Fluorescence fingerprint imaging is a technique that combines the fluorescence fingerprint with imaging, and can be used to visualize the distribution of constituents in foods and other materials. The fluorescence fingerprint, also known as the excitation-emission matrix (EEM), is a set of fluorescence spectra acquired at consecutive excitation wavelengths. Due to its use of multiple excitation wavelengths, the fluorescence fingerprint is suited to measure samples that contain many constituents. Here, we introduce two applications of fluorescence fingerprint imaging: visualization of gluten and starch in bread dough, and imaging of gluten, starch and fat in pie pastry.

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We evaluated the effect of processing (i.e., boiling, salting, and washing) on the trace element composition of wakame (Undaria pinnatifida), to accurately assess the geographical origin of wakame products on the market. The trace element composition (Mg, P, Ca, V, Mn, Fe, Zn, As, Rb, Se, Cd, and Ba) was significantly altered by processing, likely due to (1) elimination and/or dilution of the elements during processing, (2) contamination from salts, and (3) decrease of wakame content per unit weight by salting. However, the Ba content of wakame was relatively resistant to the elimination and contamination effects during processing, and the effect of dissolution could be corrected by a simple calibration. These results suggest that Ba content can be employed as a reliable factor to distinguish the geographical origin of wakame, even after processing. Indeed, the Ba content in wakame and wakame products from China (25.6±5.7ppm) is much greater than that from other sources (i.e., Sanriku: 8.6±1.9ppm, Naruto: 10.9±2.3ppm, and South Korea: 14.2±4.6ppm), allowing for the discrimination of sources (i.e., China and others) of wakame and wakame products by 90.0% and 95.9%, respectively.

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We prepared salted radish roots and analyzed the changes in γ-aminobutyrate (GABA) and glutamate decarboxylase (GAD) activity during dehydration and long-term salting. The amounts of glutamate (Glu) and GABA in the fresh roots were 5.72±0.23 and 0.28±0.01mg/g dry weight (DW), respectively. The amount of GABA by sun-drying and salt-pressing process increased to 7.30±1.57 and 4.98±0.06mg/g DW, respectively. In contrast, the Glu content decreased to 0.71±0.13mg/g DW. The GABA content in salted radish was further increased by 1.2-3.0-fold by the addition of monosodium glutamate (MSG, 0.1-0.5% weight of the radish) at the same time of salting. Fresh radish showed the highest GAD activity, which decreased during the dehydration and salting process. On the other hand, in the liquid leached from the radishes during the salting process (agari-mizu in Japanese) with MSG, a time-dependent decrease of Glu and increase of GABA were observed. Thus, it was suggested that Glu was converted to GABA by microorganisms in the agari-mizu and transferred to the salted radish. The color of the salted radish without MSG was pale yellow, while that with MSG turned grayish in color after 2 months of salting.Thus, the addition of MSG during the salting process decreased the shelf-life of the product.

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We investigated changes in flavonoids and hydrophilic oxygen radical absorbance capacity (H-ORAC) values in six varieties of spinach among two or three cultivation periods. Two varieties of spinach were cultivated in 2 periods (4/6∼5/19 and 9/22∼11/14). Four varieties were also cultivated from 7/27 to 9/1 in addition to the two periods. Total flavonoids, H-ORAC values of spinach cultivated in 9/22∼11/14 were higher than those cultivated in 4/6∼5/19, in accordance with SPAD values indicating chlorophyll content. These results demonstrated that fall cultivation of spinach, in which the temperature declines toward the harvest date, enhances the flavonoids and antioxidant activity of spinach with a dark green color.

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The purpose of the present study was to apply a new method of producing high-quality dried grapes by microwave irradiation of pulp followed by hot air drying. This method was previously established in the production of semi-dried Japanese pear fruit. Microwave irradiation of grapes shortened the proceeding hot air drying period by sixty percent. Both skin color (yellow-green and red) and original flavor (such as muscat and foxy) were not entirely lost in the dried grape products. The texture of dried grape products from thin-skinned cultivars, which hardly slip off, was better than products from slip-skin cultivars.

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