Because, while in 1960 only dates for bottled beer were given, the 1980 one also includes draught beer. Which had a shelf life four days longer. It also says which beers could only be sold in bottled form. Seven of them, which are easy enough to spot in the table as they have no draught shelf life specified: Aubi, Extra, Diabetiker-Pils, Deutsches Pilsner Spezial, Märzen, Weizenbier and Deutscher Porter.
The eagle-eyed amongst you might have spotted that Berliner Weisse is missing. Perhaps that's because its shelf life was so much longer. In the 1960 version it's given as 270 days.
For some popular beers, the period is shorter than in 1960. Deutsches Pilsner is down from 15 days to 10. Vollbier Hell and Dunkel from 12 days to 8 days. Bockbier Hell and Dunkel from 15 days to 10. Doppel-KarameIbier from 90 days to 30.
Why do some styles have much longer periods? Because they were pasteurised. It's these specific types: Aubi, Doppel-KarameIbier, Diabetiker-Pils, Deutsches Pilsner Spezial and Märzen.
|1980 DDR beer shelf life in days|
|Aubi||90||—||without sediment or cloudiness|
|Deutsches Pilsner Spezial||90||—|
|Weißer Bock or Bockbier Hell||10||14|
|Dunkler Bock or Bockbier Dunkel||10||14|
|Dunkel (Einfachbier)||9||13||without fermentation or souring; light sediment allowed|
|1980 TGL 7764, page 11.|