ABSTRACT. The present study aimed to investigate the effects of pre-storage for 24h and 48h and different modified atmosphere packaging-MAP treatments (using low-density polyethylene - LDPE) on the antioxidant compounds and the postharvest quality of ‘Douradão’ peaches under cold storage. The peaches were submitted to the following treatments: a control (no packaging or pre-storage) and pre-storage for 24h or 48h at 25ºC combined with passive MAP (LDPE 60 µm or 80 µm). After the application of the treatments, the fruits were stored at 0ºC for 30 days plus 3 days at 25ºC to simulate marketing conditions. The results showed that on the simulated marketing period, all the treatments (except for the control) reduced woolliness and internal browning. Furthermore, both pre-storage and LDPE MAP enhanced the polygalacturonase (PG) activity, the levels of phenolic compounds and the antioxidant capacity. Thus, these results suggest that the pre-storage associated with LDPE packaging increases the shelf life of peaches by up to 30 days under cold storage.

Resumen: La elaboración de hortalizas de IV Gama requiere de una etapa de desinfección que reduzca el crecimiento de microorganismosalterantes y patogénicos. En general, esta desinfección requiere de la adición de productos sanitizantes como el cloroo sus hipocloritos. Debido a que el cloro reacciona con otros compuestos orgánicos, dando lugar a la formación desubproductos halogenados perjudiciales para la salud como trihalometanos y cloraminas, las preocupaciones sobre latoxicidad de estos derivados han dado lugar al interés actual por utilizar productos alternativos y amigables con el medioambiente. El interés por estos nuevos desinfectantes no solo se debe a su capacidad de inactivación frente a una ampliagama de microorganismos patógenos y deteriorantes, sino también a su capacidad para mantener la calidad sensorial delproducto. Actualmente, existen diversas técnicas sostenibles y emergentes de desinfección que pueden reemplazar al cloro,proporcionando otros beneficios, como sucede con el ozono (O3), el agua electrolizada (AE), las radiaciones ionizantes o no,los antimicrobianos naturales, las bacteriocinas, los tratamientos térmicos, determinados agentes químicos como el ácidoperoxiacético (AP) y otros muchos. En el presente trabajo revisaremos la eficacia del O3, AE y AP. Todos ellos handemostrado su eficacia microbicida con efecto frente a bacterias patógenas presentes en hortalizas de IV Gama.

Summary: The elaboration of fresh-cut vegetables needs a disinfection step to reduce the growth of spoilage and pathogenic microorganisms.In general, this requires the addition of sanitizers such as chlorine or hypochlorites. However, due to the fact that chlorinereacts with other organic compounds, leading to the formation of halogenated by-products that are harmful to health, such astrihalomethanes and chloramines, concerns over the toxicity of these derivatives have led to the current interest of usingalternative and environmentally-friendlier products. The concern over these new sanitizers is not only due to their inactivationcapabilities against a wide range of pathogenic and spoilage microorganisms, but at the same time, over their ability to maintainthe sensory quality of the product. Currently, there are a number of sustainable and emerging disinfection techniques that canreplace chlorine, providing other benefits, such as ozone (O3), electrolyzed water (AE), ionizing or non-ionizing radiation,natural antimicrobials, bacteriocins, heat treatments, certain chemical agents as peroxyacetic acid and many others. In thispaper, we review the effectiveness of O3, AE and peroxyacetic acid. All of them have proven their microbicidal efficacy againstpathogenic bacteria in fresh-cut vegetables.

La industria de procesado mínimo en fresco manifiesta un creciente interés por las ensaladas tipo «baby» en base a brotes hortícolas como el Tatsoi. Estas hortalizas deben desinfectarse utilizando métodos químicos y/o físicos que permitan mantener bajos los niveles de microorganismos durante su vida útil. Actualmente, se estudian nuevos desinfectantes químicos, sustitutivos de los derivados del cloro, más respetuosos con el ambiente y la salud humana. En este trabajo se estudió la efectividad microbiológica del ácido ascórbico (AA) a 30 y 60 mg L-1 y dióxido de cloro (ClO2) a 7 y 10,5 mg L-1, utilizando como testigos hipoclorito de sodio (NaClO) a 150 mg L-1 y agua. El material vegetal se lavó mediante inmersión durante dos minutos en los desinfectantes, se enjuagó un minuto con agua a 5 ºC, se centrifugó y 30 g de brotes fueron envasados en tarrinas que se almacenaron a 5 ºC durante ocho días. Los recuentos más bajos de mesófilos (6,2 log ufc g-1), psicrótrofos (4,8 log ufc g-1) y enterobacterias (3,5 log ufc g-1) se lograron utilizando AA a 60 mg L-1. Las levaduras presentaron un crecimiento inferior a 3,4 log ufc g-1 al utilizar NaClO o ClO2 a 10,5 mg L-1. Por tanto, AA y ClO2, a las concentraciones de 60 mg L-1 y 10,5 mg L-1 respectivamente, se comportaron como buenos sustitutos del NaOCl, capaces de controlar el crecimiento microbiano y mantener la vida útil de brotes de Tatsoi a 5 ºC durante ocho días sin afectar la calidad sensorial del producto.

The fresh-cut industry shows a growing interest in fresh «baby» salads based on vegetable sprouts as Tatsoi. These vegetables should be disinfected using chemical and/or physical methods to maintain low microorganisms levels during their life. Nowadays, new chemical disinfectants substitutes to chlorine derivatives, more respectful of the environment and human health, are in study. In this work, the microbiological effectiveness of ascorbic acid (AA) at 30 and 60 mg L-1, chlorine dioxide (ClO2) at 7 and 10.5 mg L-1 were studied. As control sodium hypochlorite (NaClO) at 150 mg L-1 and water were used. The plant material was washed by immersion for two minutes in the disinfectant, rinsed with water one minute at 5 °C, centrifuged, and 30 g of sprouts were packed in trays that were stored at 5 °C for eight days. The lower counts of mesophilic (6.2 log cfu g-1), psychotrophics (4.8 log cfu g-1) and Enterobacteriaceae (3.5 log cfu g-1) were achieved using AA to 60 mg L-1. Yeasts had a lower growth than 3.4 log cfu g-1, using NaClO or ClO2 at 10.5 mg L-1. Therefore, AA and ClO2, at concentrations of 60 and 10.5 mg L-1, behaved as good substitutes for NaOCl, capable of controlling microbial growth and maintain the life of Tatsoi sprouts at 5 °C for eight days without affecting sensory quality of the product.