Maceration in Cider

Image source: https://www.tompress.it/A-10004096-sidro-lasciare-macerare-o-fermentare-le-mele.aspx

We can define maceration as the controlled contact between a solid matrix (pulp) and a liquid (must) to extract or transform the latter for technological-organoleptic purposes.

In this process, the main factors to control in the winery are:

1. Contact with oxygen (oxidative vs reductive process),
2. Temperature,
3. Time.

While the main factors to control during harvest/storage are:

1. Mixture of varieties,
2. Technological maturity point (pH, concentration of total phenols, pectins, and enzymes).

This way, through maceration, we can profoundly change the cider profile:

• Greater yield in pressing and greater clarity in cider: By action of PME (polygalacturonase) and PG (polymethyl-esterase) enzymes.
• Extraction of aromas from aromatic precursors in apple skin, by action of the enzyme beta-glucosidase.
• Formation of desired aromatic compounds (such as 2-phenylethanol and 1,3-octanediol), greater color (or lesser depending on the process), and reduction of bitterness and astringency (mainly), by action of the polyphenol oxidase enzyme acting in the oxidation reaction system of phenolic compounds.
• Development of microorganisms: Mainly through temperature control. For example: traditional English-French ciders at low temperature (10ºC), traditional Spanish ciders at higher temperatures.

Let’s start with the basics… since it is quite a complex process to understand and has not yet been fully clarified in cider, let’s specifically talk about the effect of oxidative maceration.

Lea, A. G. (1992). Flavor, color, and stability in fruit products: The effect of polyphenols. In Plant polyphenols (pp. 827-847). Springer, Boston, MA.

Oxidative Maceration of Must

As Dr. Andrew Lea stated in the TCCPA CraftCon 2020 talk, who worked for 13 years at the legendary Long Ashton Research Station (an English institute that dealt with apples and cider), an interesting phenomenon occurs when performing oxidative maceration of must with pulp for a certain time.

If we took samples during maceration, pressed and analyzed the must, we would observe the following:

1. Initially, the must color would increase (browning) due to the formation by oxidation of colored phenolic compounds (quinones), starting from colorless phenolic compounds (procyanidins) in a complex and regenerative reaction involving the polyphenol oxidase enzyme.
2. Meanwhile, the total phenol level starts to decrease, mainly because they would “tan” inside the pulp, acting as “consumers” of these colored phenolic compounds.
3. Eventually, the “Tanning” process would surpass the formation of colored compounds, “consuming” them in the pulp and finally reducing the color of the subsequent pressings.
4. At the end of the process (many hours), the pulp would be brown, but the pressed must almost colorless.

The ideal point, for traditional French and English ciders (high phenol content apples), would be the point of maximum color formation with significant procyanidin (tannin) removal.

Although this produces a cider of darker color (more orange/brown and less yellow/green), it is still a desired color in these styles, with the advantage of lower turbidity due to the removal of unstable procyanidins and enzymatic action on pectins, higher aromatic quality due to the formation of aromatic compounds by oxidation and release of others by enzymatic action.

In this process, we should add the shape of the maceration tank as a factor, in addition to those already mentioned.

However, we should not be afraid of the must color at the time of maceration and pressing (quite dark), as after fermentation, the color decreases by 50%, but the total phenol content does not.

Therefore, a golden/orange, clean, aromatic, and less astringent cider is obtained.

Lea, A. G. (1992). Flavor, color, and stability in fruit products: The effect of polyphenols. In Plant polyphenols (pp. 827-847). Springer, Boston, MA.

Pressed must of Renetta and Rossa Romana apples produced by: oxidative maceration (left) vs. direct pressing (right, without maceration). The former had aromas of ripe apple, dried flowers and earth; the latter has a profile of white flowers, citrus and herbs.

Maceration and Sulfur Dioxide

As final points, I would say that in this case, we are only talking about oxidative maceration and, as I mentioned, the process depends on many factors that each producer must ultimately perfect.

However, 2 to 6 hours of maceration (maximum 12) and an ideal temperature of 4-5ºC (maximum 10ºC) during this process should work well.

Finally, a word on the use of sulfur dioxide in this particular case (oxidative maceration): certainly, diverting the oxidation reaction chain (Fenton reaction), the phenomenon described earlier does not occur if added during maceration (which is uncommon), especially in high doses..

Therefore, it is not recommended to use in high doses, as it could also affect the process following maceration (Keeving) in traditional English-French ciders, due to its inhibitory effect on some yeasts.

We will discuss the effect of maceration on the natural clarification of must known as “Keeving” in another article.

Cin cin!

Cristian Galaz Torres,
Ing. Agronomo-Enologo.
PhD(c) Università di Bologna.
Consulente sidro.

@cristiangalazt

Bibliografia

Pereda Rodriguez, M. A. (2011). Elaboración de sidra natural ecológica. Mundi-Prensa Libros.

Lea, A. G. (1992). Flavor, color, and stability in fruit products: The effect of polyphenols. In Plant polyphenols (pp. 827-847). Springer, Boston, MA.

TCCPA CraftCon live! Fenolici con il Dr. Andrew Lea, 2020. https://youtu.be/OezB-pubhZ4