Input (grade 13): Prior to Heinz (and his fellow innovators), commercial tomato ketchups of that time were watery and thin, in part due to the use of unripe tomatoes, which were low in pectin.
Output (grade 6): Prior to Heinz (and his fellow innovators), commercial tomato ketchups of that time were watery and thin. This was due to the use of unripe tomatoes.