Tetley Ale malt specifications (part three)

This going really well. This is my third post based on Tetley's specification manuals. And I haven't even got off the first page yet.

Lots of technical stuff today, that I don't fully understand. Let's be honest, that I don't understand at all. So excuse me if I make lots of stupid mistakes.

I've repeated the table again at the bottom so you have something to refer to on this page. 

The next nitrogen figure now. SNR, Soluble Nitrogen Ratio. I'll let the real scienticians explain it.

2.3.3. Soluble Nitrogen Ratio (Kolbach Index)
Soluble nitrogen ratio of the malts was based on the concentration of soluble protein present in the malt and concentration of total protein in the malt and calculated according to the formula below:

SNR = S/T * 100%

S — concentration of the soluble protein in the malt (% w/w, dry mass)
T — concentration of total protein in the malt (% w/w, dry mass)

Błazewicz, J.; Kawa-Rygielska, J.; Leszczynska, D.; Grabinski, J.; Gasinski, A. Influence of Variety and Nitrogen Fertilization on the Technological Parameters of Special Malts Prepared from Naked and Hulled Oat Varieties. Agronomy 2021, 11, 2566. https://doi.org/10.3390/agronomy11122566, pages 5 - 6.

The next bit explains what the significance of the SNR is:

Proteins present in the malt are broken down by proteolytic enzymes during the mashing process to forms, such as, for example, free amino acids, that can be used by yeast; therefore, the use of raw material that is too low in protein may adversely affect the fermentation process of the wort. In addition, too low protein content in the wort may contribute to the deterioration of the stability and quality of the foam of the produced beer. Excessive content of protein enzymatic hydrolysis products, especially high-molecular ones, deteriorates the clarity of beer and facilitates the formation of various types of turbidity.
Błazewicz, J.; Kawa-Rygielska, J.; Leszczynska, D.; Grabinski, J.; Gasinski, A. Influence of Variety and Nitrogen Fertilization on the Technological Parameters of Special Malts Prepared from Naked and Hulled Oat Varieties. Agronomy 2021, 11, 2566. https://doi.org/10.3390/agronomy11122566, page 10.

Is that clear? Too little, and there might be problems with the fermentation and head retention. Too much, and your beer would be cloudy. It makes sense that you'd want to have the right level.

How much was too much and how much was too little? I'll leave the explanation to the scientists again:

The parameter that describes the ratio of the soluble protein content to the total protein content is the Kolbach index, which indicates the percentage of proteins that have undergone enzymatic hydrolysis during the malting and mashing process and may be dissolved in the wort. Too low Kolbach index usually indicates insufficient activity of proteolytic enzymes present in the produced malt. The brewing technology usually uses malts with Kolbach index above 35% and below 45%. Malt with a Kolbach number above 41% is described in malting terminology as having “very good proteolytic relaxation” and is well seen in the brewing industry.
Błazewicz, J.; Kawa-Rygielska, J.; Leszczynska, D.; Grabinski, J.; Gasinski, A. Influence of Variety and Nitrogen Fertilization on the Technological Parameters of Special Malts Prepared from Naked and Hulled Oat Varieties. Agronomy 2021, 11, 2566. https://doi.org/10.3390/agronomy11122566, page 10.

I'm really glad that they give specific values. 35% to 45% was what you were looking for. Which means that the Leeds and Romford malts were right at the bottom end of good., While Castlemaine 4X was up towards the top end. That's quite a large variation. I suppose that there must have been some point to it.

I think that's about enough for today. Still lots more to come. Probably more entertaining when I get onto the beers. Don't worry. They'll be along soon.

Tetley Ale malt specifications
1.1 Extract	282 brl°/336 lb (on dry)
	301 l°/kg (on dry)
1.2 Fine coarse difference	2-7 brl°/226 lb.
1.3 Moisture	not more than 3.5%
1.4 Colour	5.5 ± 1.5° EBC
	6.5 ± 1.5° EBC (Leeds)
	4.5 ± 1.5° EBC (Castlemaine 4X)
1.5 Total N	1.60 ± 0.1% average
	not more than 1.90% on individual samples
1.6 TSN (total soluble nitrogen)	0.60 ± 0.04% (Burton, Warrington)
	0.58 ± 0.04% (Leeds, Romford) -
	not more than 0.70% on individual samples.
	0.65 ± 0.5% (Castlemaine 4X)
1.7 SNR (specific nitrification rate)	38 ± 2 (Burton, Warrington)
	36 ± 2 (Leeds, Romford)
	41 ± 2 (Castlemaine 4X)
1.8 FAN (free amino nitrogen)	180 ± 20mg/1 at 1048 0G
	200 ± 20mg/1 at 1048 0G (Castlemaine 4X)
	150 ± 20mg/1 at 1048 OG (Leeds)
1.9 Arsenic	not more than 0.5 mg/kg.
1.10 Lead	not more than 1.0 mg/kg.
1.11 Dust and Offal	not more than 2.0% (2.2 mm screen)
1.12 NDMA (N-Nitroso-dimethylamine)	not more than 5 μg/k
Source:
Tetley Beer and Malt Specifications, 1985, malt page 1.