While unopened cooking oils typically have a shelf life of 18 to 24 months, this date, according to HK01, only applies to sealed containers completely isolated from air. Once opened and exposed to air, the fatty acids in the oil begin to oxidize. This process leads to rancidity and spoilage, producing harmful byproducts like peroxide, aldehyde, and ketone over time.
To prevent oxidation and spoilage, food and nutrition experts recommend specific usage timelines based on experimental data. Large 5-liter cooking oil bottles should ideally be consumed within 42 days of opening. Smaller 1-liter bottles should be used within 28 days of opening. Adhering to these guidelines minimizes prolonged air exposure, which causes oxidation and spoilage.
Research indicates that for common 5-liter cooking oil bottles, with daily opening and closing, the peroxide value (an oxidation indicator) can exceed safety standards between day 42 and day 63. For smaller 1-liter bottles, this threshold can be crossed between day 28 and day 56 after opening.
Four clear signs indicate severe spoilage in stored cooking oil, meaning it should not be used:
A pungent odor: A distinct rancid, burnt, or stale smell that irritates the nose.
Changed state: The oil, initially clear, becomes cloudy. Sediment may appear at the bottom, or distinct upper and lower layers may form.
Unusual taste: A bitter or acrid flavor when tasted.
Loss of aroma: The oil completely loses its natural fragrance.
Doctors warn that if spoiled oil with elevated peroxide levels is consumed occasionally, a healthy adult's body can typically process and eliminate the toxins without immediate severe damage. However, continuous consumption of substandard oil can lead to cumulative damage, causing persistent irritation to the gastrointestinal lining. This may result in symptoms such as nausea, vomiting, abdominal pain, and diarrhea. Prolonged intake also carries other potential health risks.
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To prevent oxidation and spoilage, 5-liter bottles of cooking oil should be consumed within 42 days, and 1-liter bottles within 28 days of opening. Photo: Bui Thuy |
My Y (Source: HK01)
