A Story of the Syilx and Secwépemc

Told to Dr. McNeil by UBCO Prof. Emerita Dr. Sandra Peacock

Told to her by Secwépemc elders Dr. Mary Thomas and Lilly Harry

​

Dr. Sandra Peacock

Dr. Mary Thomas

Lilly Harry

A Story of the Syilx and Secwépemc

Balsamroot (Balsamorhiza sagittate) or spring sunflower

• Tall (80 cm) single-stalked yellow flower, large silvery arrow-shaped leaves, thick deep taproot (approx. 4 x 20 cm)
• roots were a traditional dietary staple for Secwépemc and Syilx peoples
• in Secwépemctsín: tséts’elq
• in Nsyilxcən: smúkʷaʔxn

How to prepare balsamroot

• harvest roots, beat to remove outer bark covering
• dig a pit, 80 – 100 cm deep, perhaps 1 – 2 m across
• flat stones in the bottom, pile wood on top, burn it
• place a vertical stick in the centre of the hot stones
• thin layer of earth or the root peelings on stones, �thick layer of Douglas fir branches
• pour water (~ 3 – 4 L) on the branches
• layer peeled roots on the branches
• second layer of fir branches
• cover with earth
• remove the vertical stick, pour water �into channel, fill pit with steam
• pile wood on top, burn it, cook 2 – 3 days

Figures from: Peacock, S. L. Botany 2008 86 116-128

wood

branches

branches

roots

earth

wood

stones

Some questions to consider about balsamroot pitcooking…

1. Why add so much water? Why fill the pit with steam?
2. Why a cooking pit for three days with hot rocks and fire�(and not, e.g. simply roasting on a fire for a few hours)?
3. The principal nutritive content of this food is carbohydrate. �Why are carbohydrates a high-energy food source?
4. Why layer the roots between fresh fir branches?
5. What chemical reaction occurs during this cooking process? What is the mechanism of that reaction?
6. Why does the preparation of balsamroot require such an elaborate, labour-intensive process? Why not eat it raw?

​

A question to consider…

Why add fresh fir branches to the cooking pit?

(suggest a reason in one or two words)

​

menti.com

A Story of the Syilx and Secwépemc

Balsamroot roots were a traditional food for the Secwépemc and Syilx peoples

• in Secwépemctsín: tséts’elq
• in Nsyilxcən: smúkʷaʔxn

Balsamroot preparation

• harvest roots, beat to remove outer bark covering
• dig a pit, 80 – 100 cm deep, perhaps 1 – 2 m across
• flat stones in the bottom, pile wood on top, burn it
• place a vertical stick in the centre of the hot stones
• thin layer of earth or the root peelings on stones, �thick layer of Douglas fir branches
• pour water (~ 3 – 4 L) on the branches
• layer peeled roots on the branches
• second layer of fir branches
• cover with earth
• remove the vertical stick, pour water �into channel, fill pit with steam
• pile wood on top, burn it, cook 2 – 3 days

This process

• is highly complex, labour-intensive
• is carefully engineered and precise
• reveals detailed and sophisticated Indigenous knowledge

What’s the chemical reaction?

Principal nutrient in balsamroot: inulin

• complex carbohydrate
• polymer of fructose sugar molecules
• humans cannot digest it!
• requires a chemical reaction to �break apart the polymer

​

H[C₆H₁₀O₅]_nOH(s) + (n – 1) H₂O(g) 🡺 n C₆H₁₂O₆(s)

inulin + lots of water 🡺 lots of fructose

water is a stoichiometric reactant!

the process needs a lot of water!

What’s the reaction mechanism of inulin hydrolysis?

If we represent inulin as (fructose)_n and an acid catalyst as HA, the mechanism to cleave off one fructose molecule can be described as:

​

What is the expected order in the acid HA?

a) zero order b) first order c) second order

1 HA reacts�before the�slowest step, so �first order in HA!

rate = k[HA]^a[H₂O]^b[inulin]^c

rate = k[HA][H₂O]^b[inulin]^c

What’s the reaction mechanism of inulin hydrolysis?

If we represent inulin as (fructose)_n and an acid catalyst as HA, the mechanism to cleave off one fructose molecule can be described as:

​

Inulin reacts�before the�slowest step, �but it’s a solid! �Its concentration cannot change! �It should be �zero order!

rate = k[HA][H₂O]^b[inulin]^c

rate = �k[HA][H₂O]^b

What is the expected order in inulin, the (fructose)_n ?

a) zero order b) first order c) second order

What’s the reaction mechanism of inulin hydrolysis?

If we represent inulin as (fructose)_n and an acid catalyst as HA, the mechanism to cleave off one fructose molecule can be described as:

​

H₂O reacts�after the�slowest step! �It should be �zero order!

rate = �k[HA][H₂O]^b

rate = �k[HA]

What is the expected order in H₂O?

a) zero order b) first order c) second order

What’s the reaction mechanism of inulin hydrolysis?

If we represent inulin as (fructose)_n and an acid catalyst as HA, the mechanism to cleave off one fructose molecule can be described as:

​

cannot use reactant concentrations to control rate!

can only use temperature!

rate equation:

• zero order in inulin, it’s (s)!
• zero order in H₂O, reacts after slowest step!
• first order in �HA catalyst
• rate = k[HA]� = k’�at constant [HA]

What’s the reaction rate?

Peacock paper: < 30% conversion after 1 day if T_init ~100 °C

• E_a ≈ 120 kJ/mol: very high activation barrier!
• k’(100 °C) ≈ 3.2×10^–4 s^–1, k’(75 °C) ≈ 2.6×10^–5 s^–1�

very high T needed for even �a slow reaction rate!

drop of 25 °C makes reaction > 10x slower!

maintaining high T is critical!

Dr. Sandra�Peacock

Peacock, S. L. �Botany 2008 86 116-128

Some questions to consider about balsamroot pit-cooking…

1. Why add so much water? Why fill the pit with steam?
2. Why a cooking pit for three days �(and not, e.g. simply roasting on a fire for a few hours)?
3. The principal nutritive content of this food is carbohydrate. �Why are carbohydrates a high-energy food source?
4. Why layer the roots between fresh fir branches?
5. What chemical reaction occurs during this cooking process? What is the mechanism of that reaction?
6. Why does the preparation of balsamroot require such an elaborate, labour-intensive process? Why not eat it raw?

​

What does kinetics reveal about this process?

• need lots of H₂O for reaction stoichiometry
• H₂O must permeate solid inulin to react
• But! More H₂O doesn’t increase rate! Zero order in [H₂O]!
• very high E_a, requiring prolonged high T

​

add lots of water!

fill the pit with steam!

hot rocks below, fire above!

must cook for days!

but where does the acid catalyst come from??

Balsamroot preparation

Figures from: Peacock, S. L. Botany 2008 86 116-128

• harvest roots, beat to remove outer bark covering
• dig a pit, 80 – 100 cm deep, perhaps 1 – 2 m across
• flat stones in the bottom, pile wood on top, burn it
• place a vertical stick in the centre of the hot stones
• thin layer of earth or the root peelings on stones, �thick layer of Douglas fir branches
• pour water (~ 3 – 4 L) on the branches
• layer peeled roots on the branches
• second layer of fir branches
• cover with earth
• remove the vertical stick, pour water �into channel, fill pit with steam
• pile wood on top, burn it, cook 2 – 3 days

This process

• is highly complex, labour-intensive
• is carefully engineered and precise
• reveals detailed and sophisticated Indigenous knowledge

What is the enthalpy change of inulin hydrolysis?

inulin hydrolysis is not (very) exothermic!

Δ_rH = Σ(bonds broken) – Σ(bonds formed)

= D(O-H) + D(C-O) – D(O-H) – D(C-O) ≈ 0!

(Different IMFs might result in �Δ_rH of maybe ± 20 kJ/mol, not large effects)

Based on bonds broken and formed, Δ_rH is

a) endothermic

b) about 0

c) exothermic

What is the enthalpy change of inulin hydrolysis?

H₂O(g) has higher enthalpy than H₂O(ℓ)!�inulin hydrolysis with steam is exothermic!

But! H₂O(g) 🡺 H₂O(ℓ) ∆H = –∆_vapH = –44 kJmol^–1

H[C₆H₁₀O₅]_nOH + H₂O(ℓ) 🡺 H[C₆H₁₀O₅]_n–1OH + C₆H₁₂O₆ ∆H ≈ 0

H[C₆H₁₀O₅]_nOH + H₂O(g) 🡺 H[C₆H₁₀O₅]_n–1OH + C₆H₁₂O₆ ∆H = –44 kJmol^–1

If H₂O(g) is used to hydrolyze inulin instead of H₂O(ℓ), the reaction is

a) endothermic

b) still ∆H ≈ 0

c) exothermic

inulin

fructose

What do you use fructose for?

combustion of fructose: C₆H₁₂O₆ + 6 O₂ 🡺 6 CO₂ + 6 H₂O ΔH_total

glycolysis: C₆H₁₂O₆ 🡺 2 AcCO₂H + 4 H⁺ + 4e^– ΔH₁

pyruvate oxidation: 2 AcCO₂H + 2 HSCoA 🡺 2 AcCoA + 2 CO₂ + 4 H⁺ + 4 e^– ΔH₂

citric acid cycle: 6 H₂O + 2 AcCoA 🡺 2 HSCoA + 4 CO₂ + 16 H⁺ + 16e^– ΔH₃

mitochondrial et chain: 24 H⁺ + 24e^– + 6 O₂ 🡺 12 H₂O ΔH₄

What’s the biological role of fructose (or any sugar) when you eat it?

1. to build proteins & enzymes!
2. to synthesize fats!
3. as an energy source!
4. to make DNA and RNA!

amino acids 🡺 proteins

fatty acids + glycerol 🡺 lipids

sugars 🡺 carbohydrates

nucleotides 🡺 nucleic acids

6

What do you use fructose for?

O₂ has very weak bonds, so fructose combustion is highly exothermic�Δ_rH = –2810 kJmol^–1

fructose

C₆H₁₂O₆ + 6 O₂ 🡺 6 CO₂ + 6 H₂O

Some questions to consider about balsamroot pit-cooking…

1. Why add so much water? Why fill the pit with steam?
2. Why a cooking pit for three days �(and not, e.g. simply roasting on a fire for a few hours)?
3. The principal nutritive content of this food is carbohydrate. �Why are carbohydrates a high-energy food source?
4. Why layer the roots between fresh fir branches?
5. What chemical reaction occurs during this cooking process? What is the mechanism of that reaction?
6. Why does the preparation of balsamroot require such an elaborate, labour-intensive process? Why not eat it raw?

​

What does thermodynamics reveal about this process?

• H₂O(g) is much higher-energy than H₂O(ℓ),�hydrolysis with H₂O(g) is more favourable!
• combustion of carbohydrates is highly exothermic, O₂ has weak bonds

​

fill the pit with steam!

fructose (like all sugars) is a high-energy food source!

Balsamroot preparation

• harvest roots, beat to remove outer bark covering
• dig a pit, 80 – 100 cm deep, perhaps 1 – 2 m across
• flat stones in the bottom, pile wood on top, burn it
• place a vertical stick in the centre of the hot stones
• thin layer of earth or the root peelings on stones, �thick layer of Douglas fir branches
• pour water (~ 3 – 4 L) on the branches
• layer peeled roots on the branches
• second layer of fir branches
• cover with earth
• remove the vertical stick, pour water �into channel, fill pit with steam
• pile wood on top, burn it, cook 2 – 3 days

Figures from: Peacock, S. L. Botany 2008 86 116-128

This process

• is highly complex, labour-intensive
• is carefully engineered and precise
• reveals detailed and sophisticated Indigenous knowledge

What’s the reaction mechanism of inulin hydrolysis?

If we represent inulin as (fructose)_n and an acid catalyst as HA, the mechanism to cleave off one fructose molecule can be described as:

​

rate equation:

• zero order in inulin, it’s (s)!
• zero order in H₂O, reacts after slowest step!
• first order in �HA catalyst

rate = k[HA] = k’ at constant [HA]

reaction only proceeds if an acid catalyst is present!

Where does the acid come from? What’s the acid?

steam distillation of Douglas fir essential oils: lots of shikimic acid!

Why is shikimic acid (weakly) acidic?

resonance in the conjugate base�–CO₂^– group makes –CO₂H acidic! Shikimic acid has a low pK_a value!

The pK_a of shikimic acid is 4.15. �Which H atom most easily dissociates as H⁺?�a) one of the C-H H atoms (not shown explicitly)

b) the blue one

c) the orange one

d) one of the red ones

Some questions to consider about balsamroot pit-cooking…

1. Why add so much water? Why fill the pit with steam?
2. Why a cooking pit for three days �(and not, e.g. simply roasting on a fire for a few hours)?
3. The principal nutritive content of this food is carbohydrate. �Why are carbohydrates a high-energy food source?
4. Why layer the roots between fresh fir branches?
5. What chemical reaction occurs during this cooking process? What is the mechanism of that reaction?
6. Why does the preparation of balsamroot require such an elaborate, labour-intensive process? Why not eat it raw?

​

What does acid-base chemistry reveal about this process?

• the reaction requires an acid catalyst
• steam distillation of fir needles �extracts large amounts of shikimic acid
• resonance in the –CO₂^– of shikimate�makes the –CO₂H group acidic!

​

fill the pit with steam, extract acid from fir needles!

place roots between �layers of fresh fir branches to supply the acid catalyst!

What are the fir branches for?

shikimic acid catalyst!

Balsamroot preparation

• harvest roots, beat to remove outer bark covering
• dig a pit, 80 – 100 cm deep, perhaps 1 – 2 m across
• flat stones in the bottom, pile wood on top, burn it
• place a vertical stick in the centre of the hot stones
• thin layer of earth or the root peelings on stones, �thick layer of Douglas fir branches
• pour water (~ 3 – 4 L) on the branches
• layer peeled roots on the branches
• second layer of fir branches
• cover with earth
• remove the vertical stick, pour water �into channel, fill pit with steam
• pile wood on top, burn it, cook 2 – 3 days

Figures from: Peacock, S. L. Botany 2008 86 116-128

This process

• is highly complex, labour-intensive
• is carefully engineered and precise
• reveals detailed and sophisticated Indigenous knowledge

What’s the reaction mechanism of inulin hydrolysis?

steps 2 and 3: a nucleophilic substitution reaction! replaces H[C₆H₁₀O₅]_nOH with H₂O!

In this nucleophilic substitution reaction, what’s the nucleophile?

a) the inulin polymer chain

b) shikimic acid c) H₂O d) C₆H₁₁O₅⁺

The nucleophile forms a new bond with the electrophilic atom in the electrophile.

What’s the reaction mechanism of inulin hydrolysis?

steps 2 and 3: a nucleophilic substitution reaction!

In this nucleophilic substitution reaction, what’s the leaving group?

a) the inulin polymer chain

b) shikimic acid c) H₂O d) C₆H₁₁O₅⁺

The leaving group breaks a bond from the electrophilic atom in the electrophile.

What’s the reaction mechanism of inulin hydrolysis?

steps 2 and 3: a nucleophilic substitution reaction!

Is this nucleophilic substitution reaction S_N1 or S_N2?

a) S_N1 b) S_N2 c) both d) neither

S_N1 has two steps: LG leaves, an intermediate forms, then Nu attacks

Why do we need an acid catalyst for inulin hydrolysis?

steps 2 and 3: a nucleophilic substitution reaction!

Why do we need an acid catalyst?

1. It makes the Nu more nucleophilic
2. It makes the LG a better LG
3. It makes the products more stable

RO^– is a poor LG, but ROH is a great LG! Loss of LG is the rate-determining step!

Why is inulin hydrolysis so slow?

Why does the slow step have such a high energy barrier?

1. it involves breaking a bond
2. the entropy change is unfavoured
3. H₂O is a poor nucleophile

②

The rds in S_N1 is always loss of LG, because breaking a bond is always uphill!

Some questions to consider about balsamroot pit-cooking…

1. Why add so much water? Why fill the pit with steam?
2. Why a cooking pit for three days �(and not, e.g. simply roasting on a fire for a few hours)?
3. The principal nutritive content of this food is carbohydrate. �Why are carbohydrates a high-energy food source?
4. Why layer the roots between fresh fir branches?
5. What chemical reaction occurs during this cooking process? What is the mechanism of that reaction?
6. Why does the preparation of balsamroot require such an elaborate, labour-intensive process? Why not eat it raw?

​

What does organic chemistry reveal about this process?

• inulin hydrolysis is an S_N1 reaction, substituting H₂O for inulin polymer to generate fructose
• rds of the reaction must break a bond from �the LG: high energy barrier, requires good LG
• acid changes poor LG RO^– into good LG ROH

fir branches supply the acid catalyst!

reaction requires �high temperature, �long reaction times, �and acid catalyst

rds: break this bond!

A Story of the Syilx and Secwépemc

Told to Dr. McNeil by UBCO Prof. Emerita Dr. Sandra Peacock

Told to her by Secwépemc elders Dr. Mary Thomas and Lilly Harry

​

Dr. Sandra Peacock

Dr. Mary Thomas

Lilly Harry

Peacock, S. L. Botany 2008 86 116-128

Read more about regional Indigenous plant uses!

Secwepemc people and plants: research papers in Shuswap ethnobotany; Ignace, M. B., Turner, N. J., Peacock, S. L., Eds.; Society of Ethnobotany, 2016. Available via the UBC library or as a free pdf at ethnobotany.org

Dr. Sandra Peacock