Postharvest heat treatments to inhibit Penicillium digitatum growth and maintain quality of Mandarin (Citrus reticulata blanco)

Use of fungicides is a common practice as a postharvest treatment to control fruit decay. Nowadays, environment-friendly technologies, such as heat treatments, are viable replacements. This study evaluated the effects of post-harvest heat treatments (traditional and microwave-assisted) on mandarins intentionally inoculated with Penicillium digitatum. For the studied heat treatments, the target temperature was 50C, which was held for 2.5 min. After heating, mandarins were cooled and stored at 25C for 13 days. MW treatments effectively prevented mold growth during storage, while HW only delayed it. Control mandarins (without treatment) showed the highest significant weight loss. Neither thermal treatment nor storage affected fruit juice pH (p \u3e 0.05). Treated mandarins had a significantly lower vitamin C content than control fruits throughout storage, and all mandarins lost firmness by the 13th day (p \u3c 0.05). Control and MW-treated mandarins had lower citric acid content; however, they retained color, total soluble solids (TSS) and had a higher maturity index. While HW mandarins did not have changes in citric acid content, they had higher TSS, and lower maturity index. MW-assisted treatments were effective at inactivating molds and helped retain some nutritional and physical-chemical characteristics of mandarins. However, juice of MW-treated mandarins was not preferred by judges in the sensory tests, the juice was rated lower than that obtained from the other treatment. Postharvest heat treatments may constitute a helpful application to control mandarin’ fungal decay

Antimicrobial Activity and Physicochemical Characterization of Oregano, Thyme and Clove Leave Essential Oils, Nonencapsulated and Nanoencapsulated, Using Emulsification

Background and objective: Functional properties of essential oils are attributed to their components, many of which exhibit antimicrobial activity against pathogenic and spoilage microorganisms in a wide variety of foods. However, essential oils are unstable compounds; therefore, they can be encapsulated for a better protection and increase of functionality. In this work, antimicrobial activities of oregano, thyme and clove leave essential oils (non-encapsulated and nanoencapsulated) were assessed against Escherichia coli ATCC 29922, Salmonella typhimurium ATCC 14028 and Staphylococcus aureus ATCC 25923 using emulsification.Material and methods: The essential oils were characterized based on their physicochemical properties. Nanoemulsions were prepared, using 5% (w w-1) of essential oils, and then characterized based on their physical properties, stability and encapsulation efficiency. The microdilution antimicrobial assay was carried out to assess minimum inhibitory concentration and minimum bactericidal concentration of the essential oils and their nanoemulsions. Data from physical properties of the essential oils and physical properties, stability and encapsulation efficiency of the nanoemulsions were statistically analyzed.Results and conclusion: Antimicrobial activity of the essential oils showed decreases in minimum inhibitory concentration by 27-60% for the nanoencapsulated oils, compared to nonencapsulated oils. Nanoencapsulated and nonencapsulated oregano essential oils exhibited the lowest minimum inhibitory concentration and minimum bactericidal concentration values. Based on the results, nanoencapslulated essential oils may further be used in various foods to avoid microbial contaminations.Conflict of interest: The authors declare no conflict of interest

Postharvest heat treatments to inhibit Penicillium digitatum growth and maintain quality of Mandarin (Citrus reticulata blanco)

Use of fungicides is a common practice as a postharvest treatment to control fruit decay. Nowadays, environment-friendly technologies, such as heat treatments, are viable replacements. This study evaluated the effects of post-harvest heat treatments (traditional and microwave-assisted) on mandarins intentionally inoculated with Penicillium digitatum. For the studied heat treatments, the target temperature was 50C, which was held for 2.5 min. After heating, mandarins were cooled and stored at 25C for 13 days. MW treatments effectively prevented mold growth during storage, while HW only delayed it. Control mandarins (without treatment) showed the highest significant weight loss. Neither thermal treatment nor storage affected fruit juice pH (p \u3e 0.05). Treated mandarins had a significantly lower vitamin C content than control fruits throughout storage, and all mandarins lost firmness by the 13th day (p \u3c 0.05). Control and MW-treated mandarins had lower citric acid content; however, they retained color, total soluble solids (TSS) and had a higher maturity index. While HW mandarins did not have changes in citric acid content, they had higher TSS, and lower maturity index. MW-assisted treatments were effective at inactivating molds and helped retain some nutritional and physical-chemical characteristics of mandarins. However, juice of MW-treated mandarins was not preferred by judges in the sensory tests, the juice was rated lower than that obtained from the other treatment. Postharvest heat treatments may constitute a helpful application to control mandarin’ fungal decay

Naturally occurring compounds - Plant sources

Food market trends are changing, consumers more frequently demand high-quality foods with fresh-like attributes (Alzamora et al., 2016; Gould, 1995a, 1995b, 1996), and consequently less extreme treatments and/or additives are being required. To satisfy consumer demands, adjustments or reductions in conventionally used preservation techniques must be accomplished. Gould (2002) identified some food characteristics that must be attained in response to consumer demands; most of them occur within the minimal processing concept (Berdejo et al., 2019). To satisfy market requirements, the safety and quality of foods have to be based on substantial improvements in traditional preservation methods (Aguilar-González et al., 2015; Lorenzo-Leal et al., 2019a, 2019b; Mani-López et al., 2018, Reyes-Jurado et al., 2019b). Safe food may have different meanings to different people involved in the food chain; consumers for instance, relate a risk-free food as a safe one, and associate increased risk with the increased use of added substances such as antimicrobials, synthetic additives, and higher levels of sodium or fat, among others (Reyes-Jurado et al., 2019b). Scientists, public health officers, and international organizations define a safe food as one that provides maximum nutrition and quality while posing a minimal hazard to public health, and expect any risks that are present to be minimal (Shank and Carson, 1992).Fil: Lopez Malo, Aurelio. No especifíca;Fil: Alzamora, Stella Maris. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Quimicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Quimicos.; ArgentinaFil: Paris, María J.. No especifíca;Fil: Lastra Vargas, Leonor. No especifíca;Fil: Coronel, María Bernarda. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Quimicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Quimicos.; ArgentinaFil: Gómez, Paula Luisina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Quimicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Quimicos.; ArgentinaFil: Palou, Enrique. No especifíca