Unit 3 - Agave

Question 1

What is the aim of processing agave?

Answer 1

To extract the fermentable sugars in the agave pina.

Question 2

What are the four steps to processing agave pinas?

Answer 2

Cutting - cut into halves or quarters
Cooking -Cooked in ovens
Milling - cooked pieces of agave are milled to extract the agave juice
Mixo tequila additions - in some distilleries, other sources of sugar are added to the agave juice before fermentation

Question 3

What does cutting the pinas achieve?

Answer 3

It makes processing faster and more effective. It’s also easier to handle

Question 4

Describe what happens inside when the pinas are cooked

Answer 4

inulin is converted to fermentable fructose sugar

Question 5

Describe inulin

Answer 5

Inulin is made from chains of fructose molecules linked together. There can be between 2 and 20 fructose molecules in a chain of inulin

Question 6

How do we break down inulin into fructose for fermentation?

Answer 6

Using heat.

Heat increases the rate reaction that breaks down the B-(2,1) bonds ( a bond between carbon 1 of one fructose and carbon 2 of a second fructose) between fructose molecules in inulin.

Question 7

Which spirit uses the traditional cooking method of cooking pits

Answer 7

Traditionally, agave pinas are cooked in a pit dug into the ground lined with stones. This method of cooking is used to make mezcal and rarely in tequila

Question 8

Describe cooking pits

Answer 8

at least 3m in diameter and lined with rocks
Wood (normally oak or pine) is stacked in the centre of the pit.
Rocks are laid around the wood, leaving a opening at the top.
The wood is set on fire through the opening, using hot coals & the fire is left to burn for a few hours heating up the rocks surrounding the burning wood

A layer of straw or agave fibres is placed on top of the rocks. The pinas are placed on top of the fibres and covered with soil or hay

Question 9

How long are pinas left in the cooking pit to cook?

Answer 9

7 days. During this time, the inulin breaks down into fructose and the pinas take on a smoky aroma from the wood fire.

Question 10

Describe cooking hornos

Answer 10

an oven - used in small and large distilleries
Usually made of brick, clay or ceramics.
Some are capable of holding over 40t of pinas
The hornos are heated by steam injection through either the top or the bottom of the oven

Question 11

How long do we cook pinas in the hornos?

Answer 11

to a temp of 100C for between 36-48hrs

During this, the inulin breaks down into fermentable fructose. The cooking process also removes bitter waxes and dirt from the pinas which drip down through a perforated floor of the hornos

After cooking temp has been reached, the steam injection is stopped and the pinas stay n the oven for an additional 24-48hr.

Question 12

What is an autoclave?

Answer 12

a type of pressure cooker that is typically used in large industrial tequila distilleries . They are generally steel vessels with an opening at one end. The pinas are loaded into the autoclave and the door sealed. An autoclave heats up the pinas like a hornos but also uses pressure to speed up the cooking process.

Question 13

Describe how autoclaves work

Answer 13

Steam is used to inject the temperature of the pinas and wash any bitter waxes and dirt the pinas. Just like the hornos this falls through the perforated floor.

Steam is continuously added until the autoclave reaches a pressure of 1.2kg/cm2 (118pka) and a temp of 121c.

The steam injection is then stopped and the pinas continue to cook under pressure.

Question 14

How long does cooking pinas in an autoclave take?

Answer 14

8-16hrs which is quicker than a cooking pit or hornos

Question 15

What is a diffuser?

Answer 15

a machine that is designed to recover the maximum amount of sugar from the agave material.

Question 16

Can the agave plants go straight into the diffuser?

Answer 16

No, they plant material must be broken down before it enters the diffuser. To do this, the pinas are fed through a processing line, where they are first chopped into small pieces and then shredded to expose all the fibrous materials.

Question 17

What is the process of the diffuser?

Answer 17

The shredded material is fed to the diffuser where the pina fibres are sprayed with hot water and steam as they pass through. This rinses the fructans from the agave pulp

Juice produced is transferred into large autoclaves where it is heated and pressurised again. Sulphuric acid can then be added to the juice which catalyses the breakdown of inulin into simple fructose.

Question 18

What are advantages of diffusers?

Answer 18

Diffusers are used in this process solely to increase sugar extraction, rather than to lower processing times.

Using a diffuser also means that the cooked piñas do not need to be milled.

Question 19

How is agave traditionally milled?

Answer 19

using a tahona which is a circular stone weighting more than 1.5t.

As the stone rotates it crushes the agave into a pulp containing plant fibres and juice. In tequila production, the plant fibres are normally separated from the juice and then the juice is pumped into a fermenter.

In mezcal production, the plant fibres and juice are fermented together

Question 20

Describe modern agave mills

Answer 20

These machines use a series of wheels or paddles to shred the cooked piñas and allow the juice to drain out and be pumped away.
To increase efficiency, the plant fibres are often crushed multiple times. They are then rinsed with hot water to make sure as much of the fermentable sugars have been removed as possible.
This method of milling is significantly more efficient than traditional tahonas. If these mills are operated efficiently, they can extract up to 85% of the available sugars from the piñas

Question 21

What is bagazo and what can they be used for?

Answer 21

the plant fibres from agave & They may be used for fuel, turned into fertiliser, or even as furniture stuffing

Question 22

How much Mixto tequila additions did the Consejo Regulador del Tequila (CRT) regulations say can be added to tequila?

Answer 22

49% of other fermentable materials in addition to agave

Question 23

What are the additional materials that can be added for mixto tequila?

Answer 23

These fermentable materials may be high grade molasses, sucrose, glucose, or corn syrup.

Additional sugars are typically added during, or just after, the milling process. This allows the distiller to ensure a consistent sugar level at the start of fermentation. We will discuss fermentation in the next unit.

Question 24

What happens with the plant fibres (bagazo) after milling in tequila production vs mezcal?

Answer 24

Tequila - plant fibres are usually separated from the juice then sent to the fermenter

Mezcal plant fibres and juice are fermented together