Advanced Biotech Peach Thiazole 1% WS-PG, Natural 1338 is a natural, tan to brown liquid with a nutty, peach odor. This product is soluble in water and in most organic solvents. Peach Thiazole 1% WS - PG, Natural 1338 is most commonly used in the preparation of food and beverage flavorings. is a natural, tan to brown liquid with a nutty, peach odor. This product is soluble in water and in most organic solvents. Peach Thiazole 1% WS - PG, Natural 1338 is most commonly used in the preparation of food and beverage flavorings.