food safety unit - department of health and human services

Fermentation

Gabrielle Allen - Senior Food Science Officer

Food Safety Unit - Department of Health and Human

Services, Victoria

Today’s topics

What is fermentation

What is fermented

Where do we find fermented foods

Food safety of fermented food and drink

Pub quiz

SCOBY

Pub quiz

Oenophobia

The return of tradition

http://www.penn.museum/blog/collection/125th-anniversary-object-of-the-day/7000-year-old-wine-jar-object-of-the-day-24/

Foodborne illness incidence

Food Country Year Sick Deaths Pathogen Cause

Home pickled turshi (middle

eastern fermented vegetables)

US 2013 4 0 C. botulinum Unsatisfactory fermentation

Pruno (prison alcohol) US 2011 8 0 C. botulinum Untested recipe. Potato added increasing

pH allowing C. botulinum to grow.

Pruno US 2016 26 C. botulinum

Tofu US C. botulinum bulk tofu which had been kept

unrefrigerated, uncovered, and in water-

filled bins

Home-canned pickled vegetables US 2016 1 C. botulinum

Seal flipper US 2015 4

Beaver tail US 2016 1 C. botulinum

Fermented blackbeans (douchi) China 2014 139 0 B. cereus Unsatisfactory fermentation

Kimchi – raddish and cabbage

variants

Korea 2012 1642 0 E. coli 0169

Hazelnut yoghurt UK 1989 27 1 C. botulinum Contaminated hazelnut conserve

Salami and metwurst AUS 1995 150 + 1 E. coli and

Salmonella

Traceability, back sloping etc etc

Source: Barblog

Foodborne illness incidence

Food Country Year Sick Death

s

Pathogen Cause

Fresh garlic in oil US 36 0 C. botulinum Unsatisfactory acidification, anaerobic

conditions

Olives Italy 2016 Unknown 1 C. botulinum

Semi dried tomatoes AUS 2009 140 Hepatitis a processing expired tomatoes

Fermented seal flipper US (Alaska) 3 0 C. botulinum Change of process, creating anaerobic

conditions

Home pickled tomatoes Azerbaijan 2015 8 1 C. botulinum Unsatisfactory fermentation

Home preserved mushrooms in oil Italy 1998 1 1 C. botulinum Unsatisfactory acidification, anaerobic

conditions

Olives Finland 2011 2 0 C. botulinum Process failure

Source: Barblog

What has changed?

So if the principles and processes are the same, and there are few instances

of foodborne illness, why are we worried about food safety?

• supply chain

• wider distribution

• industrialisation

• consumer expectation, in regards to rigorous food safety systems

• increase of cottage industries in recent years – Masterchefitis

• breakdown in the generation to generation knowledge exchange, loss of

knowledge

• changes to traditional processes

• changes to traditional recipes

Skinned seal flippers ready to be fermented. Note the

plastic rubbish bin bag. Image: NativeTech.

A manufacturer of wine…

Activity 1: Changes in traditional processesBotulism from fermented seal flipper…

Skinned seal flippers ready to be fermented

Image: NativeTech.

Activity 2: Changes in traditional recipes

A manufacturer of wine… Image barfflog

Botulism from drinking pruno (otherwise known as

prison wine, jailhouse hooch, juice, or brew)…

Why do we ferment food?

• flavour development

• nutritive value

• preservation (pH control for food safety)

What is fermentation?

Fermented food and beverages undergo a microbial

process, where yeasts, bacteria or moulds degrade

or break them down into by-products.

What is fermentation?

Sugar becomes alcohol

and acid (beer, wine)

Sugar becomes food acid

(yoghurt, sauerkraut/kimchi, kombucha)

Alcohol becomes food acid

(vinegar)

Source: Fermentation and food safety. Martin R Adams, MJ Robert Nout

Different types of fermentations

Activity 3 - Back to school

The products – the diversity of fermentation

The products – the diversity of fermentation

Worldwide: alcohol, wine, vinegar, olives, yogurt, bread, cheese

Asia

• East and Southeast Asia: amazake, atchara, bai-ming, belacan, burong mangga, com

ruou, dalok, doenjang, douchi, jeruk, lambanog, kimchi, kombucha, leppet-so, narezushi,miang, miso, nata de coco, nata de

pina, natto, naw-mai-dong, oncom, pak-siam-dong, paw-tsaynob, prahok, ruou nep, sake, seokbakji, soju, soy sauce, stinky

tofu, szechwan cabbage, tai-tan tsoi, chiraki, tape, tempeh, totkal kimchi, yen tsai, zha cai

• Central Asia: kumis (mare milk), kefir, shubat (camel milk)

• South Asia: achar, appam, dosa, dhokla, dahi (yogurt), idli, kaanji, mixed pickle, ngari, hawaichaar, jaand (rice

beer), sinki, tongba, paneer

Africa: fermented millet porridge, garri, hibiscus seed, hot pepper sauce, injera, lamoun

makbouss, laxoox, mauoloh, msir, mslalla, oilseed, ogi, ogili, ogiri, iru

Americas: sourdough bread, cultured milk, chicha, elderberry wine, kombucha, pickling (pickled

vegetables), sauerkraut, lupin seed, oilseed, chocolate, vanilla, tabasco, tibicos, pulque, mikyuk (fermented bowhead whale)

Middle East: kushuk, lamoun makbouss, mekhalel, torshi, boza

Europe: rakfisk, sauerkraut, pickled cucumber, surströmming, mead, elderberry wine, salami, sucuk, prosciutto, cultured

milk products such as quark, kefir, filmjölk, crème fraîche,smetana, skyr, rakı, tupí.

Oceania: poi, kaanga pirau (rotten corn), sago

What about pickles?

Quiz question one – How do acids act as preservatives?

1. By cooking the food

2. By stopping or slowing the growth of food poisoning and

spoilage bacteria

3. By providing anaerobic conditions

4. By making the food taste nice

Answer - Food acids act as preservatives by reducing the food’s pH and thus

stopping or slowing the growth of many food poisoning and spoilage bacteria.

Quiz question three – Which food poisoning bacteria is the most significant concern for acidified foods?

1. Escherichia coli

2. Clostridium botulinum

3. Bacillus cereus

4. Salmonella

Answer - Clostridium botulinum

Quiz question two – What pH limits the growth of Clostridium botulinum?

1. 7.01

2. 4.6

3. 10.3

4. 4.2

Answer - The risk of Clostridium botulinum spores germinating and producing

toxins is increased if the pH is above pH 4.6. pH can rise as it equalises with the

product, a stating pH of 4.2 is recommended to account for this.

Quiz question five – Are all food poisoning bacteria limited by pH 4.6?

1. Yes

2. No

Answer - Some microorganisms are more acid tolerant than others

Bacterial pathogens of concern in acidified products –acid tolerance

Limits for Growth of Some Common Bacterial Pathogens


Food safety threats – not just microorganisms


Food acid alone is not enough for adequate food safety

Key barriers in preventing food borne diseases in many cases are:

• good manufacturing practices (GMP),

• a robust hazard analysis and control process food safety program

and

• good hygiene practices (GHP)

Food acid alone is not enough for adequate food safety - hurdles

Food safety in acidification and fermentation specifically relies on:

•good quality undamaged raw materials

•contamination prevention (before, during and after processing)

•well controlled fermentation processes

Food safety steps and examples of suitable parameters

Good quality undamaged raw materials

• trusted raw materials suppliers

• removing dirt and bacteria from raw produce by washing produce

in potable water, or removing contaminated outer leaves or

skins

• heat treatment, to eliminate competing bacteria prior to

acidification, such as using pasteurised milk for making yoghurt


Contamination prevention

• good hygiene practices (such as handwashing)

• cleaning and sanitising procedures


Well controlled fermentation processes

• use a proven recipe

• accurately follow recipe each time

• the correct fermentation temperature

• refrigeration of finished product

• heat treatment (where appropriate) of finished product

• addition of other ingredients such as salt

Food acid alone is not enough for adequate food safety - hurdles

Ingredients and processes that can be used in combination

with acid are:

• salt and/or sugar

• preservatives (additives such as sorbic acid, benzoic acid)

• heat treatment

• refrigeration

Some examples of the fermentation process

Sauerkraut

1. Preparation of raw materials

2. Core, trim and shred

3. Fermentation process

Anaerobic

Temp 18-22 ºC for 2-6 weeks

Salt 1.0 to 3.5 (typically 2.25) % wwInoculate, if using

4. Pack


Yoghurt Heat pasteurised milk to eliminate

competitive flora and cool 30-32 ºC

Fermentation process

Temp 30-40 ºC for 6-20 hours

Pack and refrigerate

Inoculate

Cool

Fermented soft drinks


Kombucha Boil water and steep tea


Temp 18 – 26 ºC for 10 – 14

days

Sugar

Inoculate with starter

culture (SCOBY -

for symbiotic colony

of bacteria and yeast)

Sweeten and flavour


Cool

Spoilers…….

Proportion of drinks compliant with the Code – national survey

Spoilers…….

Multiple factors influence the alcohol content of

brewed soft drink

These include:

• drink type

• shelf life

• secondary fermentation

• flavouring

• temperature

• measurement

Group discussion

Where, in your role as an EHO, might you find products that have

been fermented?

Activity 4: Spot the ferment

Bistro Blackwood – Rundle Street Adelaide

The pot by Emma McCaskill - Hyde Park

94º West, Findon

The flying fig - North Adelaide

Assessing skills and knowledge

Assessing skills and knowledge - the key points

How are they controlling pH?

Is the pH under 4.6?

How are they controlling alcohol?

Activity 5 Assessing skills and knowledg - what questions should you ask your fermented food producer?

• Sauerkraut

• Yoghurt

• Kombucha


Sauerkraut

Similar products – kimchi, dill pickles, cornichons

1. Preparation of raw materials

2. Core, trim and shred

3. Fermentation process

Anaerobic

Temp 18-22 ºC for 2-6 weeks

Salt 1.0 to 3.5 (typically 2.25) % wwInoculate, if using

4. Pack


Yoghurt Heat pasteurised milk to eliminate

competitive flora and cool 30-32 ºC


Temp 30-40 ºC for 6-20 hours


Inoculate

Cool


Kombucha Boil water and steep tea


Temp 18 – 26 ºC for 10 – 14

days

Sugar

Inoculate with starter

culture (SCOBY -

for symbiotic colony

of bacteria and yeast)

Sweeten and flavour


Cool

Key questions

How do you make your product?

What is the pH of your product?

How are you controlling the alcohol?

Health claims

Health claims - note that these apply to both labels and advertisements

It is the businesses responsibility to make sure health claims are compliant with

the approved conditions in Schedule 3 of Standard 1.2.7 Nutrition, health and

related claims, or meet the requirement of providing a body of evidence to

substantiate general level health claims.

pH measurement and meter calibration

pH and acidity

pH is the strength of an acid in the sample

Acidity is the amount of acid in a sample, or the amount of

base required to neutralize a sample.

Litmus paper

Advantages

1. no calibration

2. inexpensive

3. simple

Disadvantages

1. sample colour interference

2. precision

3. accuracy

Methods to measure pH

Methods to measure pH continued

pH meter - meter with electrode

Advantages

• precision

• diversity of design and application

• accuracy

• $ to $$$

Disadvantages

• calibration

• complexity

• cleaning and storage

pH meters. What should EHOs look for?

• calibration solutions

• cleaning solutions

• storage solutions

How often do you calibrate your meter?

Are they in date? When were they opened?

Is the probe cleaned regularly?

How is the probe stored?

Measurement technique

• rinse between samples with water

• fully immerse Junction

• stir the sample

• wait for stabilisation

• consistent sample temperature

Measurement method

Sample slurry Direct measurement Liquid and solids

Key points for accurate readings

• calibration

• measurement technique

• cleaning routine

• storage routine

food safety unit - department of health and human services

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