In recent decades, glucosinolates and isothiocyanates have attracted the interest of scientific community due to healthy properties of these bioactive compounds and their role as natural antimicrobials and anticarcinogenic agents. However, these compounds can lose their properties and transform into antinutrients depending on processing conditions. At this stage of investigation, there is a need in evaluation of the commonly accepted and new emerging methods in order to establish the optimum conditions for preserving healthy glucosinolates and isothiocyanates. This paper reviews the conventional and new promising technologies that can be useful for extraction of appropriate glucosinolates and isothiocyanates from natural sources (i.e., Brassica vegetables). The impact of different preservation processes on degradation of glucosinolates and isothiocyanates is also discussed.

/pdf/the-effects-of-conventional-and-non-conventional-processing-36y23bv2sv.pdf

The Effects of Conventional and Non-conventional Processing on Glucosinolates and Its Derived Forms, Isothiocyanates: Extraction, Degradation, and Applications

This paper discusses novel technologies and their applications in the world. Two surveys were independently designed and conducted by a North American (Survey 1) and by a European group (Survey 2). The respondents were food professionals from industry, academia and government. The questions sought to identify novel technologies either applied now or with the potential to be commercialised in 5–10 years, commercialisation factors, associated regulations and limitations. In Survey 1, HPP (80%), microwave (88%) and UV (84%) were the main technologies applied now and anticipated in the next 5 years. PEF was third instead of UV in Survey 2. The main drivers were higher quality products (94%), product safety (92%) and shelf life (91%). HPP and microwaves were identified as main technologies now and in the next 10 years. There were geographical differences with North America finding UV and radiation, and Europe finding PEF of more importance now. Cold plasma and PEF were anticipated to be more important in Europe in 10 years' time while HPP, microwave and UV remained more important to North America. Industrial relevance The emerging technologies mentioned in the survey have been developing since the early 20th century or before. However, they are not adopted on any large scale such as canning or heat pasteurisation. This study was conducted on a worldwide scale to determine current uses for emerging technologies in different food sectors. Some technologies are deemed of more commercial importance in certain countries than others. HPP and microwave heating are the two main technologies currently on commercial applications. PEF is more popular in Europe, especially the Netherlands where a commercial scale unit exists. On the contrary, microwave technology seems to be popular in all countries but the Netherlands. UV and radiation are more important in North America than Europe. Pressure and CO 2 is only deemed to be of commercial importance in North America.

Mapping trends in novel and emerging food processing technologies around the world

Bactericidal effect of various non-thermal plasma agents and the influence of experimental conditions in microbial inactivation: A review

Fruit and vegetable juices are rich sources of nutrients that support microbiological growth and ultimately undergo rapid deterioration of safety and quality. The loss of nutritional quality of juices due to intensive thermal processing is a major problem encountered during the treatment of commercially preserved liquid foods. Conventional thermal processing technologies inactivate microorganisms and enzymes and extend the shelf life of foods but exert negative effects on nutritional and organoleptic properties of juices, for example, a loss of vitamins, of a desirable flavor, and of bioactive compounds and development of different sensory profiles as a result of heating. Nonthermal technologies including ultrasonication, a pulsed electric field, high-pressure processing, irradiation, and their combinations are suitable alternatives for achieving the same preservation effect without the adverse effects of heat on the quality of juices and meet consumer demand for clean-label, safe, and wholesome products without compromising their nutritional properties.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12336

The Impact of Nonthermal Technologies on the Microbiological Quality of Juices: A Review.

Enzymatic browning is associated to the colour alteration and phenolic degradation of minimally-processed fruits and vegetables. The main responsible is polyphenol oxidase (PPO, EC 1.14.18.1), a copper-containing oxidoreductase which catalyzes two different enzymatic reactions involving oxygen and polyphenolic substrates which are polymerized to dark pigments. Since the control of PPO activity is until now an open question in the agro-food industry, the search for new anti-browning strategies is moving towards replacing conventional treatments. The present review is aimed to discuss non-thermal technologies and natural inhibitors considering their anti-PPO impact in relation to enzyme source, processing conditions, type and concentration of bioactive compounds. These innovative treatments can be proposed as eco-friendly systems for effectively reducing PPO activity thus preventing enzymatic browning and consequently improving sensory, antioxidant and nutritional properties of fruit and vegetable products.

Recent advances in controlling polyphenol oxidase activity of fruit and vegetable products

A review of kinetic models for inactivating microorganisms and enzymes by pulsed electric field processing

Pulsed electric field (PEF) technology is a promising nonthermal processing techniques that can be utilized to inactivate microorganisms in liquid food with high-voltage PEF. Herein, a high-voltage solid-state switch consisting of 64 insulated gate bipolar transistors (IGBTs) connected in series was designed and developed for the PEF treatment. Regarding the unbalanced sharing of voltage in series-connected IGBTs, the resistor–capacitor–diode snubber circuit was specifically used and investigated in terms of model of parameters. Furthermore, using gate drivers and optic fiber, the driving circuit and protection circuit were designed and validated. A 50-kV isolation level power supply was built in order to provide 16 independent IGBT stacks with 24 V of power each. The results show that the developed switch works adequately a delay time of 380 ns with 35.8-kV voltage and 44.8-A current capacity. Moreover, the response time of the short-circuit protection is acceptable as well with a reaction time of under $7~\mu \text{s}$ . In conclusion, the switch designed for PEF treatment of liquid food performs within set parameters and is ready for pilot-scale processing capability.

A High-Voltage Solid-State Switch Based on Series Connection of IGBTs for PEF Applications

The utility model discloses a high voltage pulse electric field processing chamber for garden stuff osmotic dehydration pretreatment. A metal shell is supported by a base carrier, first filter cloth and second filter cloth are fixed on the upper potion and the lower portion of an insulation cavity in the metal shell respectively through supports, a grounding electrode is fixedly embedded in the insulation cavity and located below the first filter cloth, a plurality of symmetrically-arranged tracks are arranged at the position, located below the grounding electrode, above and below the two sides of the insulation cavity respectively, a high voltage electrode is installed on any track on the two sides of the insulation cavity, air outlet tubes and air inlet tubes are installed on the tops of the metal shell and the insulation cavity and the bottoms of the metal shell and the insulation cavity respectively, two tube openings are respectively provided with a thermoelectric couple, and the high voltage electrode and the grounding electrode are respectively connected with a high voltage pulse generator. According to the high voltage pulse electric field processing chamber, a pulse electric field can be formed in an air region, garden stuff is directly processed, the working procedures are reduced, and cost is saved; in the processing process, hot air is led in, so that the temperature in the insulation cavity is improved, the damage effect of the pulse electric field to cytomembranes is effectively improved, the processing efficiency is improved, and the processing efficiency is improved.

High voltage pulse electric field processing chamber for garden stuff osmotic dehydration pretreatment

HighlightsThe impact sensors protected by shells and integrated with process circuits were proposed.Simulations and collision tests were performed to optimize the structure of the sensor.Accessories that can improve sensors’ detection accuracy were proposed.Multi-grain impact tests in a laboratory showed the RMSEs of two sensors were less than 1.67%.Abstract. Impact sensors are widely used to detect grain loss in harvesters, and the impact sensors with array structure polyvinylidene fluoride (PVDF) films have been proven to significantly increase the detection efficiency. However, uneven sensitivity and clutters from non-impacted sensitive units seriously affect the detection accuracy. This article proposes a protective shell for the impact sensors with array structure PVDF films. To improve the performance of this kind of sensor, we optimized the structure through finite element simulations and particle impact tests. The vibration modes under three pasting methods of sensitive units were analyzed. The relationship between the hardness of the elastic layer and response performances was investigated. To suppress the clutters, a method of splitting the elastic layer was proposed. Then, we manufactured two optimized impact sensors with one layer and two crossed layers of PVDF films and tested their performances. The results demonstrated that the sensitivities of the gaps between the PVDF films are poor. But when excluding the gaps’ data, the two sensors can meet the detection requirement. Accessories were proposed based on that characteristic to prevent particles from colliding with the gaps. After assembling the accessory, multi-grain impact tests showed that the root-mean-square errors (RMSEs) of the impact sensors with one layer and two crossed layers of PVDF films were 1.67% and 1.63%, respectively. Keywords: Grain loss detection, Particle impact test, Protective shell, Sensor accessory, Structure optimization.

Optimum Design of Impact Sensors With Array Structure Polyvinylidene Fluoride (PVDF) Films

The invention discloses a high-voltage pulse electric field processing chamber for fruit-vegetable permeation dehydration preprocessing. A bottom support supports a metal outer shell. A first filtering cloth and a second filtering cloth are fixedly arranged on the upper portion and the lower portion of an insulation cavity in the metal outer shell respectively through supports. A grounding electrode is fixedly embedded into the insulation cavity and is placed below the first filtering cloth. A plurality of tracks are symmetrically arranged above and below the two sides of the insulation cavity below the grounding electrode respectively. A high-voltage electrode is arranged on either of the tracks on the two sides of the insulation cavity. An air outlet pipe and an air inlet pipe are arranged on the top portion and the bottom portion of each of the metal outer shell and the insulation cavity. Two pipe openings are provided with thermocouples respectively. The high-voltage electrode and the grounding electrode are respectively connected with a high-voltage pulse generator. The high-voltage pulse electric field processing chamber can generate a pulse electric field in an air zone and directly process fruits and vegetables, procedures and cost are saved, during processing, hot air is injected, temperature in the insulation cavity is raised, damaging effect of the pulse electric field on cytomembranes is effectively promoted, processing effect is improved, and processing effect is improved.

Hongping Tian

Papers

A review of kinetic models for inactivating microorganisms and enzymes by pulsed electric field processing

A High-Voltage Solid-State Switch Based on Series Connection of IGBTs for PEF Applications

High voltage pulse electric field processing chamber for garden stuff osmotic dehydration pretreatment

Optimum Design of Impact Sensors With Array Structure Polyvinylidene Fluoride (PVDF) Films

High-voltage pulse electric field processing chamber for fruit-vegetable permeation dehydration preprocessing