The UN's Food and Agriculture Organization (FAO) has a report on food price instability in Latin America. It notes a number of problems, such as interrelation with energy and financial markets, information problems, demand in Asia, climate change, and others. It also notes the problem of oligopolies that not only affect prices but also don't necessarily address the food needs of the population. This latter point is particularly important, since it becomes a source of political instability.
El alza y la volatilidad de los precios internacionales de los alimentos se produce en un contexto de crisis económica que implica menores oportunidades de empleo e ingreso, lo que agudiza el impacto sobre la seguridad alimentaria. Asimismo, el contexto de crisis financiera genera gran incertidumbre y falta de confianza, lo que amplifica la volatilidad y dificulta las medidas de política pública.
Food inflation is currently higher than general inflation, though there is clear volatility:
It's funny how these days there is a relentless push in the media to portray Latin America in entirely positive economic terms, ignoring issues like this. That follows a previous trend of viewing everything in Latin America as negative and violent.