Yoshihiro Chuda

Effects of Physiological Changes in Potato Tubers (Solanum tuberosum L.) after Low Temperature Storage on the Level of Acrylamide Formed in Potato Chips

Acrylamide in potato chips made from tubers stored at 2 or 20°C for two weeks after harvest was analyzed by GC-MS. The acrylamide level in the former chips was higher than ten times of that in the latter, which was highly correlated with both glucose and fructose levels in the tubers.

Effects of Storage Temperature on the Contents of Sugars and Free Amino Acids in Tubers from Different Potato Cultivars and Acrylamide in Chips

To clarify the effects of storage temperature on potato components and acrylamide in chips, tubers from five cultivars were stored at various temperatures (2, 6, 8, 10, and 18 °C) for 18 weeks, and the contents of sugars, free amino acids in tubers, and acrylamide in chips after frying were analyzed. At temperatures lower than 8 °C, the contents of reducing sugars increased markedly in all cultivars, with similar increases in the acrylamide level and dark brown chip color. Free amino acids showed little change at the storage temperatures tested and varied within certain ranges characteristic of each cultivar. The contents of reducing sugars correlated well with the acrylamide level when the fructose/asparagine molar ratio in the tubers was <2. When the fructose/asparagine ratio was >2 by low-temperature storage, the asparagine content, rather than the reducing sugar content, was found to be the limiting factor for acrylamide formation.

Change in content of sugars and free amino acids in potato tubers under short-term storage at low temperature and the effect on acrylamide level after frying.

Changes in the sugar and amino acid contents of potato tubers during short-term storage and the effect on the acrylamide level in chips after frying were investigated. The acrylamide content in chips began to increase after 3 days of storage at 2 °C in response to the increase of glucose and fructose contents in the tubers. There was strong correlation between the reducing sugar content and acrylamide level, R2=0.873 for fructose and R2=0.836 for glucose. The sucrose content had less correlation with the acrylamide content because of its decrease after 4 weeks of storage at 2 °C, while the reducing sugar in potato tubers and the acrylamide in chips continued to increase. The contents of the four amino acids, i.e., asparatic acid, asparagine, glutamic acid and glutamine, showed no significant correlation with the acrylamide level. These results suggest that the content of reducing sugars in potato tubers determined the degree of acrylamide formation in chips. The chip color, as evaluated by L* (lightness), was correlated well with the acrylamide content.

Acrylamide in Japanese processed foods and factors affecting acrylamide level in potato chips and tea

Acrylamide concentrations in processed foods sold in Japanese markets were analyzed by LC-MS/MS and GC-MS methods. Most potato chips and whole potato-based fried snacks showed acrylamide concentration higher than 1000 microg/kg. The concentrations in non-whole potato based Japanese snacks, including rice crackers and candied sweet potatoes, were less tha. 350 microg/kg. Those in instant precooked noodles were less than 100 microg/kg with only one exception. The effect of storage condition of potato tubers on acrylamide concentration in potato chips after frying was also investigated. Sugar content in the tubers increased during cold storage, and the acrylamide concentration increased accordingly. The concentrations of asparagine and other amino acids, however, did not change during the cold storage. High correlations were observed between the acrylamide content in the chips and glucose and fructose contents in the tubers. This fact indicated that the limiting factor for acrylamide formation in potato chips is reducing sugar, not asparagine content in the tubers. Effects of roasting time and temperature on acrylamide concentration in roasted green tea are also described.

Identification of the forms of boron in seaweed by 11BNMR

Abstract Free and complex forms of accumulated borate in seaweeds were identified by 11B N M R. The NMR spectra of green and red algae showed boric acid peaks mainly. In contrast, brown algae gave two distinctive peaks predominantly containing borate diesters. To identify the moiety coupled to borate, borate complexes with compounds containing vicinal hydroxy groups, such as mannitol, laminarin and alginic acid, were prepared and examined. The results strongly indicated that mannitol formed the main diester complexes. The signal of the complexes was decreased rapidly after storage. Fresh brown algae, therefore, contain large amounts of B-carbohydrate complexes as do higher plants.

The state analysis of NaCl in snow crab (Chionoecetes japonicus) meat examined by 23Na and 35Cl nuclear magnetic resonance (NMR) spectroscopy

To assess the contribution of NaCl to seafood tastiness, 23Na and 35Cl nuclear magnetic resonance (NMR) spectroscopy was used to determine the mobility of sodium and chloride ions in intact snow crab (Chionoecetes japonicus) leg meat. The T1 (longitudinal relaxation time) values of both 23Na and 35Cl, obtained from inverse recovery experiments, show an evident variance with different heat-processing methods. Heating tends to inhibit both sodium and chloride ion mobility. 35Cl NMR spectra indicate that chloride exists in two different chemical states, one derived from free ions and the other from organic base complexes. © 2000 Society of Chemical Industry