Nonthermal pasteurization of onion juice by continuous UV‐C reactor

Abstract

The objective of this study is to investigate the continuous pasteurization of onion (Allium cepa L.) juice by ultraviolet (UV‐C) irradiation by a designed coiled‐tube type UV‐C reactor. System is composed of four vertical low‐pressure mercury lamps (20 W/lamp, 254 nm) coiled using a PTFE tube. A secondary eddy flow effect was achieved with a Dean number of 0.073. The Escherichia coli K‐12 count in onion juice was reduced by 4.83 log after exposure to UV‐C light for 8.13 min at an estimated UV‐C dosage of 38.1 J/mL with the flow rate of 1.26 L/min. After UV‐C treatment, the total color change (ΔE) of the onion juice was recorded as 1.15 which can be referred as slightly noticeable. Total aerobic mesophilic count of UV‐C irradiated samples was below acceptable limits after 6 weeks of storage. Meat marination in UV‐C‐treated onion juice reduced the hardness of meat by 78%. Practical applications Currently, many of the large‐scale processed meat producers prefer to marinate the meat directly in the onion juice or in a sauce formulation including onion juice. Therefore, they are the major end‐users of this product. In addition, onion juice has a large potential to be used by the catering industry providing food service for relatively large number of people. If the storage space for onions, the preparation, and service time for the meals are taken into consideration, catering services may highly benefit from the pasteurized onion juice products. Conventional heat treatment is the most common method to extend shelf‐life of vegetable juices. The results of this study indicated that continuous UV‐C irradiation can successfully be used to pasteurize onion juice. The outcomes will also serve the basis to technical knowledge for designing the pilot‐scale production of onion juice processed by nonthermal treatments.

A review on the application of UV‐C treatment on food and food surfaces: association with food microbiology, predictive microbiology and quantitative microbial risk assessment

“…E. coli was reduced by 4.83 log CFU/mL after exposure to UV‐C light for 8.13 min and a dose of 38.1 J/mL. The total mesophilic bacteria count did not exceed 4 log CFU/mL after 6 weeks of storage, and the product treated by radiation showed technological advantages compared to the product treated by conventional pasteurisation, such as less colour change and greater efficiency in meat tenderisation (Demir & Oral, 2018).…”

UV Processing and Storage of Liquid and Solid Foods: Quality, Microbial, Enzymatic, Nutritional, Organoleptic, Composition and Properties Effects

“…The majority of the authors did not observe any significant change in the pH, acidity and TSS content of UV treated foods during storage (Kaya et al, 2015;La Cava and Sgroppo, 2015;Chia et al, 2012). On the other hand, the changes in the pH, acidity and TSS content of the foods observed in some studies have been associated with microbial spoilage (Demir and Oral, 2018;Mansor et al, 2017). Turbidity and UV absorbance of the liquid foods, critical factors for UV processing, are closely related to the growth of microorganisms during storage period and also associated with the color degradation and darkening of samples (Chia et al, 2012;Tandon et al, 2003;Kaya et al, 2015;Unluturk and Atilgan, 2015).…”

Effect of ultrasonication and vacuum impregnation pretreatments on the quality of beef marinated in onion juice a natural meat tenderizer

“…Onions (Allium cepa L.) harvested in winter 2019 were purchased from the wholesale market in Osmaniye, Turkey. Mature, yellow and undamaged onions were selected and stored at þ4 C. The onion juice production method was modified from Demir and Oral (2018). For extraction of onion juice, a home-type juice extractor (J700, Braun, Kronberg, Germany, 1000 W) was used.…”