The internal structures of frozen materials and the formation of bubbles significantly affect the physical properties of such materials as ice cream. Various measurement techniques including optical and scanning electron microscopies, and X-ray microcomputed tomography have been employed to observe bubbles and the internal structures of frozen samples. However, these measurement techniques revealed only a limited measurement range and low resolution. The objectives of this work were to develop a cryogenic microtome spectral imaging system (CMtSIS) to measure microscale to macroscale with respect to bubbles and internal structures formed in some frozen materials. The CMtSIS, which consisted of a microtome, automatic high-precision XY stage and a near-infrared (NIR) spectral imaging system, enable the capture of consecutive cross-sectional images of a frozen sample exposed by multi-slicing with a minimum thickness of 0.001 mm and a maximum area of 60×60 mm. Bubbles in an ice cream sample were identified as defocused spots in two-dimensional (2D) CMtSIS images due to the difference in the focal distance created by the vacant spaces. NIR images of ice crystals in the frozen sample appeared darker than the other components at 1500 nm due to weak reflected light at this peak wavelength. Milk solids were also observed by the flux differences in light reflected from the different interfaces in the ice cream.
Monitoring of water activity at meat surface is important on controlling the quality of aging beef, because the fermentation microorganisms are grow on the meat surface. Although in previous study water activity of beef under drying process was investigated by near infrared (NIR) spectra, spectra data have been obtained from the whole beef cut. Therefore, this study aimed to estimate water activity of the surface of the sample using NIR spectra in the 700-1050 nm. Different thick samples in the 2-10 mm were prepared and the optimization of the measurement conditions was carried out for surface monitoring. Consequently, the optimal measurement condition were determined for monitoring the spectra from the surface of a beef cut. The change in moisture content and water activity about lump sample of beef were investigated for drying at 4℃. A linear decrease in water activity estimated by NIR spectra was observed, and the estimated water activity reached 0.8 after around 22～25 days. These results showed the evaluation potential of dry state at surface of beef by using NIR spectroscopy.
Mume fruit, Japanese apricots (Prunus mume Sieb. et Zucc.), have traditionally been used for pickles, juice, and liqueur in Japan. During the pickling of mume fruit, an exudate fluid from the fruit called umesu (or umezu) is produced as a byproduct. We developed laboratory-scale and factory-scale methods using synthetic absorbents HP-20 column chromatography to prepare phenolic fractions from umesu (umesu phenolics or umezu phenolics, hereafter referred to as UPs). In this study, we obtained six batches of UPs using a factory-scale method, and their chemical features were examined. The phenolic contents were 13.1±0.8% and 19.2±2.1%, respectively, with gallic acid and p-coumaric acid as standards. The total sugar content was 57.7±4.7%. Very close similarity was observed in the high-performance liquid chromatograms and compositions of the phenolics in the six batches of UPs. The four major phenolic compounds found in the alkaline hydrolysate of UPs were caffeic acid, cis-p-coumaric acid, trans-p-coumaric acid, and ferulic acid. Some batches showed high amounts of cis-p-coumaric acid / total p-coumaric acid. Since this isomerization did not occur during the UP preparation process, it seems likely that isomerization of trans-p-coumaric acid into cis-p-coumaric acid occurred due to sunlight irradiation during umesu storage.
Palm oil santan is a healthier coconut milk replacement made from Palm oil. It was developed by the Malaysian Palm Oil Board (MPOB) in order to cater and to increase healthy food demand in Malaysia. In this study, we examined the growth and behavior of three yogurt starter cultures; Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus when they were inoculated into palm oil santan. All three starter cultures grew to 8–9 log(cfu/ml) in palm oil santan and fitted with a logistic-like growth model. Interestingly, L. acidophilus shows diauxic growth behaviour; an uncommon growth pattern usually found in substrates rich with sugar carbohydrates whereas palm oil in santan is a lipid substrate.