Effects of Flavonoids and Ascorbic Acid Derivatives on Non-enzymatic Browning in Peaches

Abstract

Non-enzymatic browning (NEB) due to ascorbic acid degradation is one of the most common reasons the shelf life of many processed foods is reduced. Different methods to minimize or retard the formation of browning pigments have been studied; however, to date, refrigeration is still the most preferable. Unfortunately, the use of low temperatures to preserve food is not always available in many parts of the world. Indeed, an area of concern due to NEB has been identified in meal-ready-to-eat (MRE) individual military rations, specifically diced peaches with syrup. This product was once part of soldiers' menus; however, it was removed due to browning and textural deterioration that occurred when stored under field conditions. We examined two general approaches to reduce NEB: the replacement of ascorbic acid by a more stable form and the use of flavonoids as antibrowning antioxidants in peach systems. These approaches were studied in three objectives. In our first objective, ascorbyl-2-phosphate showed better stability than ascorbic acid at 40°C in peach puree model systems, but not at 50 or 60°C. In the second objective, after the evaluation of the effect of two forms of vitamin C (ascorbic acid and ascorbyl-2-phosphate) and Pycnogenol (0%, 0.01% and 1%) on the quality of diced peaches in retortable pouches, we concluded that neither ascorbyl-2-phosphate nor pycnogenol resulted in improved color or ascorbic acid stability. Finally, in our third objective, after the evaluation of the effect of peach source (fresh, individually quick frozen and canned), addition of calcium chloride, and the addition of a water soluble flavonoid (°-glucosylrutin, °-GR) in diced peaches packaged in retortable pouches stored at 24, 40 and 51°C, there were no significant effects of °-GR on any of the peach sources at 51°C. However, at 40°C, °-GR improved the quality of diced peaches in pouches made of individually quick frozen and canned peaches, but not for fresh peaches. Quality was assessed by color (CIELAB system), which was measured using a handheld colorimeter, and ascorbic acid levels of peaches, which was determined using high performance liquid chromatography.