What is the preponderant opinion of scholars regarding the determination of usurious commodities, and does the condition of storage, stipulated by the Malikis for usurious foodstuffs, fall away in our time due to the existence of refrigerators?

The preponderant view is that the 'illah (underlying reason) for riba (usury/interest) in gold and silver is their monetary value (as mediums of exchange), based on the Prophet's (peace be upon him) saying: "A dinar for a dinar, there is noفضل (extra amount) between them, and a dirham for a dirham, there is no فضل between them." As for the 'illah for riba in the other four categories mentioned in the hadith (wheat for wheat, barley for barley, dates for dates, and salt for salt), it is edibility combined with being measurable by volume (kil) or weight (wazn). This means that riba applies to every edible item that can be measured by volume or weight.

Riba does not apply to vegetables or fruits sold by count, such as pomegranates and watermelons. It does apply to milk and oils because liquids are measured by volume.

It must be taken into consideration that the standard for volume and weight is what was prevalent during the time of the Prophet (peace be upon him), based on his saying: "The weight is the weight of the people of Makkah, and the measure is the measure of the people of Madinah."