Chapter 7 1000 L IPA Beer Pilot Brewing Experiment

7.1 Method of the 1000 L IPA Beer Pilot Brewing Experiment

By integrating the experimental results above, a complete process route for IPA beer production can be obtained. The specific 1000 L IPA pilot brewing scheme is as follows: according to the experimental methods determined in this thesis, perform barley and wheat steeping and germination processes; after germination is complete, dry the malt; crush the malt using a humidified milling method for charging. Maintain temperature at 56℃, add 112.5 kg barley malt and 37.5 kg wheat malt into 600 L treated water (conclusion obtained by mashing calculation) and hold for 30 min; raise temperature to 65℃ for 1 h; raise to 72℃ for 10 min; raise to 78℃ to terminate mashing. Choose a water temperature range of 78–82℃ for 120 min sparging. Boiling time is 70 min: 10 min after boiling starts, add 25% of total hop input as bittering hops; at 40 min after boiling starts, add 50% of total hop input as bittering hops; the last hop addition is at 60 min of boiling, adding 25% of total hop input as aroma hops. Conduct whirlpool clarification at 85℃ for 30 min, then cool the wort and pump into the fermentation tank. Add 25 L yeast culture into the fermenter. At 20℃, add 120 g/HL–180 g/HL Gansu No.1 aroma hop pellets into a 1000 L fermenter. Carry out main fermentation at 20℃. When gravity drops to 4°P, stop main fermentation and proceed to post-fermentation.

7.2 Testing of Various Indicators of 1000 L IPA Beer

7.2.1 Comparison of Basic Indicators Between IPA Beer and Regular Beer

According to the above operations, brew IPA beer. For six tanks of IPA beer, test the original wort gravity, alcohol content, color, bitterness, α-acids, iso-α-acids, total acid, and total polyphenols using methods specified in GB4927-2008, and compare them with commercially available light-refreshing beer. The results are shown in the following table:

Table 3.0 Comparison of Basic Indicators Between IPA Beer and Light-Refreshing Beer

Test item	Lagering-stage beer indicators	IPA Beer						Light-refreshing beer
		1#	2#	3#	4#	5#	6#
Original wort gravity / °P		13.2	12.6	13.8	13.5	12.3	13.0	10
Alcohol content / %		5.2	5.4	5.5	5.9	4.9	5.4	4.0
Color / EBC		7.0	8.2	7.9	6.5	8.6	7.5	5.3
Bitterness / BU		28.2	30.6	29.6	32.4	27.8	31.2	8.5
α-acids / (mg/L)		0.69	0.89	1.03	0.98	0.75	0.84	0.19
Iso-α-acids / (mg/L)		19.98	17.65	18.32	17.02	16.93	16.28	6.28
Total acid / (mL/100 mL)		2.0	1.6	1.8	1.5	1.9.	2.2	1.2
Total polyphenols (mg/L)		206	209	212	195	210	203	102

Based on Table 3.0, comparison and analysis of general indicators between six IPA beers and regular beer lead to the following conclusions: compared with commercially available light-refreshing beer, the original wort gravity of the IPA beers brewed in this thesis is generally 12–14°P, while light-refreshing beer has a lower original wort gravity; due to the difference in original wort gravity, the alcohol content of IPA beer is also higher than that of light-refreshing beer, around 5%, which directly shows a stronger mouthfeel in tasting; regarding color, the range is 6.5–9.0 EBC, and IPA beer is close to regular beer—if caramel malt or black malt is used in IPA beer, color can be further increased; due to the addition of a large amount of high-quality hops and additional hop input into the fermenter during fermentation using dry hopping technology, bitterness ranges from 27.5–32.8 BU, far higher than regular beer, so IPA beer bitterness is more obvious; α-acids and iso-α-acids are significantly higher in IPA beers than in regular beer; total polyphenols are also significantly higher, related to the large hop addition in IPA beer.

7.2.2 Comparison of Flavor Substances Between IPA Beer and Regular Beer

According to the above operations, brew IPA beer. Analyze multiple important flavor substances in six tanks of IPA beer and compare them with commercially available light-refreshing beer. The results are shown in Table 3.1:

Table 3.1 Comparison of Flavor Substances Between IPA Beer and Light-Refreshing Beer

Test item	Lagering-stage beer indicators	IPA Beer						Light-refreshing beer
		1#	2#	3#	4#	5#	6#
Linalool (μg/L)		25.21	26.98	27.58	30.25	29.07	28.46	1.96
α-Terpineol (μg/L)		5.12	4.96	7.06	6.25	6.08	7.62	1.12
Geraniol (μg/L)		8.87	9.53	11.25	9.60	10.14	8.02	2.59
β-Citronellol (μg/L)		20.04	18.96	22.47	19.86	20.56	21.75	2.08
n-Propanol (μg/L)		16.386	19.698	20.026	17.602	18.869	22.052	12.860
Isoamyl alcohol (μg/L)		69.423.	71.056	65.324	68.752	70.230	72.026	52.362
Isobutanol (μg/L)		15.985	16.320	16.226	17.146	15.842	14.762	10.650
Ethyl acetate (μg/L)		29.362	30.056	27.223	32.002	27.968	28.541	14.259
Isoamyl acetate (μg/L)		4.726	5.036	4.239	4.052	5.224	4.863	1.820

Based on Table 3.1, comparison and analysis of aroma substance contents between six IPA beers and regular beer lead to the following conclusions: the four aroma substances in hops—linalool, α-terpineol, geraniol, and β-citronellol—are the main hop-derived aroma substances that can dissolve into beer fermentation liquid. From the table, linalool content remains around 25–30 μg/L. Compared with 1.96 μg/L linalool in light-refreshing beer, IPA beers are more than 10 times higher. A similar situation occurs for β-citronellol. The other two aroma substances α-terpineol and geraniol are also significantly higher in IPA beer, about 4–5 times those of light-refreshing beer. These comparisons indicate that hop aroma in IPA beer is significantly better than in regular beer, which is a typical feature of IPA beer. Since IPA beer is developed based on top-fermented Ale wheat beer, IPA beer has typical wheat beer characteristics: higher alcohols and esters are much higher than in light-refreshing beer. In mouthfeel, this directly appears as a fuller body and richer fruity aroma. In summary, the hop aroma and ester aroma of IPA beer are more intense and prominent than those of regular light-refreshing beer, highlighting the advantages and characteristics of IPA beer.

7.3 Summary of This Chapter

According to the scheme studied in this thesis, a 1000 L IPA beer brewing experiment was conducted. Basic indicators and flavor substance contents of IPA beer were tested and compared with commercially purchased light-refreshing beer. Professional beer industry personnel evaluated that: IPA beer shows obvious style differences from regular light-refreshing beer. Since IPA beer is developed based on top-fermented Ale wheat beer, IPA beer shows many characteristics of the latter, such as white, rich and fine foam, fuller body, rich fruity ester aroma, thicker mouthfeel than regular beer, and higher alcohol content than regular beer, which appears as a stronger taste. The α-acid content in IPA beer is higher than in regular beer, related to hop addition during post-fermentation; incomplete dissolution of α-acids can cause slightly turbid beer body. Compared with regular beer, the biggest feature of IPA beer is the prominent hop aroma. It brings a stronger sensory impact in smell and taste, showing rich floral and fruity aromas, producing a pleasant aroma and mouthfeel for the taster.

Chapter 8 Discussion and Outlook

8.1 Discussion

In this experiment, IPA beer was developed based on the top-fermented Ale brewing process combined with the dry hopping technology that is rarely applied domestically. Since IPA beer has almost no corresponding commercial products launched in China’s beer market, the development of IPA beer in this thesis is still at a relatively preliminary exploratory stage. The aim is to find a relatively reasonable production method for IPA beer. Many technical aspects of brewing were not studied in depth in a targeted manner, but the work can provide a basis for future brewing of IPA beer and form a good foundation for subsequent detailed research.

For IPA beer, the role of hops is very important. Aroma substances in hops have a great influence on beer flavor. Therefore, it is very necessary to select suitable hop varieties and hop dosages. Regarding dry hopping technology, the exploration of hop types and dosages added in this experiment is also at an early stage. The hop varieties in the experiment were relatively few, making it difficult to accurately find the most ideal hops. As a result, the hop flavor of the beer may not be perfect, but it is highly characteristic. Because this experiment mainly pursued an optimization exploration of the process, the pursuit of technical details was not fully in place. For example, detailed discussion on hop addition methods during fermentation was not conducted, and very specific experiments on the timing of hop addition were not performed. These issues will inevitably be addressed in subsequent future research.

8.2 Outlook

With the increasingly intense competition in China’s beer market, the transformation of the domestic beer industry is inevitable. For domestic beer producers, product innovation and quality improvement will certainly become top priorities. As the public’s requirements for beer quality increase, beer products need further improvement from quality to packaging to meet consumers’ growing psychological demands, and developing new products becomes the best means to seize market opportunities.

The golden age of traditional bottom-fermented light-refreshing beer is coming to an end. With improved consumer purchasing power and global exchange of beer culture, fresher and better beer varieties will inevitably exert huge market impact on traditional light-refreshing beer. For practitioners in the beer industry, this is both an opportunity and a challenge.

The IPA beer discussed in this experiment is one of the relatively novel products in China. It belongs to top-fermented Ale beer, characterized by emphasizing typical hop aroma and relatively rich ester aroma. For ordinary domestic consumers, there are almost no corresponding products of this type on the market. Whether it is the typical hop floral aroma or the rich fruity ester aroma, both are fresh and worthy of tasting. IPA beer is only one of many new varieties. With cooperation under economic globalization, exchange of new beer products worldwide will become more convenient and closer, and more and more similar products will occupy the domestic market. It is believed that under the tireless efforts and innovation of practitioners in China’s beer industry, China’s beer industry will certainly reach a new level.