Dairy Products 2
Yoghurt
A webinar presented by:
Dr Andy Bowles
Attendee Notes 07/04/2020
Dairy Products 2 Yoghurt
1
This webinar will consider
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
2
This webinar will consider
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
3
1 07/04/2020
Introduction
Most common fermented milks: Yoghurt Kefir
4
Yoghurt - Codex definitions
Yoghurt: Symbiotic cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.
5
Kefir - Codex definition
Starter culture prepared from kefir grains: Lactobacillus kefiri, Leuconostoc spp, Lactococcus spp and Acetobacter spp.
Grains contain yeasts: lactose fermenting Kluyveromyces marxianus non-lactose-fermenting Saccharomyces unisporus, Saccharomyces cerevisiae and Saccharomyces exiguus.
6
2 07/04/2020
Factors affecting quality of yoghurt
Choice of milk Milk composition Additives Homogenisation Heat treatment Choice of culture Process flow
7
Choice of milk
High quality milk Free from: Antibiotics Bacteriophages Residues
8
Milk composition
Fat 0 – 10% Typical 3.5%
Solids not Fat (SNF) Increased by skim milk powder, whey, lactose
9
3 07/04/2020
Additives
Common other ingredients: Sweeteners Stabilisers Flavourings and colours Fruit and other ingredients
10
Homogenisation/heat treatment
Effect of homogenisation pressure and heat treatment on viscosity of fermented milk 35
30
25
20
15 Viscosity
10
5
0 0 7.5 15 30 Pressure MPa
Past Milk High Heat Milk
11
Choice of culture
Commercially available Frozen Freeze dried
Influence Taste Mouthfeel Acidity
12
4 07/04/2020
Process flow
Product influenced by Nature Order of process.
13
Yoghurt
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
14
Yoghurt – typical process
Milk for yogurt production pasteurised: 85°C for 30 mins 95°C for 10 mins
High temperatures used: To allow starter culture to work Coagulation of whey proteins Enhanced viscosity and texture
15
5 07/04/2020
Yoghurt – typical process
Milk commonly homogenised to stabilise components. Starter culture added
16
Yoghurt – typical process
Starter culture = LB + ST When used together, produce rapid acidity Fermentation ensues producing: Lactic acid Acetic acid Acetaldehyde
17
Yoghurt – typical process
Temperature maintained at 43°C for 4-6hrs When titratable acidity + 0.85-0.90% Cooled to 5-22°C, agitated Fruit etc added Packaged
18
6 07/04/2020
Yoghurt
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
19
Types of yoghurt
Main types Stirred yoghurt: incubated in tanks and cooled before packing, Set yoghurt: incubated and cooled in the package. Drinking yoghurt: Coagulum is broken down to a liquid before being packed, Frozen yoghurt: incubated in tanks and frozen like ice cream Greek yoghurt or strained yoghurt: incubated in tanks, concentrated and cooled before packed.
20
Stirred yoghurt
Incubation Treated milk + culture 42-43˚C 4 – 5 hours Incubation Cooling 15 - 22˚C Cooling Stops acid development Flavouring Flavouring Heat treated fruit
Packing
21
7 07/04/2020
Set yoghurt
Incubated in pack Treated milk + culture Rapidly cooled Flavouring
Packing
Incubation
Cool
22
Drinking yoghurt
Low viscosity Reduced SNF Milk + culture Stabiliser added pectin Incubation
mixing
Heat treatment
Packing
23
Frozen yoghurt
Commonly: Milk/Mix/Culture Mix yoghurt with ice cream mix Incubation Ferment ice cream mix
Freezing
Packing
Hardening
24
8 07/04/2020
Greek yoghurt/strained yoghurt
SNF increased Skim milk + culture After fermentation
Drain whey Incubation
Concentration
Mixing
Packing
25
Yoghurt
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
26
(c) ABC Food Safety Ltd
27
9 07/04/2020
(c) ABC Food Safety Ltd 28
(c) ABC Food Safety Ltd
29
30
10 07/04/2020
Yoghurt
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
31
HACCP
Most likely problems Poor management Cooling Incubation Contamination Fruit etc Packaging Packing
32
Summary
Introduction
Typical process
Types of yoghurt
Technology
Common hazards and controls
33
11 07/04/2020
Dr Andy Bowles
www.abcfoodlaw.co.uk @abcfoodlaw 01603 319863
34
12
section V- HACCP-based Plans FERMENTED MILK PRODUCTS
This family of fermented milk products includes kefir, yoghurt, buttermilk, ymer, filmjölk, rjażenka and others - whose common feature is their acidification by lactic acid bacteria. There are two ways of making fermented milk products: 1. Set type method. Milk is mixed with ingredients (sugar, fruits, flavours, colourings etc.) then inoculated with starter cultures, filled into its final packaging before incubation and, finally, cooling. 2. Stirred type method. Milk is inoculated with starter cultures and incubated in a fermentation vessel. When a required pH has been reached, the coagulum is cooled and mixed with ingredients before filling and packing. Depending on the technology used, the producer should determine the exact sequence of steps appropriate to their product.
Process step to Checking/Monitoring Why do we have to be careful? Preventive actions Corrective actions monitor procedure Filling the vat C, M: Contamination of milk by processing Ensure that equipment is always Organoleptic inspection. Repeat cleaning and/or disinfection. equipment and utensils (vats, stirrers, buckets, clean. Never put small pieces of Rinse thoroughly with potable water. scoops etc.) Dirty equipment can cause equipment directly on the floor. Adjust cleaning procedure. If it is a contamination of milk with pathogenic (1) (2) recurrent issue review training of bacteria. Residues of cleaning agents can staff. contaminate milk. Pasteurisation** (3) M: Fermented milk products are very sensitive Provide adequate facilities for Measurement of Re-pasteurise the milk if the required to the development of pathogenic bacteria. pasteurisation. temperature and time. temperature drops below the limit. Some bacteria can survive inadequate Change or improve pasteurisation pasteurisation. equipment. Cooling to M: Possibility of recontamination due to too Ensure quick cooling time using Measurement of Change or improve cooling incubation long cooling time or unsuitable cooling effective cooling equipment. temperature and time. equipment temperature equipment.
Addition of starter M: Contamination of milk during inoculation Use only active starters of Visual inspection: check Reject packs of poor quality, cultures (4) due to poor quality of starter bacteria or known origin or those with a appearance and expiry abnormal appearance and smell. inadequate handling by the production staff. certificate of conformity and date. Adjust handling and storage suitable for food-use. Store and procedures, change the supplier. handle hygienically.
75
section V- HACCP-based Plans FERMENTED MILK PRODUCTS
Process step to Checking/Monitoring Why do we have to be careful? Preventive actions Corrective actions monitor procedure Addition of* fruit, M, C, P: Possibility of contamination Use only tools cleaned and/or Visual and organoleptic Reject ingredients and packaging of colourings, during additions of ingredients. disinfected after each dosing. Use only inspection. suspect quality, abnormal flavourings etc. (5) ingredients obtained from a reputable appearance and smell. supplier or known source and checked upon delivery and before use. Heat-treat Adjust handling and storage herb mixes or fruit where the source and procedures, change the supplier harvesting conditions are not known.
Incubation* M: Acidification if slower than Ensure good technical condition of Visual and organoleptic Reject products with unusual smell expected according to the recipe can process facilities: (incubation vessels inspection and/or taste allow development of harmful or chambers) Maintain appropriate microorganisms. time and temperature, according to Monitoring of Adjust incubation parameters the given technology acidification or pH measurement Generally recommended value: final acidity pH ≤ 4,5
Cooling of the M: Possibility of development of Ensure rapid cooling of the products Measurement of Maintain and/or replace cooling product harmful microorganisms because of temperature and time. equipment long and slow cooling.
Packaging M, C, P: Possibility of contamination Clean and/or disinfect filling and Visual inspection. Reject packages if damaged or of by packaging machines, packaging packaging lines after each use. poor quality, material, production staff or the Keep packages in dry and clean place, packing environment e.g. by airborne protected against pests. Carefully clean Maintain packaging equipment in a fungi. reusable packaging. Minimise air good state of repair. circulation; close doors and windows If it is a recurrent issue review and turn off fans if not required. training of staff. * According to a specific technology, these steps may occur in different order. ** This step is strongly recommended but not compulsory See Also: 1) GHP cleaning. 2) GHP Disinfection 3) HACCP-based Plan Milk Collection, Storage and Treatment. 4) GMP Cultures. 5) GMP Additions to the milk and curd 76