Implementation of ISA S88 batch control standards on a traditional microbrewery system.
Dlodlo, Snqobizizwe Buphilo.
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Beer production dates back to the Babylonian and Monks age in 1000 BC and had no standard manufacturing protocols for a very long time. It was the passing of the purity law by the Germans in 1514 that advanced beer production and handling into a more industrial approach. In the years that followed, beer production has evolved into a very technical and delicate procedure that has high quality control measures. This investigation set out to prove the hypothesis that the implementation of the ISA S88 batch control standards in a traditional microbrewery system would increase process efficiency, as well as product consistency and stability. The study commenced with modifications to an existing traditional microbrewery system that included additional stirring flaps in the mash tun, construction of a wort/water recirculation pipeline coupled with a sprinkler in the lauter tun, and additional heating belts and temperature probes as well as a removable cooling coil in the kettle. Thereafter, an experimental plan was developed to brew Premium English pale ale under consistent conditions defined by the proposed ISA S88 model where quality defining parameters included specific gravity, pH and total dissolved solids, colour, batch volumes, reducing sugars content, free amino nitrogen content, simple sugars and flavour compound concentrations. Six identical batches were brewed and apportioned for fermentation at 14, 16, and 18 °C, respectively. Racking of all fermented batches was performed at 0 °C for two weeks before bottling, conditioning and final storage of all batches of beer at 0, 4, and 18 °C, respectively. A HACH HQ 40d multimeter probe was used for all physico chemical measurements with its various probes whilst a Shimadzu UV – 1800 spectrophotometer coupled with a Shimadzu CPS temperature controller was used for all colourimetric and optical density measurements. Simple sugars and beer flavour compound concentrations were measured by means of an Agilent 7890 A gas chromatography system coupled with an Agilent GC 80 sampler and an inert mass spectrophotometry detector. In the mashing process, the final gravity of the wort was observed to be 14.06 ± 0.18 °P, reducing sugars were found to be 89.47 ± 2.39 g/l. In the lautering stage, the three runnings resulted in 7.92 ± 0.51 °P, 3.95 ± 0.60 °P and 1.67 ± 0.15 °P gravities, corresponding to 7.67 ± 0.55 l, 7.58 ± 0.48 l and 5.45 ± 0.42 l volumes, respectively. The collective volume was 35.71 ± 0.51 l and 167.61 ± 1.71 g reducing sugars were recovered from the spent grain. In the kettle, gravity increased to 12.10 ± 0.46 °P. Upon addition of 462 ± 68.87 g maltose syrup and boiling, the final reducing sugars amount was found to be 1632.97 ± 12.64 g in 26.45 ± 1.34 l of wort. Optimum fermentation and beer storage conditions were noted to be 16 °C and 0 °C, respectively. Flavour compounds formed during this fermentation period were found to be at concentration levels of 4.52 ± 0.24 % v/v, 119.05 ± 9.66 mg/l, and 64.02 ± 7.72 mg/l for ethanol, total fusel alcohols and total esters, respectively. Beer fermented at 16 °C depleted the total simple sugars from 12.99 ± 1.25 g/l to 5.23 ± 0.24 g/l, 10.61 ± 1.61 g/l to 5.24 ± 0.29 g/l, and 8.56 ± 3.12 g/l to 4.84 ± 0.47 g/l for storage temperatures of 0 °C, 4 °C, and 18 °C, respectively. The ethanol concentrations increased during the storage period from 4.57 ± 0.39 % v/v to 5.12 ± 0.43 % v/v, 4.70 ± 0.37 % v/v to 5.24 ± 0.29 % v/v, and 4.82 ± 0.43 % v/v to 5.39 ± 0.22 % v/v for beer stored at 0 °C, 4 °C, and 18 °C, respectively. The primary fermentation temperature of 16 ºC was found to be the most ideal (r² = 0.9551), as it produced a very steady and predictable fermentation trend. There were no pH changes in the beer fermented at 16 ºC, implying that no mouth feel changes in the product‟s taste were significantly possible. The physical and chemical property trends, statistical analyses, and literature comparison of the produced wort and beer proved that ISA S88 batch controlling standards, even in a basic traditional microbrewery, can improve process-product quality and guarantee product quality consistency.