Evaluation of vegetable sauerkraut quality during storage based on convolution neural network.

Vegetable sauerkraut is a traditional fermented food. Due to oxidation reactions that occur during storage, the quality and flavor in different periods will change. In this study, the quality evaluation and flavor characteristics of 13 groups of vegetable sauerkraut samples with different storage time were analyzed by using physical and chemical parameters combined with electronic nose. Photographs of samples of various periods were collected, and a convolutional neural network (CNN) framework was established. The relationship between total phenol oxidative decomposition and flavor compounds was linearly negatively correlated. The vegetable sauerkraut during storage can be divided into three categories (full acceptance period, acceptance period and unacceptance period) by principal component analysis and Fisher discriminant analysis. The CNN parameters were fine-tuned based on the classification results, and its output results can reflect the quality changes and flavor characteristics of the samples, and have better fitting, prediction capabilities. After 50 epochs of the model, the accuracy of three sets of data namely training set, validation set and test set recorded 94%, 85% and 93%, respectively. In addition, the accuracy of CNN in identifying different quality sauerkraut was 95.30%. It is proved that the convolutional neural network has excellent performance in predicting the quality of Szechuan Sauerkraut with high reliability.

Phototreatment (below 1100 nm) improving quality attributes of fresh-cut fruits and vegetables: A review.

The emerging area of phototreatment technology has shown a significant potential to enhance the quality of fresh-cut fruit and vegetable products (FFVP). This review critically evaluates relevant literatures to address the potential for phototreatment technology (Red, blue, green, ultraviolet and pulsed light) applied to FFVP, outline the key to the success of phototreatment processing, and discuss the corresponding problems for phototreatment processing along with research and development needs. Base on photothermal, photophysical and photochemical process, phototreatment displays a great potential to maintain quality attributes of FFVP. The operating parameters of light, the surface properties and matrix components of the targeted material and the equipment design affect the quality of the fresh-cut products. To adapt current phototreatment technology to industrial FFVP processing, it is necessary to offset some limitations, especially control of harmful substances (For example, nitrite and furan) produced by phototreatment, comparison between different phototreatment technologies, and establishment of mathematical models/databases.

Progress in Extrusion-Based Food Printing Technology for Enhanced Printability and Printing Efficiency of Typical Personalized Foods: A Review.

Three-dimensional printing technology enables the personalization and on-demand production of edible products of individual specifications. Four-dimensional printing technology expands the application scope of 3D printing technology, which controllably changes the quality attributes of 3D printing products over time. The concept of 5D/6D printing technology is also gradually developing in the food field. However, the functional value of food printing technology remains largely unrealized on a commercial scale due to limitations of printability and printing efficiency. This review focuses on recent developments in breaking through these barriers. The key factors and improvement methods ranging from ink properties and printer design required for successful printing of personalized foods (including easy-to-swallow foods, specially shaped foods, and foods with controlled release of functional ingredients) are identified and discussed. Novel evaluation methods for printability and printing precision are outlined. Furthermore, the design of printing equipment to increase printing efficiency is discussed along with some suggestions for cost-effective commercial printing.

3D printed white radish/potato gel with microcapsules: Color/flavor change induced by microwave-infrared heating.

The feasibility of using microwave-infrared heating (MIR) to stimulate color/flavor changes of 3D-printed white radish and potato gels containing lipid-soluble natural pigment and essence microcapsules was investigated. Natural red gromwell pigment and rose essence were microencapsulated using gum Arabic/maltodextrin/ß-cyclodextrin as the wall materials and spray drying as the drying method. The microcapsules were incorporated into white radish and potato powder at different mass ratios (0, 0.3, 0.7, 1, and 2%, w/w) and the mixture were used as 3D printing ink. The storage modulus and loss modulus of printing paste were decreased with the increasing microcapsule addition; however, the viscosity was not significantly affected. The texture properties (hardness, springness, chewiness, and gumminess) of printed samples after MIR were increased significantly. The color and flavor of the samples changed in a microcapsule concentration- and heating time-dependent manner. With the prolongation of heating time, the brightness value (L*) of the printed sample added with microcapsules was decreased, while the redness (a*) and yellowness value (b*) were significantly increased. The results of electronic nose showed that the flavor of 2% (w/w) microcapsule samples was significantly different before and after heating, and the signals of sensors S1, S4, S5, S9, S11, S14, S16, S17 increased significantly after heating. This research has provided insights for the development of novel 3D printed foods with bright colors and unique flavors.

Inhibition of nitrite in prepared dish of Brassica chinensis L. during storage via non-extractable phenols in hawthorn pomace: A comparison of different extraction methods.

The objective of this study was to investigate whether non-extractable phenols (NEP) prepared by acid, enzymatic and alkaline hydrolysis in hawthorn pomace could reduce the nitrite content in prepared vegetable dishes (PVDs), analyzed through ultraviolet spectrophotometry and high performance liquid chromatography. The results showed that on the seventh day of storage, compared with the control group, the nitrite content of the samples added with acid, enzymatic and alkaline hydrolyzed NEP decreased by 40%, 28% and 19%, respectively, depending on different contents and chemical compositions of the recovered NEP. The nitrite reduction caused by NEP was mainly attributed to the growth inhibition of microorganisms producing nitrite (e.g., Escherichia coli and Pseudomonas aeruginosa) and the direct scavenging effect on nitrite, rather than affecting the activities of nitrate reductases and nitrite reductases in plant tissues. Use of hawthorn pomace is potentially a promising option to reduce nitrite in PVDs.

Internal structure design for improved shape fidelity and crispness of 3D printed pumpkin-based snacks after freeze-drying.

This study aimed to use the internal design of 3D food printing (3DFP) technology to obtain freeze-dried pumpkin with controllable crispness and higher shape fidelity. Two internal structural variables, namely filling pattern (honeycomb, rectilinear, grid, and triangular) and filling rate (25, 50, 75, and 100%), were studied to assess the impact on the shape fidelity and crispness characteristic of the product. As the filling rate decreased, the printing accuracy of the samples increased. Regardless of the filling patterns, the 75% filled samples exhibited the greatest deformation. The crispness of the samples was closely related to the filling pattern and filling rate. In the case of the high filling rate, the internal structure of the samples was dense. It was less likely to be broken under the action of force and the crispness was reduced. In addition, the internal structure of the sample influenced its physical properties, and the crispness customization of the product can be achieved by designing the porosity. Morphological differences between printed and cast samples suggested that 3DFP was beneficial for the processing and preparation of highly viscoelastic materials. The crispness of cast sample was obviously less than that of the 100% filled printed samples. The results opened an interesting perspective to create crisp foods with high shape fidelity that meet specific texture requirements and provide new sensory perceptions.

Garlic essential oil microcapsules prepared using gallic acid grafted chitosan: Effect on nitrite control of prepared vegetable dishes during storage.

In order to lower the nitrite content in prepared vegetable dishes (PVDs) within a week, microcapsules loaded with garlic essential oils (GEO) were prepared using modified chitosan (CS) with different mass ratios of gallic acid (GA) to CS, and their physicochemical properties were determined. The effects of GEO alone and of microcapsules made using native CS and GA-CS (GA-grafted CS) with the highest conjugation degree on the nitrite content in PVDS were measured quantitatively. Also, the reasons for the differences were identified. The results showed that the microcapsules prepared using GA-CS (at a mass ratio of 0.5:1) presented the best physicochemical properties, including antioxidant activity, encapsulation efficiency, sustained release, etc. GA-CS microcapsules enhanced growth inhibition of bacteria producing nitrites, thus showing its excellent ability to inhibit nitrites, compared to GEO alone and microcapsules made using native CS. GA-CS encapsulation is a new option to lower the nitrite content in PVDs.

New developments on ultrasound-assisted processing and flavor detection of spices: A review.

Spices are widely used to add unique flavors to food; such uniqueness may, however, suffer significant loss during processing, which is in many cases needed to preserve or transform spices into food ingredients. Here, the effects of ultrasound-assisted drying, extraction and microencapsulation on flavor of spices along with selected progresses made on ultrasonic detection of the flavor are reviewed. Flavors of some spices, e.g., laurel, onion and peppermint, dried with the aid of ultrasound are noted to be better than those of shade-dried, infrared, microwave and hot-air dried products. Ultrasound-assisted extraction can be effectively used to extract essential oils or oleoresins from spices. Compared with selected extraction methods, the variety of flavor substances obtained via ultrasound-assisted extraction is richer and their concentrations are also higher, making the flavors of the extracts stronger. Ultrasound-assisted microencapsulation has noted to increase the compound embedding and loading ratios, resulting in better maintenance of flavor over a longer period of time. Ultrasound has finally proved to be an efficient, green, economical and sensitive flavor detection technology for spices.