Frederick Hengl looked frail as he entered his plea, and his lawyer has requested he receive medical attention, according to U-T San Diego.
Police said they responded to neighbours' complaints about a foul odour coming from the couple's two-bedroom, bungalow-style house on Friday morning.
The first officer entered the home through a window and saw three pans of meat cooking on the stove that turned out to be parts of the victim, 73-year-old Anna Faris.
It's believed Faris was killed sometime in November. Authorities have not yet determined how she died.
There were numerous pieces of freshly cut bone found around the home, said Deputy District Attorney Katherine Flaherty. A meat grinder, a saw, a boning knife and other cutting materials were also in the house.
Flaherty said there was no evidence of cannibalism.
Neighbour Erick Chavez told U-T San Diego that the stench from the house grew unbearable after someone placed a fan in one of the home's windows. The odour had lingered for more than a week.
Hengl remained jailed on $5m bail. An effort to leave a phone message for his public defender on Wednesday night was unsuccessful.