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Masterclass 30 June 2009

Sensory Overload

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General Introduction

Welcome to the Masterclass – Sensory Overload. This information

pack includes introductions to the people who will be working with you today, and summaries of the activities you will participate in. It

also contains important information about how to keep safe during

today’s activities.

Table of Contents PEOPLE INVOLVED 3

SAFETY AND RESPONSIBILITY 4

SENSORY PERCEPTION AND HOW THE SENSES CAN INTERACT 8

MEASURING FOOD FLAVOUR 16

SOIL QUALITY AND EARTHWORM DIVERSITY 22

FURTHER INFORMATION AND LINKS 26

Timetable

Time Activity Location

10.50-11.00 Arrival/Housekeeping/Agenda

11.00-11.20 Mini lecture by Dr Joanne Hort LR9, Food

Sciences

11.20-11.55 Sensory Perception Sensory Suite,

Main Building

11.55-12.30 Measuring Food Flavour APCI-MS Lab,

Food Sciences

12.30-1.15 Lunch Rushcliffe

Restaurant

1.15-2.15 Environment Lab and Field Work Session Teaching Lab, Food Sciences

2.15-2.30 Q & A Session

2.30-3.00 Tour of the Arboretum

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People involved Dr Joanne Hort is Associate Professor in Sensory Science in the Division of

Food Sciences at the University of Nottingham. Initially, she studied Food Technology and began her career in teaching. However, she returned to University to receive her doctorate concerning the modelling of the sensory

attributes of cheese from analytical and instrumental measures in 1998. As a lecturer at Sheffield Hallam University she carried out sensory

consultancy for local industry, developed a sensory program at undergraduate level and oversaw the installation of new sensory facilities

before being appointed as Lecturer in Sensory Science at the University of

Nottingham in 2002. She has since established the University of Nottingham Sensory Science Centre, which is renowned for both its sensory

training and research into flavour perception. She delivers sensory courses at both undergraduate and postgraduate level and is Course Director for the Postgraduate Certificate in Sensory Science. Her research interests

focus on the multimodal aspects of flavour perception and she has published several articles in this area, together with oral presentations and

posters at international Symposia. She is a founder member of the

Professional Food Sensory Group of the Institute of Food Science and Technology and was on the organising committee of the 6th International

Pangborn Symposium in the UK in 2005.

Dr Amy Rogers is postdoc in ecology. She studied for her BA in Natural

Sciences at Cambridge University and then went travelling for a couple of

years, working on research projects in Australia and America. She did a PhD on bird songs at Melbourne University in Australia and then returned to

the UK to work as a secondary school science teacher. Whilst she was

teaching she had the opportunity to go on a scientific expedition to

Antarctica and it made her realise she wanted to do more science outreach. She is now working on an outreach project that aims to encourage people

to go outside and study the environment.

Emily Boothroyd is originally from Leeds, where she completed A levels in

English Literature, Latin, Chemistry and an AS level in Home Economics. She graduated from Northumbria University at Newcastle with a degree in Forensic Science. Her passion for food and flavour led her to embark upon a

PhD in Food Sciences here at the University of Nottingham. Based in Sutton Bonington’s Samworth Flavour Laboratory, she is in her first year of her

PhD research project into the aroma character of malt whisky.

Vicky Whelan is a PhD student in Food Sciences, based at Sutton

Bonington Campus. She is originally from the Wirral and completed A

levels in Biology, Chemistry, Food Technology, General Studies and an AS

level in English Literature. She completed a 4 year undergraduate degree at the University of Nottingham, studying Food Science with European Studies, during which she spent 6 months studying in Valencia, Spain.

After completing her degree she then decided to stay to do a PhD on “the sensory properties of chocolate in different matrices”.

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Safety and Responsibility

We want to make sure your visit to the University of Nottingham is

as safe and interesting as possible. Please read the notes below and,

while on campus today, please ensure you follow all instructions from

your teachers and the researchers leading the activities.

Please be aware of where you and your belongings are at all times.

In every building you visit, you will be told where the nearest

emergency exit is. If you hear an alarm, please make your way

quickly and calmly to the exit.

No bags or coats should be taken into laboratories. In laboratories,

please do not touch any equipment unless you are specifically invited

to do so. You may be asked to wear a lab coat, gloves and/or goggles for some of the activities. If you fail to do so, you will not be

allowed to participate.

If at any point in the day you are injured, you must inform the

researcher you are working with or another member of staff

immediately. Certified First Aiders will be available to help you.

Thank you very much. With your cooperation we can have a safe

and productive day. A full risk assessment has been completed for today’s activities. If you would like to see a copy, please ask.

Laboratory Safety

The laboratories are equipped and run so that with appropriate care,

you can work without risking the health and safety of yourself and

others. Accidents are unexpected or undesirable events, but they

are avoidable with due care and attention.

You have a duty of care to work in a way that will not harm

the health and safety of yourself and/or others.

All experimental procedures are assessed for risks, any necessary

safety measures put in place, and documentary evidence kept. All containers in the laboratory are labelled with their relevant hazards

and any equipment that may present a hazard or needs instruction

before use will carry clear notices.

Ensure that you read any methods before and during the practical

class, listen to instructions from staff and watch carefully any

demonstrations of experimental procedures.

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REMEMBER: Any mishap with a chemical (or apparatus) MUST be

reported to a member of staff IMMEDIATELY so that they can deal with the problem and remove any hazards correctly.

Safety is an integral part of good laboratory practice. Even LOW

HAZARD chemicals may be hazardous if misused. Risks from hazardous chemicals are minimised by handling them correctly.

HAZARDOUS chemicals require careful handling at all times because

of one or more of the following characteristics:

(a) flammability

(b) explosive nature

(c) toxic, hazardous, irritant, etc:

with effects on or through the skin.

with effects on or through the respiratory tract.

with effects on or through the eye.

with effects following ingestion.

(d) reactive with water.

(e) reactive with air. (f) detrimental effect on the environment – especially to

aquatic life.

Containers of hazardous chemicals carry a pictogram indicating the type of danger.

Toxic Highly Flammable Explosive Biological Hazard

Corrosive Harmful, Irritant Oxidising

Ensure that you know how to deal with any spillage BEFORE you embark on an experiment.

Do not ignore the warning signs displayed in the School. They are

there for your protection. The British and European standard safety signs are used:

(Yellow with black border/text)

(Orange with black text)

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Prohibitory Signs: e.g. “No Smoking”, are circular with a

red border and crossbar over a black symbol on a white background.

Warning Signs: e.g. “Caution, risk of ionising radiation”,

are triangular with a black border on a yellow background.

Mandatory Signs: e.g. “Eye Protection”, are circular on a

blue background with symbols in white; used when there is an obligation to wear safety equipment.

Emergency Signs: e.g. “Emergency Shower”, square or rectangular, on a green background with symbols in white.

Fire doors must be kept closed at all times. Know where the fire-

fighting, first-aid equipment, eye-wash and emergency showers are

situated.

Ensure that you know the location of fire exits.

In the event of a FIRE ALARM or an EMERGENCY EVACUATION of the

laboratory, turn off all your equipment as you leave the laboratory

and follow staff to the fire assembly point.

Working Safely in the Masterclass

Before commencing any operation in the laboratory give due care

and attention to how the procedure can be carried out without risk to yourself or fellow workers. If you are in doubt, consult a member of

staff before you start.

• Containers should be opened with caution and away from the face. • Take care not to ingest or breathe in vapours or powders.

• Wear nitrile gloves when handling hazardous chemicals.

• Open wounds, e.g. cuts on hands should be protected by a wound dressing / band aid.

• Turn back over-long cuffs on clothes and laboratory coats to

reduce the chances of knocking over equipment or contaminating

cuffs / sleeves. • Do not put pens / fingers etc in mouths and do not eat or drink

anything, including sweets or gum.

• Do not rub eyes / face with contaminated hands /nitrile gloves.

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• Risks are minimised by working tidily, cleanly and avoiding

spillages. • All spillages must be wiped up immediately.

• Dispose of all products, by-products and surplus chemicals

correctly.

• IF IN DOUBT – ASK • Wash hands at the end of your laboratory session.

Spillages / accidents / FIRST AID • Spillages / splashes on the skin should be rinsed off immediately

with plenty of cold running water, then washed with soap and

warm water.

• Any splashes in the eye(s) should be washed out immediately with

an eye wash bottle and / or with plenty of cold running water.

• All cuts and scrapes on hands should be rinsed with cold running

water.

• Any burns should be held under cold running water for at least 10

minutes.

Seek advice from a member of staff if you have an accident or if you

feel unwell. A trained first aider will give advice, ensure any injuries

are treated and that relevant documentation is completed.

Glassware

• Do not use any glassware that has chips or cracks – hand it to a

member of staff for disposal.

• Take care when rinsing out glassware for reuse or to send for

washing – if there are any chipped edges or cracks – hand to a

member of staff – do not rinse out.

• In the event of breakages, do not pick up the pieces of glass. Ask

a member of staff to sweep up the pieces with a brush and

dustpan.

Risk is associated with glassware, electrical, mechanical and high/low

pressure apparatus. Be aware of potential risks before using any

equipment.

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Sensory perception and how the senses can interact Victoria Whelan

What is sensory analysis?

Sensory analysis is basically getting people to assess things, for example by taste

or smell, or by looking at the appearance of things. They are then asked to give

their opinion about certain aspects. This could be giving their opinion about how

much they like something or whether they think something is sweet enough for example. This type of sensory analysis is commonly associated with consumer

studies when you want to know people’s liking for a product and which product

they prefer.

Alternatively sensory analysis could involve asking people to rate samples for an

attribute or set of attributes. For example they may be rating bitterness and would

give a score out of 10 for how bitter they find the sample to be. In this case they

give no mention about how much they like the sample and instead are purely

rating the sample on a scale for the attribute in question. This involves using

people as an “instrument” to gain information about the samples.

Sensory tests often take place in booths, as you will see today in the sensory suite.

When panellists come to take part in the tests they are asked not to wear perfume or lipstick because this could interfere with their perception. In addition they are

asked not to eat or drink strong foods before attending a panel. These include for

example curries, which could also interfere with their sensory perception. When

they are in the booths they are asked to sit quietly and not discuss the samples

with others because this could change their opinion.

The tests can take place on a computer or can be done on paper. The samples are

provided to the panellists labelled with a 3 digit code, for example 289. This is to

prevent any biased answers. For example presenting samples labelled A, B, C or

1, 2, 3 suggests that there is an order and could affect the way that people assess

the samples, particularly if asked to put them in the order they like them. But

what you want is for them not to be influenced by the label of the sample, so a

random code helps prevent this.

Flavour

Flavour is very important to us because it is what gives us our enjoyment of food.

For this reason flavour is very important to companies, which therefore makes

sensory analysis very important because it tells us what people like and want and

how people perceive a product.

How would you define flavour?

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

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AROMA If your nose is blocked (if you

have a cold) the aroma volatiles can’t interact with the odour receptors – try holding your

nose when you drink the banana solutions – what difference does

it make?

WWhhaatt iiss ffllaavvoouurr?? Flavour is the result of integration of information from our

senses, or modalities, within the brain. All of the modalities are important, not only taste and smell but also

touch/texture, sight and sound.

TASTE Some tastants can increase flavour

intensity when paired with a congruent, or harmonious aroma – try the banana

flavoured drinks and notice the difference between those with and

without sugar

TOUCH/TEXTURE The characteristic mouthfeel of chocolate, the smoothness of ice-cream. Often texture can be similar, try holding your nose when you eat chunks of apple and turnip – can you tell a difference?

SOUND Think about how the sound when you bite into an apple

or a cracker influences perception

SIGHT The sight of a beautifully presented dish can

certainly get us salivating and vision was once considered the overriding sense but would you eat a lovely looking fish if it smelt rancid? Smell

the coloured solutions – can you tell what flavour they are?

Chemesthesis is responsible for the ‘burn’ of chilli peppers, the ‘tingle’ of a fizzy drink and the ‘sting’ of horseradish

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AA mmaatttteerr ooff ttaassttee

((CChhaannddrraasshheekkaarr,, HHoooonn

eett aall.. 22000066))

Non-volatile compounds in food dissolve in saliva and are carried into the taste pore to interact with receptors. The receptors are housed in taste buds

which are located on papillae on the tongue’s surface, the soft palate, pharynx and epiglottis.

Currently thought to be 5 primary tastes; sweet, salty, bitter, sour, and umami.

UUMMAAMMII

SSAALLTTYY

BBIITTTTEERR

SSWWEEEETT

SSOOUURR

‘UMAMI’ means ‘deliciousness’ and is a savoury, meaty taste characterised by foods like

parmesan, dark mushrooms and soy sauce

Did you know? The sense of taste is known as

gustation. We have ~10,000 taste buds and taste cells

regenerate every 2wks or so

Each taste bud contains between 50-150 TRC’s representative of the 5 taste sensations

Did you know? Cats can’t taste ‘sweet’ as they lack part of the sweet receptor

Current research is investigating whether there may be other taste receptors specifically

sensitive to calcium and fat

Many factors can affect taste sensitivity such as composition of saliva, age (no’s of taste buds can

start to decline >60yrs), illness, drugs, genetics, hormones and even

how hungry we are!

We are born with an innate liking for ‘sweet’ and disliking for ‘bitter’. Sweet tasting foods are usually energy rich whilst a bitter taste may indicate toxins. Experience and

learning shape taste preferences.

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Therefore flavour is the combination of all of the senses and you need all of

the information in order to come to a conclusion. For example you might say that

something tastes like banana but it is actually the combination of smell and taste

that makes you come to this conclusion, and if you take away the aroma then you

won’t taste the banana. It has also been shown that if you present banana aroma

without the sugar then you won’t taste the banana. This shows how both aroma

and taste interact to give banana flavour.

Task 1 – Banana Experiment to demonstrate taste-aroma

interactions

You will be presented with 3 banana flavoured samples to taste and you should

follow the protocol and write down what you think about the samples in terms of

how they taste.

Protocol: - 1. Sample 1 (½ of the sample) – Don’t drink all of sample 1 (save some for

later). When you consume the sample pinch the

nose.

After swallowing unpinch the nose.

What did you notice when you had your nose pinched?

__________________________________________________________

What did you notice when you unpinched your nose?

__________________________________________________________

2. Sample 1 (the other ½ of the sample) – Consume the rest of sample 1

Sample 2 – Consume Sample 2 straight after (There is no need to pinch your

nose when consuming this sample).

How did you find this sample?

__________________________________________________________

3. Sample 3 - Consume Sample 3 (There is no need to pinch your nose when

consuming this sample).

How did you find this sample?

__________________________________________________________

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Explanation of the results

Sample 1 (Banana flavour + sugar) – You probably will have noticed that when

you had your nose pinched you couldn’t taste banana but once you unpinched your

nose then you could taste the banana. This is because when you had your nose

pinched, the banana aroma couldn’t get to the receptors in the nose, so you were

relying on taste alone. Once you unpinched the nose then the banana aroma could

get to the receptors in the nose and combined with the taste of sugar, the brain

recognises it as banana flavour. This highlights that the sense of smell is required

in order to taste banana flavour.

Sample 2 (Sugar alone) – You will probably have found that you could still taste

banana. This is because by tasting sample 1 before sample 2, you will still have

banana aroma reaching the nose receptors. And then by having the sugar sample

you have reactivated the brain to recognise the banana flavour. This highlights

how banana flavour is driven by sugar. However, if you waited a while before

tasting sample 2 then you may only taste sugar and not taste banana flavour. This

is because you have no banana flavour to reactivate.

Sample 3 (Banana flavour alone) – You will probably have found that this

sample tasted like water but smelt like banana. This is because there is no sugar

in the sample, and you associate banana flavour with sugar and therefore don’t

recognise banana flavour unless sugar is present. This highlights that we associate

banana flavour as being with sugar because most banana flavoured things that we

all know are sweet. Therefore both sugar and banana flavour need to be present

to taste banana.

Task 2 – Demonstrating Colour-Aroma Interactions

The colour of food is very important to our perception of a foods’ flavour. The

appearance is what provides us with our first impression of the food, so that we

already have a pre-conception of what we think it will be like. It is very difficult to

override this initial idea that we have and if something is flavoured differently to

what the colour suggests then we can get confused and still think that it is the

flavour the appearance suggests. This has been demonstrated with wine, where

white wine that has been coloured red has been described by wine tasters using red wine descriptors because they are expecting it to be red wine.

In this task I hope to highlight how colour impacts on flavour.

You have been provided with 6 different coloured solutions. You need to SMELL

(not taste) each of the samples and write down on the following page what flavour

you think the sample is.

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What flavour do you think the bottles are?

Write what you think in the boxes below.

A

B

C

D

E

F

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Task 3 – Are you a Supertaster???

There are 2 commonly used tests to find out whether you are a non-taster, taster

or supertaster. These are papillae counting and PROP sensitivity testing. Today we are just going to carry out papillae counting to establish an idea of what sort of

taster you are.

If there are many taste buds then it would be expected that you are a supertaster,

which means it would be expected that you would be more susceptible to

bitterness and could dislike bitter foods or spicy foods because they are found to be

too intense for you. Non-tasters would have very few papillae.

How many fungiform papillae can you count?

__________________________________________________

Are you a non-taster, taster or supertaster? __________________________________________________

TThhee ffuunnggiiffoorrmm ppaappiillllaaee aarree

ssmmaallll ppiinnkkiisshh ddoottss.. TThheeyy

hhaavvee tthhee lleeaasstt nnuummbbeerr ooff

ppaappiillllaaee..

TThhee ffuunnggiiffoorrmm ppaappiillllaaee aarree

llaarrggeerr aanndd mmoorree rroouunnddeedd..

TThhee ffuunnggiiffoorrmm ppaappiillllaaee ccoovveerr

tthhee ttoonngguuee aanndd tthheerree aarree

ccrraacckkss ccaauusseedd bbyy lloottss ooff ttaassttee

bbuuddss.. TThheeyy hhaavvee aa ggrreeaatteerr

ddeennssiittyy ooff ttaassttee bbuuddss..

WWHHAATT AARREE YYOOUU?? –– TTAAKKEE TTHHEE TTAASSTTEE TTEESSTT!!

•• PPaappiillllaaee CCoouunntt - Paint the tip of your tongue with blue dye using a cotton bud (not too much!) - Use a mirror to decide if you have few, some or many taste buds (see below).

The pink dots are your fungiform papillae - they don't take up the food colouring. These papillae are the tiny bumps on your tongue that house your taste buds. The more papillae you have, the more taste buds you have and the more sensitive to taste you are. On average, non-tasters have fewer than 15 papillae in this area, while supertasters have over 30.

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What Makes a Supertaster? • Homozygous for the dominant PROP gene (PAV:PAV)

• Taste of PROP is intensely bitter.

• Numerous fungiform papillae

Taster status and diet selection: implications for health • SUPERTASTERS tend to have extreme likes and dislikes. They avoid bitter

tasting foods, such as cruciferous vegetables (like broccoli), which contain

many substances linked to cancer prevention.

• NON-TASTERS eat a wide range of foods and may have increased

acceptance of fat and sweet foods.

Could taster status act as a marker for those at risk of diet related disease?

Some Facts! • Women are more likely to be tasters and are more sensitive to the bitter

taste of PROP than men.

• 25% Caucasians, 10% Asians and 5% Africans are non-tasters.

• All populations currently studied have non-tasters except a small group of

Brazilian Indians.

• The distribution of Non-tasters/Tasters/Supertasters in Western population

is around 25/50/25.

• Children are more sensitive to bitterness, which may explain why they are

more fussy eaters.

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Measuring Food Flavour Emily Boothroyd

What do you think is the difference between flavour and aroma?

Flavour Perception

Have you ever had a bad cold with a blocked nose, and found you

were unable to taste your food? Or pinched your nose to eat something you didn’t like the taste of, only to let go and find that you

could still taste it?

This is because when you eat, volatile compounds from the food you are chewing are released into your nose, where they bind with

olfactory receptors in the nasal membrane. A chemical signal is then

passed on via neurons to the olfactory bulb in the brain. Here the signal is processed and memories are recalled which identify the

smell. This is called retronasal olfaction, because the volatiles travel

from your mouth into the back of the nasal cavity where it is

detected by the receptors.

Depending on their molecular structure, some odour compounds bind

to the olfactory receptors more than others, which results in a

stronger smell, even when the odours may be present at the same

concentration.

Therefore, if we can measure the profile of volatiles which escape

from the nose while eating, we can get a better idea of the actual

flavours being perceived at the time of consumption. In the lab, we do this using a technique called Atmospheric Pressure

Chemical Ionisation Mass Spectrometry or APCI-MS.

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2

4

1 1. Olfactory bulb

2. Olfactory receptors

3. The pathway of

orthonasal olfaction

4. The pathway of

retronasal olfaction

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Atmospheric Pressure Chemical Ionisation Mass Spectrometry

This technique analyses the gaseous phase using the differences

between the masses and charges of ionised molecules to separate

the volatiles present in the sample.

1. Introduction of the sample The sample headspace (the gas phase above a sample) or a person’s

breath is introduced into the inlet port of the machine. The system works under a vacuum, therefore due to the difference in

pressure it is constantly taking in and sampling the volatiles in the

lab air.

2. Ionisation in the Gas Phase: Corona Discharge At atmospheric pressure, the sample is heated and sprayed with a

high flow rate of nitrogen gas to create a cloud of gaseous particles.

The ‘cloud’ then interacts with a corona discharge operating at a high

voltage, creating protonated molecular ions (M+H)+.

3. Analysing the ions: Quadrupole Mass Analyser The quadrupole mass analyser consists of 4 parallel rods with a fixed

electrical current and an alternating frequency applied to them. The ions pass through the centre (as shown below) and, affected by the

electric fields acting upon them, they are detected according to their

mass to charge ratios (m/z).

Sample Introduced

1

2

3

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Other applications of APCI-MS include:

• On-line chemistry – the analysis of cooked flavours

(http://www-

wip.nottingham.ac.uk/biosciences/foodsci/flavour/frg_thermal_

flavour.php)

• Pheromone analysis e.g. parasitic wasps

(http://www.nottingham.ac.uk/biosciences/foodsci/flavour/frg_

research_highlights.php#following)

SNIFFING ACTIVITY: Minty Molecules

Look at the following pairs of compounds.

What differences can you spot between each pair?

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Carvone displays stereoisomerism, which means that the two

molecules (isomers) share both the same molecular formula and

sequence. More specifically, they are enantiomers, which mean they

are complete mirror images and therefore cannot be superimposed

on each other.

With such similar structures, do you think that the pairs will smell

similar?

You will have an opportunity to find out if you are correct when you

smell these compounds during the activity today.

You can write down what they actually smell like in the table below.

Compound Aroma Descriptors

- Menthone

- Menthol

R-(-)-Carvone

S-(+)-Carvone

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CHEWING GUM ACTIVITY: Breath-By-Breath Analysis

Reference samples of each minty compound will be analysed by the

MS for comparison with breath samples.

You will be given the opportunity to have your breath sampled by the

MS while you chew a sweet.

Bearing in mind what we learnt in the sniffing activity, which

compounds do you expect to find in the different sweets?

You will be shown how to interpret the spectra on the screen.

What happens to the level of minty volatiles when the volunteer can

no longer taste the mint flavour of the chewing gum?

What does this tell us about taste-aroma interactions?

Safety:

• The experiments involving sniffing minty aromas use

concentrations similar to those experienced during eating mint sweets to mimic the olfactory experience, hence the levels are

not hazardous.

• Equally the eating of samples and breath analysis has been

approved as a technique by the ethics committee and is not

considered hazardous. The students will have the opportunity

to have their breath sampled whilst eating mints, but, we will

also have demonstrators available in case they do not want to. • Please do not take part if you are aware of any existing illness

or medical condition.

• There is no obligation on anyone to take part and you may

withdraw from an experiment at any time.

• If you have any concerns, or you are not sure whether you

wish to take part, please discuss the matter in confidence with

a member of staff.

Last time you ate some mint

chewing gum do you remember:

a) how long it took to

reach its maximum

minty flavour intensity?

b) how long it took for the

gum to lose its flavour?

Breath-by-breath analysis of flavour

volatiles in orange juice

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References used

Linforth, R.S.T. (2007) Taste and aroma: Why does chewing gum

lose its flavour? Food Flavour Masterclass, University of Nottingham

Linforth, R.S.T. & Taylor, A.J. (1993) Measurement of volatile release

in the mouth. Food Chem. 48 115

Diagrams

Olfactory: http://winearomas.com/images/nose_diagram.jpg

APCI:

http://en.wikipedia.org/wiki/Atmospheric_pressure_chemical_ionizati

on

Mass Quadrupole: http://www.chm.bris.ac.uk/ms/theory/quad-

massspec.html

Menthone & Menthol: Linforth, R.S.T. (2007) Taste and aroma: Why

does chewing gum lose its flavour? Food Flavour Masterclass,

University of Nottingham

Carvone Enantiomers: http://en.wikipedia.org/wiki/Carvone

Breath-By-Breath Analysis of Orange Juice Volatiles: http://www-

wip.nottingham.ac.uk/biosciences/foodsci/flavour/flavour_analyses.p

hp

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Worm Sense

Not all organisms sense the environment in the same way.

In this session you will:

Explore how worms and other invertebrates sense their environment

Use a microscope to examine external earthworm structures

Investigate ways in which earthworm sensory perception impacts

their behaviour and distribution

Carry out a practical to help scientists determine how earthworms

are distributed in the environment

Do you think earthworms can sense things in their

environment?

How do we know if earthworms can sense things?

What do you think they can sense?

How do you think that earthworms sense things?

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Up Close and Personal

Please don’t touch the specimens with your fingers. Use the forceps

or gloves provided.

Place the worm on a petri dish and then under the microscope. Pour

a little ethanol onto the worm.

Focus using the focusing knob on the side of the microscope. You

may need to move the specimen to view different parts.

Use figure 2 over the page to see if you can find:

� the saddle (clittelum),

� the saddle pad (tubercula pubertatis) and the

� setae (small hairs on each segment that may look like

black spots)

Look carefully at the tip of the head. Compare it with the shapes (a)

–(f) below. Which letter does it look most like?

View from above

View from above

View from side

View from side

Figure 1: Dorsal and lateral views of the tip of the head (prostomium)

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Figure 2. A typical earthworm (lob worm- Lumbricus terrestris).

The roman numerals show the segment numbers. Not all earthworms

look the same. For example you may not be able to see the male or

female pore on the species that you have.

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One person answer questions 1-6 on page 6 of the workbook whilst the

other person digs a hole 20cm x 20cm and 10cm deep (using a spade).

Put the soil from the hole on to a bin liner. Sort carefully through the soil

and remove earthworms gently and put them into a container. Break up any

clumps in the soil. There may be worms inside.

Count any worms you find and decide how many adults and how many

immature worms you have. The immature worms do not have a saddle and

can’t be identified to species level. Record the number of adults and

immature worms in the workbook.

Get a stopwatch. Empty the mustard into a water bottle, replace the lid and

shake to mix thoroughly. Start the stopwatch. Pour the mustard solution

into the pit, time how long it takes to completely drain. If it is less than 3

minutes write the time in your workbook. If it is more than 3 minutes move

on to the next step.

Collect any worms that come up with the mustard and put them into a

separate container. Rinse these worms carefully to get rid of the mustard

water. Don’t mix these worms with the worms from your soil pit.

Count the worms from the mustard water and decide how many adults and

immature worms you have. Write this number in your work book below

where you wrote the time taken for the water to drain.

Test the soil properties by following the instructions on the laminated field

guide (Tasks 7 to 15). Record your results in your workbook.

Identify any adult earthworms you have using the field guide. Ask for help if

you aren’t sure. Don’t forget to measure the length of any adult worms and

write this into the table.

Return any worms to a safe place under some leaves and away from any

mustard. Fill in the hole. Put the grass back on top and stamp down so

there are no traces of you being there.

Make sure all of your observations are recorded in the workbook.

OPAL Soil and Earthworm Survey

26

Further Information and Links

Thank you for coming to the Masterclass! We hope you enjoyed the

day!

For further information on anything you have seen today or details

about studying at the University of Nottingham, please email

scienceoutreachproject@nottingham.ac.uk, or go to the project website at www.nottingham.ac.uk/sop.

For additional information about any of the departments involved in

the Science Outreach Project or today’s event, check out the following webpages:

School of Biology: www.nottingham.ac.uk/biology

School of Biosciences: www.nottingham.ac.uk/biosciences

OPAL: www.opalexplorenature.org