Table II: Rate constants for various values of percent lost.
Percent Lost (%)	Rate Constant (k)	Percent Lost (%)	Rate Constant (k)	Percent Lost (%)	Rate Constant (k)	Percent Lost (%)	Rate Constant (k)
10	0.00059	23	0.00145	36	0.00248	49	0.00374
11	0.00065	24	0.00152	37	0.00257	50	0.00385
12	0.00071	25	0.00160	38	0.00266	51	0.00396
13	0.00077	26	0.00167	39	0.00275	52	0.00408
14	0.00084	27	0.00175	40	0.00284	53	0.00419
15	0.00090	28	0.00183	41	0.00293	54	0.00431
16	0.00097	29	0.00190	42	0.00303	55	0.00444
17	0.00104	30	0.00198	43	0.00312	56	0.00456
18	0.00110	31	0.00206	44	0.00322	57	0.00469
19	0.00117	32	0.00214	45	0.00332	58	0.00482
20	0.00124	33	0.00222	46	0.00342	59	0.00495
21	0.00131	34	0.00231	47	0.00353	60	0.00509
22	0.00138	35	0.00239	48	0.00363	--	--

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Table III: Temperature factors used for determining rate of a-acid lost at various storage temperatures.
Temperature (C) * (F)	Factor	Temperature (C) * (F)	Factor	Temperature (C) * (F)	Factor	Temperature (C) * (F)	Factor
20 * 68	1.000	7 * 44.6	0.548	-6 * 21.2	0.301	-19 * -2.2	0.165
19 * 66.2	0.955	6 * 42.8	0.524	-7 * 19.4	0.287	-20 * -4	0.157
18 * 64.4	0.912	5 * 41	0.500	-8 * 17.6	0.274	-21 * -5.8	0.150
17 * 62.6	0.871	4 * 39.2	0.477	-9 * 15.8	0.262	22 * -7.6	0.144
16 * 60.8	0.831	3 * 37.4	0.456	-10 * 14	0.250	-23 * -9.4	0.137
15 * 59	0.794	2 * 35.6	0 435	-11 * 12.2	0.239	-24 * -11.2	0.131
14 * 57.2	0.758	1 * 33.8	0.416	-12 * 10.4	0.228	-25 * -13	0.125
13 * 55.4	0.724	0 * 32	0.397	-13 * 8.6	0.218	-26 * -14.8	0.119
12 * 53.6	0.691	-1 * 30.2	0.379	-14 * 6.8	0.208	-27 * -16.6	0.114
11 * 51.8	0.660	-2 * 28.4	0.362	-15 * 5	0.198	-28 * -18.4	0.109
10 * 50	0.630	-3 * 26.6	0.345	-16 * 3.2	0.189	-29 * -20.2	0.104
9 * 48.2	0.602	-4 * 24.8	0.330	-17 * 1.4	0.181	-30 * -22	0.099
8 * 46.4	0.574	-5 * 23	0.315	-18 * -0.4	0.173	-	-

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Table IV: Storage factors for primary storage methods.
Storage Conditions	Storage Factor
Not sealed or sealed in poly bags	1*
Sealed in barrier packaging, airtight jars, but not free from oxygen	0.75**
Sealed in barrier packaging, airtight jars under vacuum or inert atmosphere such as nitrogen or carbon dioxide	0.5***
*No Adjustment required. **Estimated median value for median-quality storage method. ***Value derived experimentally

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Backup Math

The percent lost number is derived from the hop storage index (HSI) or is measured directly (9). These data are generally provided by hop brokers and researchers. If you know the HSI for a variety, you can calculate the percent lost by using the following formula (5):      %Lost=log(HSI/0.25)*110 where log is the base 10 logarithm. The k value (or rate constant) is calculated according to the following formula (6):      k = (lnAo - lnAN)/180 where ln is the natural logarithm, AO is the original a-acid value, and AN is the new a-acid value after 180 days. Now you may ask, "How do I get the original a and new a values?" As it turns out, you don't need to know. If you know the percent lost you can calculate AO and can assume any arbitrary number for AN. Calculate AO (for any value of AN) using the following formula (7): AO = (AN*100)/(100*%Lost) The reason AN can be any arbitrary number is that all we are really calculating here is a ratio, based on percent lost. Just make sure that when you go back to the k calculation you use the same arbitrary number you used to calculate AO. The temperature factor (TF) is based on the research that showed that the rate of deterioration is halved for every 15 °C (27°F) drop in temperature (1). This is an exponential curve, and I simply used Excel's curve-fit algorithms to fill in the data points, using 20 °C (68°F) as the point at which no adjustment is necessary (because this is the point at which the data are measured). What I have not done is to calculate a temperature factor for values above 20 °C (values >1) because the table was getting fairly large, and you really shouldn't be storing your hops anywhere near this temperature anyway. The storage factor (SF) is based on interpretations of the data presented in the references. A factor of 1 means no adjustment, again correlating with the measurements of percent lost.

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