Category Archives: Flavour modification

Diacetyl Control: Using ALDC to brew the beer you intended

What is ALDC? Alpha acetolactate decarboxylase.

Benefits of ALDC:

·        Reduces Diacetyl production
·        Significantly reduces maturation times
·        More efficient vessel utilisation
·        Improves beer quality

Diacetyl is well known among brewers and beer drinkers – distinctive for its buttery aroma and flavour. It is both produced and removed naturally by ale and lager yeast strains alike during the course of a typical fermentation and many reliable house yeasts leave a little residual diacetyl in the finished beer. As such it is fairly common with many traditional and popular beer styles to contain some level of diacetyl in their flavour profile.

Murphy and Son has worked with a number of craft breweries in the USA and United Kingdom who wanted to produce modern, hoppy pale ales without any flavour of diacetyl, but that was brewed using their existing house ale strain of yeast. The concentration of diacetyl was initially monitored to see how it was being lowered by the breweries controlled fermentation and how effective the yeasts own ability to reabsorb and reduce the diacetyl during maturation was.

Murphy and Son analysed this beer for diacetyl levels in their laboratory in Nottingham, England. It was found that by applying ALDC to the wort at the same time as the yeast was added in a concentration of 3 to 4 grams per hectolitre, the flavour would be brought below threshold in the finished beer as desired (figure 1).

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ALDC is commonly used in lager production to lower maturation time, the rate-limiting step, by converting acetolactate (the precursor of diacetyl) to a flavourless end-product called acetoin. (figure 2 below).

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In this instance the ALDC was able to boost the diacetyl lowering effect of the yeast in the same way, culminating in the desired low concentrations of diacetyl in the finished beer and allowing the brewer to broaden the spectrum of beers produced without the need for another yeast.

As ale fermentations are much faster a little more ALDC was required than may be needed for lager, but at 3 to 4 grams per hectolitre of ALDC it was still found to be an economical solution to the brewer.

Murphy and Son Ltd sell ALDC in 1kg pack sizes!

ZETOLITE – Flavour modification Reduces H2S and DMS off flavours

ZETOLITE – Flavour modification Reduces H2S and DMS off flavours

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Beer Flavour modification.

It is well known in the brewing world that zinc and copper are required by yeast in trace amounts for cell growth, respiration and reproduction. They enjoy better viability and vitality when these compounds are present in the nutritional mix presented to the yeast.

Murphy & Son Ltd in conjunction with the Zetol Cooperation have developed a product called Zetolite that can be added to wort at the start of fermentation or to beer at the start of maturation to assist in the healthy growth of yeast and in particular to either prevent or reduce the incidence of sulphidic compounds such as hydrogen sulphide or dimethyl sulphide.

Zetolite consists of an aluminosilicate carrier, commonly called zeolite, which is impregnated with either zinc or copper ions. It is a pale pink/red or dark grey powder and is dosed at low levels. There are two types of Zetolite, 63 and 65 being copper and zinc respectively.

Zetolite 65, the zinc-based product, is dosed to wort prior to fermentation at a rate of 0.25 – 1.0g/hl. It prevents the formation of these sulphidic and sulphitic off-flavours/aromas.

Zetolite 63 is the copper-based product and is dosed to beer at the end of fermentation or at the start of cold maturation. Dosage rates are typically 2.0 – 3.0g/hl. It may be so that sulphur-based off-aromas have been detected in the cold beer but with low temperatures, the brewer cannot wait the time necessary to naturally remove the unwanted volatiles. By dosing Zetolite 63 into the cold beer, the residual yeast is stimulated in the presence of the copper to metabolise the sulphur off-flavours quickly away.

Murphy and Son sell this product in 250g, 10kg or 20kg packs.

For more information regarding Zetolites please do not hesitate to contact frances.maud@murphyandson.co.uk

Ascorbic Acid – effective anti-oxidant, increases shelf life and prevents paper off flavours

ASCORBIC ACID E300 – STABILISER is supplied as a fine white to off –white powder.

Perfect pint

Ascorbic Acid can help make a perfect pint

BENEFITS

  • Is an economically effective anti-oxidant
  • Reduces the susceptibility of beer to oxidation haze
  • Increases the shelf-life of pasteurised and non pasteurised beers
  • Prevents “papery” (oxidation) off flavours in the final product

Application:
Solutions of ASCORBIC ACID should always be freshly prepared and treated into the bulk of the beer without delay, if possible metering into the flow of beer to tank. Anti-oxidant treatment is more efficient when added before the beer has had contact with air, i.e. as soon as practica-ble after fermentation. Addition of the material prior to cold storage is common practice, in which case the anti-oxidant should be added when the tank is almost full to minimise contact with air.

Murphy’s sell this product in 25kg

Lactose – Sweetener ideal for stout making

Description

  • Provides a milky, creamy, vanilla-like flavour and a soft mouth feel to the beer
  • Suitable for making stouts and dark beers
  • Doesn’t effect the colour of the Beer

Principles

LACTOSE is an off-white solid sugar or syrup that adds no colour to beers. It is also unfermentable by most brewing yeasts and is added by traditionalist trying to emulate milk stouts. Most brewing yeasts are unable to ferment lactose so when added as a priming sugar, it can only contribute this sweetness.

Application and Rates of use

LACTOSE  is used as a priming sugar and the dosage rates are in the range of  1 to 2 kg per hectolitre of finished beer. The rates can be found by dosing small amounts and tasting the beer, stopping when the desired profile is reached.

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Sulphidic Off Flavours?

ZETOLITE – Sulphidic Off Flavours?                        

Then our Zetolite range is the answer.
Zetolites are concentrated powder products from natural occurring volcanic minerals that can be used as processing aids (not additives) which don’t need to be declared on your product labels. Zetolite 63 contains copper salts formulated to reduce sulphidic off-flavours. The product should be slurried with a small amount of water or product and added to the fermenter or conditioning tank or tank.Zetolite 65 contains zinc salts formulated to prevent sulphidic off-flavours. The product should be slurried with a small amount of water or wort and added to the kettle or fermenter at the start of fermentation.Dosage rates for both products are between 0.25 – 1 gram per hectolitre of wort / beer.Here’s a Testimony, brewer wishes to remain anonymous.

‘I have found Zetolite to be a fast and effective way of removing H2S from beer. It is a useful stock item to have as a back up when the usual process controls adopted to regulate H2S levels have not been successful.’ .