Yoshio Makino

Modified atmosphere packaging of fresh produce with a biodegradable laminate of chitosan-cellulose and polycaprolactone

Abstract Use of a biodegradable laminate of a chitosan-cellulose and polycaprolactone as a film for modified atmosphere packaging (MAP) of fresh produce was tested. The temperature dependence of O2, CO2 and N2 gas permeability coefficients for the biodegradable laminate was examined. The coefficients increased linearly with increasing temperature in the range 10–25 °C. The coefficients were validated by experiments on MAP with shredded lettuce and shredded cabbage. MAP systems with head lettuce, cut broccoli, whole broccoli, tomatoes, sweet corn and blueberries were designed using the gas permeability coefficients. The gas composition in each biodegradable package including the fresh produce was simulated to be close to the optimal composition. The biodegradable laminate was found suitable as a packaging material for storage of fresh produce.

Rapid detection of Escherichia coli contamination in packaged fresh spinach using hyperspectral imaging.

A rapid method based on hyperspectral imaging for detection of Escherichia coli contamination in fresh vegetable was developed. E. coli K12 was inoculated into spinach with different initial concentrations. Samples were analyzed using a colony count and a hyperspectroscopic technique. A hyperspectral camera of 400-1000 nm, with a spectral resolution of 5 nm was employed to acquire hyperspectral images of packaged spinach. Reflectance spectra were obtained from various positions on the sample surface and pretreated using Sawitzky-Golay. Chemometrics including principal component analysis (PCA) and artificial neural network (ANN) were then used to analyze the pre-processed data. The PCA was implemented to remove redundant information of the hyperspectral data. The ANN was trained using Bayesian regularization and was capable of correlating hyperspectral data with number of E. coli. Once trained, the ANN was also used to construct a prediction map of all pixel spectra of an image to display the number of E. coli in the sample. The prediction map allowed a rapid and easy interpretation of the hyperspectral data. The results suggested that incorporation of hyperspectral imaging with chemometrics provided a rapid and innovative approach for the detection of E. coli contamination in packaged fresh spinach.

Non-invasive analytical technology for the detection of contamination, adulteration, and authenticity of meat, poultry, and fish: A review

The requirement of real-time monitoring of food products has encouraged the development of non-destructive measurement systems. Hyperspectral imaging is a rapid, reagentless, non-destructive analytical technique that integrates traditional spectroscopic and imaging techniques into one system to attain both spectral and spatial information from an object that cannot be achieved with either digital imaging or conventional spectroscopic techniques. Recently, this technique has emerged as one of the most powerful and inspiring techniques for assessing different meat species and building chemical images to show the distribution maps of constituents in a direct and easy manner. After presenting a brief description of the fundamentals of hyperspectral imaging, this paper reviews the potential applications of hyperspectral imaging for detecting the adulteration, contamination, and authenticity of meat, poultry, and fish. These applications envisage that hyperspectral imaging can be considered as a promising non-invasive analytical technique for predicting the contamination, adulteration, and authenticity of meat, poultry, and fish in a real-time mode.

Non-destructive evaluation of ATP content and plate count on pork meat surface by fluorescence spectroscopy.

The potential of fluorescence spectroscopy was investigated for the non-destructive evaluation of ATP content and plate count on pork meat surface stored aerobically at 15 °C during three days. Excitation (Ex) Emission (Em) Matrix of fluorescence intensity was obtained and fluorescence from tryptophan (Ex=295 nm and Em=335 nm) and NADPH (Ex=335 nm and Em=450 nm) was detected. Because tryptophan and NADPH fluorescence changed along with the growth of microorganisms, microbial spoilage on meat could be detected from fluorescence. By applying PLSR (Partial Least Squares Regression) analysis, ATP content and plate count were predicted with good determination coefficient (0.94-0.97 in calibration and 0.84-0.88 in validation).

Parsimonious model development for real-time monitoring of moisture in red meat using hyperspectral imaging.

A hyperspectral imaging system in the spectral range of 400-1000 nm was investigated to develop a multispectral real-time imaging system allowing the meat industry to determine moisture content in red meat including beef, lamb, and pork. Multivariate calibration models were developed using partial least-squares regression (PLSR) and least-squares support vector machines (LS-SVM) in the full spectral range. Instead of selection of different sets of feature wavelengths for beef, lamb, and pork, a set of 10 feature wavelengths was selected for convenient industrial application for the determination of moisture content in red meat. A quantitative linear function was then established using MLR based on these key feature wavelengths for predicting moisture content of red meat in an online system and creating moisture distribution maps. The results reveal that the combination of hyperspectral imaging and multivariate has great potential in the meat industry for real-time determination of moisture content.

A Theoretical Model for Designing Modified Atmosphere Packaging with a Perforation

A theoretical model based on the kinetic molecular theory of gases for predicting gas exchange through a polymeric film with a perforation was developed, and its feasibility for design of modified atmosphere packaging (MAP) systems was discussed. Simulated gas flux through perforations was closely approximated to experimental data at three levels of temperature and under two types of initial gas conditions. Changes in the gas compositions in polymeric pouches with a perforation was fairly predicted using the proposed model. Atmospheric changes in MAP systems with perforations for two kinds of fresh produce were also predicted very well by the proposed equations. The model proposed in the present study was valid for the design of MAP systems.

Accumulation Mechanism of γ-Aminobutyric Acid in Tomatoes (Solanum lycopersicum L.) under Low O2 with and without CO2

The storage of ripe tomatoes in low-O(2) conditions with and without CO(2) promotes γ-aminobutyric acid (GABA) accumulation. The activities of glutamate decarboxylase (GAD) and α-ketoglutarate-dependent GABA transaminase (GABA-TK) were higher and lower, respectively, following storage under hypoxic (2.4 or 3.5% O(2)) or adjusted aerobic (11% O(2)) conditions compared to the activities in air for 7 days at 25 °C. GAD activity was consistent with the expression level of mRNA for GAD. The GABA concentration in tomatoes stored under hypoxic conditions and adjusted aerobic conditions was 60-90% higher than that when they are stored in air on the same day. These results demonstrate that upregulation of GAD activity and downregulation of GABA-TK activity cause GABA accumulation in tomatoes stored under low-O(2) conditions. Meanwhile, the effect of CO(2) on GABA accumulation is probably minimal.

Stimulation of γ-Aminobutyric Acid Production in Vine-Ripe Tomato (Lycopersicon esculentum Mill.) Fruits under Modified Atmospheres

Stimulation of gamma-aminobutyric acid (GABA) production under low O2 and high CO2 conditions (adjusted aerobic atmosphere) under which ethanol fermentation could be avoided was studied. Vine-ripe tomato fruits were stored under hypoxia conditions and adjusted aerobic atmospheres as well as in the air at 15 degrees C for 13 days and at 30 degrees C for 6 days. At 30 degrees C tomato fruit GABA concentration under the adjusted aerobic atmosphere (O2 11%, CO2 9%) was significantly higher by 48% than that in air after 6 days from the start of storage. Increased accumulation of alanine under the adjusted aerobic atmosphere supports the observation that this atmosphere stimulates GABA production. The results demonstrate that the concentration of GABA as a beneficial substance for antihypertensive effects and so on can be increased by storing tomato fruits under adjusted aerobic atmospheres for the first time.

Oxygen Consumption Model for Fresh Produce on the Basis of Adsorption Theory

An O2 consumption model for fresh produce was proposed based on the Langmuir adsorption theory in order to design a modified atmosphere packaging (MAP) system. To examine the usefulness of the proposed model, the O2 consumption rate data of fresh produce were applied to the model. The model was found to be suitable for describing the respiration of several kinds of fresh produce. Mathematical analysis of the MAP system for shredded lettuce was done from the proposed rate equation and the basic material balance. The simulated results agreed with the experimental data. The O2 consumption model was found to be useful for the design of the MAP system.

Hyperspectral imaging in tandem with multivariate analysis and image processing for non-invasive detection and visualization of pork adulteration in minced beef

Pork adulteration in minced beef was detected for the first time using a hyperspectral imaging (HIS) technique. Minced beef samples were adulterated with minced pork in the range of 2–50% (w/w) at approximately 2% intervals. Images were acquired using a visible near-infrared hyperspectral imaging (VNIR-HSI) system and their spectral data were extracted. Several data pre-treatments and different linear multivariate analyses, namely partial least squares regression (PLSR), principal component regression (PCR), and multiple linear regression (MLR), were investigated to determine the predictive ability of VNIR-HSI in detecting pork meat adulteration in minced beef. PLSR had a better performance than PCR for predicting pork adulteration in minced beef. Only four wavelengths centered at 430, 605, 665, and 705 nm were selected as the important wavelengths to build the MLR model for visualizing the distribution of adulteration. The results confirm that HSI can be used to provide a rapid, low cost, and nondestructive testing technique for detection of adulteration in minced meat.