and Shapes Gob specific amount of molten glass An optimum gob shape for each glass container Gob length and diameter depends on the desired final container Overall size considerations: Weight: ½ oz. to 48 oz. Length: ½ inch to 6 inches Diameter: 3/8 of an inch to 4 inches A 7 oz. gob is typical for a 12 oz. beer bottle. (Source:

17 Blow and Blow Process Typically for bottle making (Source: Emhart Glass SA,

18 Wide Mouth Press and Blow Process Typically for jars making (diameter 38mm and larger) (Source: Emhart Glass SA,

19 Narrow Neck Press and Blow Process Typically for beverage bottles (diameter 38mm and smaller) (Source: Emhart Glass SA,

20 Surface Treatments Two general types: Hot-End 550 C, thin unimolecular film of metal oxide (tin or titanium). Strengthens and improves adhesion of second coating. Cold-End <100 C, spraying an organic aqueous solution (waxes, stearates, silicones, oleic acid or PE) Protects surface and increases lubricity

21 Glass Container Three basic parts: Finish Body Neck Shoulder Heel Bottom Fig. Glass container nomenclature. Source: Robertson, 2006

22

23 Defects in Glass Containers 60 different defects can occur Classification Critical If hazardous to the user, and container is completely unusable i.e. bird-swings, spikes Major If usability is reduced (container or content) Minor If detracts from appearance or acceptability to the consumer i.e. wavy appearance

24 Chip (minor) Stone in glass (minor) Pitted area (minor) Sagging surface (minor) Thin spot (major) Check (major) Pitted rust (major) Bead (major) Blister (major) Bird swing (critical) Leaker (critical)

25 Thin bottom, Thin neck, bird swing, inclusion, thin spots also in non round,: every change in glass thickness is detected with infra red. (source:

26 Breakage of Glass Containers Based on cause of break Internal pressure Usually midway of the container Impact Radial forking occurs Thermal shock Difference in temperature (Source: Food containers,

27 Capping a Bottle Glass containers can be resealable Closure: cap, lid, cork or plug Functions: Hermetic seal Easy to open and reseal Evidence of tampering Materials: Metal: tin, ECCS, aluminum Plastic: phenolic-formaldehyde resins, PS, PE (LD/HD), PP, PVC

28 Closure Parts Panel Radius/Shoulder Skirt Smooth Knurled Fluted Lug Gasket/liner Rubber or PVC Liners (wad) Composition cork, paperboard, and coated

29 Closures for Food Products To retain internal pressure Crown caps/cork Roll-on tamper-evident To contain and protect content Bark cork Stelvin

30 To maintain vacuum inside container Lug-type or twist cap Press-on and twist-off cap Pry-off (side seal) cap To secure contents inside container Screw caps

31 Shrinking Sleeves Extra protection & marketing Marketing as a label Added protection Plastic films that shrink with heat Two type Thin, foamed PS Thermal insulation Uniaxially oriented PVC or PS Contains glass fragments if bottle is dropped

32 Consumer Preference Leading packaging material for products: Preference for Glass by Categories True flavor Purity Quality Shelf life (Source: GPI May 2006)

33 Disadvantages Weight High ratio packaging weight/product weight Storage Lower stacking compression resistance Careful transport Safety issues related to handling Quality inspection of recycled containers Washing containers Physical evaluation Inappropriate previous use Relatively higher cost