This paper examines the innovative history of a number of multinational agri-food companies using a database for utility patents and design patents. The first hypothesis to be tested is whether firms that innovate, usually do it persistently. We analyse a sample of 16,698 patents granted in the US over the period 1977-1994 to 103 F&B firms selected from the world's largest food and beverage multinationals (FBMs). The main conclusion that stems from these series is that only a small number of spells last for more than 4 yr. That is, only 6% of all utility patenting spells are ongoing after 4 yr, and only 1.6% of all design patenting spells are ongoing after 4 yr. Nevertheless, it is significant that there are 22 utility patents spells of the longest duration (18 yr). This frequency is only comparable to 3 yr long spells in utility patents and it is completely different from the design patents (there is only one 18 yr spell). However, this myriad of short-term projects coexist with long-run innovation. There is a small nucleus of persistent patentors who contribute around 80% of the total number of patents granted to the multinational agri-food sector. Persistent patentors are also heavy patentors since length of spells and average number of patents per year are statistically associated. Length of innovative spells is not associated, by contrast, with size of the company or specific agri-food subsector. Companies remaining innovative in the technical field tend also to remain innovative in design for long periods of time. (C) 2002 Elsevier Ltd. All rights reserved.
