Ustinova's doctor called the appearance of sediment after opening the kvass an alarming signal.

The appearance of sediment in the kvass after opening the bottle may indicate that the drink has begun to deteriorate. Elena Ustinova, a therapist and nutritionist at the SM Clinic, warned about this on August 9.

"The use of spoiled kvass can lead to food poisoning and other unpleasant health consequences. At the same time, it is often possible to determine that the drink has gone bad before the first sip," the expert said in an interview with RT.

First of all, the doctor advises to pay attention to the smell. Natural kvass should have a characteristic bread flavor with a slight sourness. A sharp, unpleasant or unusual smell may indicate spoilage of the drink.

Another sign is changes in taste. According to Ustinova, excessive acidity, bitterness or other atypical taste should be a reason to stop using kvass. The doctor also recommended evaluating the appearance of the drink. Normally, kvass has an amber or brownish tint. If the liquid has become cloudy, changed color, or looks unusual, it should not be consumed.

Special attention should be paid to sediment. As Ustinova noted, the appearance of sediment after opening a bottle or while storing a drink outside the refrigerator is an alarming sign. The use of spoiled kvass can lead to food poisoning. Possible symptoms include nausea, vomiting, diarrhea, abdominal cramps, and fever.

If there is a significant loss of fluid, there is a risk of dehydration and disruption of the water-electrolyte balance. This may be accompanied by weakness and dizziness, and in some cases, cardiac arrhythmias.

Backup: how to replace mayonnaise and sweet soda

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Nutritionist Olga Panova told on August 4 what is the danger of using mayonnaise. According to Panova, you should be especially careful about store-bought sauces, which often use cheap vegetable oils and stabilizers. The expert called for controlling the portion size and reserving mayonnaise for rare cases.