Terahertz (THz) wave has a unique character that other range waves do not have, and its application is widely studied. Technology relating THz wave, such as generation, detection and application, remarkably develops in recent. Many studies about application of THz wave to food analysis have been performed. This review explains the basics of THz wave as well as application of THz wave to food analysis. Moreover, statistical method in treatment of THz spectrum is reported.
The influences of low intensity ultrasound and ohmic heating on Sake yeast were investigated. The results showed that low intensity ultrasound promoted the growth of Sake yeast K-7 and increased the rate of glucose consumption and ethanol production. After ultrasonic irradiation, a significant increase of intracellular uptake was observed. The promotion effect on growth was frequency dependent. In addition, the ultrasonic irradiation during the exponential phase showed the strongest influence and during the stationary phase the influences were not obvious. During ohmic heating treatment, the rate of glucose consumption and ethanol production was increased and the promotion effect on cell growth was slightly higher at 3 kHz than that of 60 Hz. However, the influence of electricity consumption on cell growth was not obvious. Meanwhile, the combined effect of ultrasound and ohmic heating on the growth of Sake yeast was slightly higher than those of separate treatments.
The moisture sorption isotherms of durum semolina were observed in the temperature range of 30 to 80°C for both the sorption and desorption processes. The isotherms of its constituent starch and gluten were observed at 30°C and that of spaghetti was observed at 60°C. All the isotherms were well expressed by the Guggenheim-Anderson-de Boer equation. The isotherm for the desorption process lay over that for the sorption one at any temperature, and a slight hysteresis was recognized. Isosteric heats, q, for sorption and desorption processes were estimated according to the Clausius-Clapeyron equation as a function of the moisture content of durum semolina. The q values were larger at lower moisture contents, indicating that water molecules more strongly interact with the wheat flour at lower moisture contents. The q values for the desorption process were greater than those for sorption. The isotherms of starch lay over those of gluten at any water activity, and those of spaghetti were located between those of starch and gluten.
A model of through-flow drying was developed in order to simulate the drying properties of beds packed with tobacco cut-filler placed in a flow of air or wet air mixed with superheated steam. This model was simplified as follows: (1) the fluid in the bed is regulated as plug flow; (2) a piece of the cut-filler is taken to have a plane-sheet shape; (3) the internal movement of water in the cut-filler is regarded as a rate-limiting step; and (4) the transfers of mass and heat are specified by a set of one-dimensional equations of convection and diffusion. In a wide range of 373 to 523 K, the calculated curves of moisture content and temperature of the tobacco were in agreement with experimental values. It was concluded that the model is valid and applicable to the estimation of drying properties of tobacco materials.
Polysaccharides in sweet corn cob may have many bioactivities. In this study, an efficient ultrasound-assisted extraction (UAE) technique has been developed to recover crude polysaccharides from sweet corn cob (SCCP). Ultrasound power was determined at 250 W based on the single factor test, extraction temperature (40 − 60°C), duration (30 − 60 min) and ratio of volume to weight (20 − 40 mL·g-1) were then chosen to further optimize extraction conditions by response surface methodology (RSM). The statistical analysis revealed that the optimal conditions to obtain the highest yield of SCCP were of 54.7°C, 42.8 min and 27.9 mL·g-1, and the polysaccharide extraction yield (0.56%) obtained from optimized UAE proved its higher efficiency when compared with the conventional method. Also, the results showed that the extraction of polysaccharides followed first-order kinetics model well.
Chemical compositions and anti-oxidative characteristics of non-fermented and fermented beverages and associated solid by-products produced from freeze-dried sweet potato roots were examined. Freeze-dried roots of purple-fleshed variety Quandow had higher total phenolics (9.32 mg g-1) and total flavonoids (1.54 mg g-1) contents and greater antioxidant activity (60.05 mg g-1) than orange-fleshed variety Tainung 66 (1.14, 0.43 and 20.77 mg g-1 of total phenolics, total flavonoids and antioxidant activity, respectively). Fermented and non-fermented beverages and solids produced from Quandow also had higher antioxidants contents and greater antioxidant activities than those produced from Tainung 66. Thus, producing non-fermented or fermented beverages from purple-fleshed variety Quandow has commercial potential and this will increase its economic value. The purple-fleshed variety Quandow also produced high carbohydrate or high protein solid by-products enriched with antioxidants during beverage processing, which may be used as dietary carbohydrate supplements (non-fermented solids) or high protein animal feed (fermented non-alcoholic solids).
TEMPO STA is based on traditional most probable number technique and is a test for use with the TEMPO system for an automated enumeration of coagulase-positive staphylococci in 24 h in food products. In this study, TEMPO STA was compared with Baird-Parker (BP) agar which is the most cited medium in reference methods for the enumeration of coagulase-positive staphylococci in cheese. A method comparisons study was conducted both artificially and naturally contaminated cheese samples. Pearson correlation coefficients were determined as 0.875 and 0.897 between the two methods for naturally and artificially contaminated samples, respectively. In general, absolute differences did not exceed one log between results obtained by the two methods. According to intra-laboratory reproducibility standard deviation of two methods, TEMPO STA was more precise than BP agar. The results of this study showed that TEMPO STA is an efficient alternative method for the enumeration of coagulase-positive staphylococci in cheese.
Soybean protein is an important plant protein source; its two major constituents, 7S and 11S, account for more than 70% of its total protein. in this study, the soybean 7S and 11S fractions were enzymatically hydrolyzed by Bacillus subtilis strains from traditional fermented foods, and the hydrolysates were analyzed using immunoblotting and an amino acid analyzer. According to the immunoblotting, the main components and allergens of 7S and 11S were degraded into smaller units. Large amounts of free amino acids (FAA) released in diverse profiles were also detected. B. subtilis SB3 and SB5 released more total FAA than other strains. Therefore, these B. subtilis strains may have potential for application in the production of hypoallergenic soybean foods rich in FAA.
Rice grains contain starch degrading enzymes, including α-glucosidases, α-amylases, β-amylases, pullulanase and isoamylases. To investigate the elution behavior of these enzymes from rice grains into cooking water during rice cooking, we separated cooking water from rice grains after soaking (20°C) and when the temperature reached 40°C and 60°C during cooking. Immunological detection of these enzymes in rice grains and cooking water was carried out with SDS-PAGE and immunoblot. Bands corresponding to pullulanase, α-glucosidase, isoamylase 1, and α-amylase E were detected in both rice grains and cooking water at each temperature. Bands corresponding to α-amylases A + B and H were not detected in rice grains, but were detected in the cooking water at each temperature. The β-amylase band was detected in rice grains but was not detected in cooking water. These results suggest that the amount of enzyme eluted into cooking water depends on enzyme localization and quantity in rice grains.
Novel peptides derived from chicken collagen hydrolysate (CCH) were confirmed to have a vasoprotective effect after ingestion and absorption to vessels; however, their endovascular mechanism of action required clarification. Therefore, using human umbilical vein endothelial cells (HUVECs), in which inflammation had been induced by tumor necrosis factor-α (TNF-α), we investigated the mechanism by which CCH-derived peptides inhibited the vascular inflammatory response. Expression of soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and interleukin-8 (IL-8) in HUVECs was increased significantly by the addition of TNF-α, whereas treatment with proline-hydroxyproline (Pro-Hyp) and hydroxyproline-glycine (Hyp-Gly), which are present in human peripheral blood after ingestion of CCH, inhibited these increases. These peptides also reduced the mRNA expression of inducible nitric oxide synthase (iNOS) up-regulated by TNF-α. These results suggest that the vasoprotective effect of CCH-derived peptides is due to inhibition of endothelial inflammation.
The green discoloration of garlic (Allium sativum L.) puree, a serious problem in garlic processing, was investigated. Two thiosulfinates, 2-propenyl E-1-propenethiosulfinate (2P1PTS) and (E/Z)-1-propenyl 2-propenethiosulfinate (1P2PTS), were isolated from unheated garlic puree (homogenate), and were confirmed to be the direct causal constituents (‘color developer’) of green discoloration based on a color developing assay. 2P1PTS and/or 1P2PTS were reacted with glycine to develop a blue-green color similar to the discoloration of garlic purees. 2P1PTS and 1P2PTS showed synergy for greening; the color developing activities of three solutions, 2P1PTS, 1P2PTS and an equimolar mixture of them (0.5-2P1PTS + 0.5-1P2PTS; similar to the natural abundance ratio) were in the rank order: (0.5-2P1PTS + 0.5-1P2PTS) > 2P1PTS > 1P2PTS.
Polyphenol fractions from twenty-three honey samples of various floral origins were extracted with an Amberlite XAD-2 column, and total polyphenol content and antioxidant properties were determined. The Folin-Ciocalteu method was used to determine total polyphenol content, and antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Total polyphenol content per 100 g of honey ranged from 17.5 mg (Japanese prickly-ash) to 132.8 mg (peppermint). Peppermint honey had the highest flavonoid content (48.3 mg/100 g) and exhibited the highest antioxidant activity of all samples. A positive linear correlation was observed between honey color and DPPH radical scavenging activity. p-Coumaric acid and kaempferol were isolated and identified as antioxidants from peppermint honey. Additionally, quantification of these compounds in other honey samples was carried out. Peppermint honey contained a large amount of p-coumaric acid (705 μg/100 g) and kaempferol (471 μg/100 g). The potent antioxidant activity of peppermint honey is attributable to the quantities of these compounds, especially kaempferol.
Stability of fucoxanthin was assessed in dried Undaria pinnatifida (wakame). After 210 days storage of dried wakame in the dark at 50°C, the stability of fucoxanthin was higher than that of purified fucoxanthin incubated at both 20°C and 40°C. Furthermore, we analyzed the stability of fucoxanthin in scones containing 0.5 − 2 wt% commercial dried wakame powder. More than 85% of the fucoxanthin remained unchanged in the scones after heating the dough at 190°C for 30 min. Sensory analysis indicated that although the addition of wakame powder darkened the appearance and strengthened both the taste and smell of the scones, they remained acceptable. Furthermore, overall sensory scores showed that scones containing 0.5 wt% and 2 wt% wakame powder were more favorable than control scones.
This study aims to evaluate the effects of spices essential oils (SEOs) on the microbial populations in chilled pork stored in PE film antimicrobial package. The microbiota from the pork under different storage conditions were studied by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) of the V3 variable region of the 16S rRNA, followed by sequencing of DGGE fragments. We found that SEOs resulted in an overall significant reduction of viable counts of Gram positive bacteria such as Carnobacteria, Enterococcus sp., Staphylococcus sp. and Brochotrix thermosphacta compared to the control. A 2.5 log cycles reduction of enterobacteria was also identified compared to the control during storage, while SEOs had little effect on Pseudomonas sp. the total volatile basic nitrogen (TVBN)and Thiobarbituric acid reactive substance(TBARS) were affected by the use of SEO packages, but color (L*, a*, b*), shear force and cooking loss were not affected. The bacteriostatic effect of clove EO was the best among all the SEOs tested, and the number of spoilage populations decreased with the use of the SEOs, but the species diversity of spoilage microbiota was not affected.
The loss of quality or quantity of raw foods caused by spoilage bacteria is a major problem, especially in developing countries. Evaluation of the frequency and level of bacterial contamination and/or identification of the contaminating bacteria are keys to solving this problem. The objective of this study was to evaluate the prevalence and types of contaminating bacteria in retail foodstuffs in Thailand. Foods in four categories (137 samples total) including meat (51 samples), vegetables (38 samples), fish or seafood (37 samples) and fermented food (11 samples) were purchased randomly from seven different open markets and seven supermarkets in Thailand from August 2010 to March 2011. Indicator bacteria of fecal contamination or other naturally contaminating bacteria were isolated and identified. More than 90% of each category of collected retail meat, vegetables and fish or seafood was contaminated with coliform bacteria. The contamination rate of fecal coliform bacteria, Staphylococcus spp. and lactic acid bacteria was higher in vegetables from open markets than those from supermarkets, and the contamination rate of Staphylococcus spp. was likewise higher in fish or seafood samples purchased from open markets than those from supermarkets. Improvement in hygienic practices throughout the food distribution may reduce the risk of food poisoning and spoilage of foods purchased in Thai markets.
The purpose of this study was to select a lactic acid bacterial strain for use as a starter culture for producing fermented meat products and for evaluating the survival ability in the gastrointestinal tract. Five strains of lactic acid bacteria were isolated from funazushi, a traditional fermented fish product in Japan, and their bile and simulated digestive juice tolerances were evaluated to screen their survival in gastrointestinal tracts. Growth in a ground meat patty was evaluated by counting viable cells and measuring pH. Lactobacillus plantarum JAB2001 was capable of growth on 10 % NaCl and exhibited tolerance to bile acids and simulated gastrointestinal juices. After incubation with this strain at 25°C for 48 h a ground beef patty showed pH values of about 4.8 and lactic acid bacterial counts at the 109 level per gram of patty. Coliform bacteria and Staphylococcus aureus were unable to proliferate in the meat patty with strain JAB 2001, which is thus suitable for use as a starter culture of fermented meat products.
Thirteen elements (Na, Mg, P, Ca, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Cd and Ba) in the compositions of 230 taro samples (118 Japanese fresh, 35 Japanese frozen, 36 Chinese fresh and 41 Chinese frozen) were determined by ICP-AES and ICP-MS. Linear discriminant analysis and a support vector machine were used on the compositions. A discriminant model to detect Chinese taro from those of Japan was constructed with Mg, Ni, Zn, Rb and Cd. Receiver operating characteristics and sampling plans were examined to improve discrimination ability. The sensitivity for Chinese fresh and frozen taro was estimated to be 79.4% and 73.2%, with false positive rates of 1.7% and 2.5% for Japanese fresh and frozen taro, respectively.
Ibaranori (Hypnea charoides), a red alga, grows along the coast of the Japanese islands and is commonly eaten in southwestern areas such as Okinawa Prefecture. While H. charoides is thought to be a health-promoting food, the underlying mechanism of this benefit is not well understood. In this study, in order to examine the health benefits of H. charoides, a hot water extract was evaluated for its anticoagulant activity by using thromboelastography and measuring the hypocholesterolemic effect on hypercholesterolemic rats administered the hot water extract orally. The extract significantly exerted anticoagulant activity, as indicated by changes in thromboelastogram parameters and suppression of the increase in rat liver cholesterol ester and rat serum cholesterol. Based on these results, the health benefits of H. charoides as a useful food resource and the potential for effective use of the alga are suggested.
Nano-scale structures of individual single molecules and supra-molecular networks of xanthan gum were investigated using atomic force microscopy (AFM). AFM images of xanthan dissolved in water at ambient temperatures revealed branched fibrous structures, the cross-sectional dimensions of which typically ranged from 1 to 1.5 nm. Individual molecular chains, the cross-sectional dimensions of which were around 0.5 nm, were observed after heating at 90°C. Renaturation behavior upon successive cooling was dependent on the concentration of xanthan and the temperature. At 60°C, the formation of an anti-parallel double-stranded helix from an isolated molecule was evident. Air-drying of aqueous solutions containing either 1 or 10 μg/mL xanthan at room temperature resulted in the formation of nanometer- or micrometer-sized networks, respectively. These networks appeared to be composed of multiple filaments aggregated in parallel alignment to form thicker bundles with varied thicknesses, typically ranging from 0.5 to 2 nm.
Changes in chemical, textural, and volatile flavor properties were investigated for mackerel fish (Scomberomorus niphonius) stored in cold rooms (5°C and 0°C) and freezers (−20°C and −55°C). Correlation and multivariate analysis showed a significant time-dependent relationship between total volatile base nitrogen (TVBN)/ trimethylamine (TMA) (Y) and storage time (X) for fish stored in cold rooms, with R = 0.996 − 0.997 values of Gompertz model (Y = a*exp(−exp(b − cX)), and there was a good linear relationship between TVBN and TMA. Combined with the textural properties, the polynomial fitting model (Y = a + bX + cX2 +…, R = 0.982 − 0.991) was applied and elucidated the correlation between the hardness/springiness (Y) and TVBN (X), the rational function model (Y = (a + bX)/(1 + cX + dX2), R = 0.975 − 0.979) used for the chewiness (Y) and TVBN (X). The electronic nose analysis revealed that the variation of muscle volatile flavor compounds was found out along the PC1 to the right, and then along the PC2 to the upward and further to the downward based on the principal component analysis (PCA). Furthermore, the linear discriminant analysis (LDA) had better distinction effect for the changes of fish flavor than PCA. Results from this study suggested that the texture analysis in combination with electronic nose techniques might be utilized as a rapid expeditious process for predicting quality and shelf life of the fresh fish or other aquatic products.
The effects of oral ingestion of a hot water extract of prune (Prunus domestica L.) fruit on allergic responses were investigated in mite-sensitized BALB/c mice. The number of sneezing events in mice given the extract-added diet was significantly lower than in mice given the extract-free diet. Serum mite allergen-specific immunoglobulin E levels were significantly lower in mice given the extract-added diet than in mice given the extract-free diet. In contrast, the ratio of splenic IFN-γ+CD4+ cells/IL-4+CD4+ cells was higher in mice given the extract-added diet. Expression levels of Stat6, Btk and Stim1 mRNAs in spleen cells of mice given the extract-added diet were significantly lower than in mice given the extract-free diet. These results suggest that the prune extract may reduce type I allergic symptoms in mice via the adjustment of type 1 helper T cell/type 2 helper T cell balance and the suppression of mast cell degranulation.