Food and the free market?

The market, through competition, is supposed to bring increased efficiency and lower prices. But the effect of turning food production over to the market has been to produce less competition, and offer more structural power to the largest companies. Consumers suffer as a result. According to a recent study, market concentration has led to higher food prices for consumers in 24 of 33 sectors in the US. Farmers suffer too: as agricultural economist C. Robert Taylor testified to the Senate Agricultural Committee in 1999, 'Since 1984, the real price of a market basket of food has increased by 2.8 per cent, while the farm value of that food has fallen by 35.7 per cent.'

Source: Stuffed and Starved, p. 104

I've half-jokingly labelled the book Stuff and Starved as Cooking for Commies, and it's definitely left-of-center politically. Yet at the same time there were a lot of points to ponder in the book, the quote above being only one.

Do you agree with the above blurb that the current "free" market system in the agricultural industry is functioning poorly, or perhaps that the increased portion of the pie held by agricultural conglomerates is due to people eating more processed foods?