Abstract:The vast and ever-growing amount of agricultural and food wastes has become a major concern throughout the whole world. Therefore, strategies for their processing and value-added reuse are needed to enable a sustainable utilization of feedstocks and reduce the environmental burden. By-products of potato, tomato, cereals and olive arise in significant amounts in European countries and are consequently of high relevance. Due to their composition with various beneficial ingredients, the waste products can be valorized by different techniques leading to economic and environmental advantages. This paper focuses on the waste generation during industrial processing of potato, tomato, cereals and olives within the European Union and reviews state-of-the-art technologies for their valorization. Furthermore, current applications, future perspectives and challenges are discussed.

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The inactivation of orange juice peroxidase (POD) under high-intensity pulsed electric fields (HIPEF) was studied. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency and pulse width) were evaluated and compared with conventional heat pasteurization. Samples were exposed to electric field strengths from 5 to 35 kV cm −1 for up to 1500 µs using square wave pulses in mono-and bipolar mode. Effect of pulse frequency (50-450 Hz), pulse width (1-10 µs) and electric energy on POD inactivation by HIPEF were also studied. Temperature was always below 40 • C. POD was totally inactivated by HIPEF and the treatment was more effective than thermal processing in inactivating orange juice POD. The extent of POD inactivation depended on HIPEF processing parameters. Orange juice POD inhibition was greater when the electric field strength, the treatment time, the pulse frequency and the pulse width increased. Monopolar pulses were more effective than bipolar pulses. Orange juice POD activity decreased with electric energy density input. The Weibull distribution function adequately described orange juice POD inactivation as a function of the majority of HIPEF parameters. Moreover, reduction of POD activity related to the electric field strength could be well described by the Fermi model.

: Mechanical operations such as peeling and cutting during minimal processing involve enzymatic browning of fruit tissue. The objective of this work was to evaluate the individual and combined effects of N‐acetyl‐L‐cysteine, reduced glutathione, ascorbic acid, and 4‐hexylresorcinol to control pear browning. Browning of fresh‐cut pears was prevented by a minimum concentration of 0.75% N‐acetyl‐L‐cysteine up to 28 d at 4°C. Reduced glutathione treatments were also effective along the storage time although browning was observed after 21 d of storage with a dip of 0.75% reduced glutathione. However, ascorbic acid or 4‐hexylresorcinol treatments did not seem to completely prevent browning of pear wedges throughout the storage period. An enhanced antibrowning effect was observed when combining both N‐acetyl‐L‐cysteine and reduced glutathione, considering hue angle as color change index. Thus, hue angle reached maximum levels at 1.5% N‐acetyl‐L‐cysteine (NAC) or 1.5% glutathione (GSH) and 1% NAC with 1% GSH for 28 d. Besides, N‐acetyl‐L‐cysteine, reduced glutathione and 4‐hexylresorcinol completely inhibited polyphenol oxidase activity as well as browning inhibitors slightly reduced firmness of fresh‐cut pears.

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