Oncom

Oncom is a mold-fermented food and one of the traditional staples of Sundanese cooking in West Java, Indonesia. It is made largely from the leftovers of other food industries, which makes it a clear example of using every part of a raw material.

History

Oncom has long been part of the everyday diet of West Java, although the sources available do not establish precisely when or where it first appeared. Its technique relies on fermentation with fungi, the same family of processes behind tempeh, to which it is closely related.

The raw material is usually what remains from other productions: soy pulp left after making tofu, peanut press cake once the oil has been pressed out, cassava residue after the starch is extracted (pati singkong), or coconut press cake from oil pressing or coconut milk production. Relying on these by-products improves the efficiency of the local food economy.

There are two main kinds. Black oncom is made with Rhizopus oligosporus, the fungus used for tempeh, while red oncom uses Neurospora intermedia var. oncomensis, and it is the only traditional human food produced from Neurospora.

Culture

In West Java oncom is an everyday food, found on family tables and in popular cooking. It is fried as gorengan, cooked in a banana leaf parcel as pepes, or roasted, seasoned and mixed with steamed rice in the dish known as nasi tutug oncom.

It also fills traditional snacks such as comro, a popular Sundanese treat whose name comes from oncom di jero, meaning "oncom inside", and appears in lontong and arem-arem rice dumplings.

Food safety matters in its making. The aflatoxin-producing mold Aspergillus flavus can be present in peanut press cake, and coconut press cake can harbor Burkholderia gladioli, which produces highly toxic compounds. Hygiene during production is therefore essential, and the best substrate for making oncom safely is still not known.

Trivia