Presented work evaluated how quality of catfish fillets is affected by treatments using lactic acid or lysozyme in combination with chlorine. Fish fillets without skin were consecutively immersed and washed in 100 ppm chlorine solution and sprayed with 2.5% lactic acid or 0.5% lysozyme solution. Control samples were only washed with water at the same time. Samples were stored at 2 °C for 10 days in vacuum packaging. Parameters of pH, firmness, surface color and microbial cell counts (cfu/g) were measured on the 1st, 4th, 7th and 10th days. Especially the latter had high importance from the point of view of food safety. Catfish fillets shown decreased survival of microorganisms as a result of treatment. Lysozyme and lactic acid achieved 1.8 and 2.4 log cfu/g reduction, respectively. Lower cell counts were observed for all treated samples compared to control during 10 days. Chlorine in combination with lactic acid achieved the best efficiency. The results are promising and suggest that combined treatment is able to improve safety by controlling microorganisms on fish fillets during cold storage.
Authors:Mai Sao Dam, Vuong Duc Nguyen, Tamás Zsom, Lien Le Phuong Nguyen, and Géza Hitka
The effect of storage temperature and ozone treatment on the post-harvest quality of cucumber and tomato was investigated. Cucumber and tomato were stored together with or without gaseous ozone treatment at 20 °C and 14 °C for 16 days. Firmness, color, weight loss, DA index and decay percentage of samples were evaluated during storage period. The results showed that the combination of ozone treatment and cold storage could maintain the quality of these horticultural products and decreased the decay incidence. Additionally, this combination also reduced the weight loss of samples during storage. Furthermore, ozone treatment maintained the green skin color of cucumber. No sign of chilling injury occurred during storage at 14 °C. Commodities stored with approximately 0.1 ppm gaseous ozone at 14 °C retained the firmness compared to other treatments until the end of the experiment. This study suggests a promising use of gaseous ozone treatment in storage chamber where ethylene-producing and ethylene-sensitive vegetables are stored together.
Authors:Mai Sao Dam, Lien Le Phuong Nguyen, Tamás Zsom, Géza Hitka, Ildikó Csilla Zeke, and László Friedrich
The aim of this work was to evaluate the effect of packaging perforation on quality of carrot slices during cold storage at 5 °C. Polyethylene bags with different number of perforations (3, 4, and 6) were used in this experiment. Headspace oxygen concentration, respiration, weight loss, surface color, firmness, pH, and soluble solid content were examined throughout storage. It was observed, that all the investigated packaging were effective in maintaining the quality of carrot slices compared to the control. There was no symptom of decay until 12 days. In addition, pH, soluble solid content, and firmness showed nonsignificant change. Moreover, weight loss of packed carrot slices was below 2% after 12 days of storage. Packed carrot had better appearance at the end of experiment (12 days) than that of control.
Authors:Mai Sao Dam, Xuan Thi To, Quoc Tan Pham Le, Lien Le Phuong Nguyen, László Friedrich, Géza Hitka, Tamás Zsom, Tien Cam Thi Nguyen, Chuong Quang Huynh, My Diem Thi Tran, and Vuong Duc Nguyen
The aim of this study was to evaluate the effect of edible coating on hydroponic strawberry during storage. Strawberries were coated with either 1% or 1.5% chitosan (CS) or with solution containing 1.5% chitosan and 0.5% calcium gluconate (CaGlu). After treatment, samples were stored at 10 °C, RH 90% for 10 days. The weight loss, soluble solid content, firmness, surface color, pH, and percentage of decay were evaluated each day during the experiment. It was observed that coating extended the postharvest life of hydroponic strawberry compared to control. Fungal growth occurred on control group at the 5th day and fruit treated with 1% CS at the 8th day of the storage period, whereas no visible sign was detected for other treatments. Soluble solid content and pH showed only minor change for all samples. Weight loss of coated fruit was below 6% after 10 days of storage, whereas the weight loss of control samples was around 10% at the end of measurement. Moreover, coating could maintain the firmness of strawberry compared to the control. The combination of chitosan and calcium gluconate showed the potential for prolonging the storage period of hydroponic strawberry till 10 days without decay, whereas the control sample had more than 60% of rotted fruit.
Authors:Lien Phuong Le Nguyen, Vivien Horváth, Mai Sao Dam, Géza Hitka, Tamás Zsom, and Zoltán Kókai
This work was aimed to investigate the effect of 1-methylcyclopropene (1-MCP), ethylene absorber (EA), ozone alone or in combination on melon quality during storage. Ethylene production, respiration rates, acoustic firmness, surface color, chilling injury, and disease severity of melon were determined. 1-MCP treated fruits and non 1-MCP treated fruits were stored with sachets of ethylene absorber containing KMnO4 or ozone at 0.1 ppm/h during 10 days at 5 °C and subsequent 4 days at 20 °C. Melons treated with 1-MCP were firmer than the rest of the samples during storage. In addition, 1-MCP reduced the yellowing of melon rind compared to other treatments. The combination of 1-MCP and EA did not offer any additional effect in comparison with 1-MCP alone. There was no significant difference between fruits stored with ethylene absorber, ozone and control samples. Ozone treatment during cold storage decreased disease severity, however, fruits exposed to ozone had more serious decay throughout storage at 20 °C, probably due to the unclean air in the chamber.
Authors:Tamás Zsom, Edina Strohmayer, Lien Phuong Le Nguyen, Géza Hitka, and Viktória Zsom-Muha
Banana is a really chilling injury sensitive product. Its sensitivity to cold temperatures generates serious practical, economical and commercial problems. Chilling injury related physiological responses of Cavendish type green banana samples stored at 2.5, 5, 10 °C and near optimal (15 °C) cold storage temperature were investigated by nondestructive optical methods (surface color and chlorophyll fluorescence measurement, DA-index® evaluation) and by the determination of the physiological reactions (respiration, ethylene production, symptom manifestation) during cold storage and the 8-day long subsequent shelf-life. The positive effects of low temperature storage were proven on mass loss, respiration and ethylene production. In case of bananas stored at 2.5–10 °C, the chilling injury related changes in chlorophyll content related DA-index®, IR-values; Fm and Fv chlorophyll fluorescence values, the L*, a*, b*, C* and hue angle color characteristics suggested clearly from day 3 the onset of chilling injury several days before the visible signs of chilling injury appeared.
Authors:L.L.P. Nguyen, G. Szabó, T. Zsom, and G. Hitka
This work aimed to evaluate the effect of ethylene treatment on ripening of 1-MCP treated pear after 6 months of cold storage. Pear treated with gaseous 1-MCP at 625–650 ppb for 24 h at 0 °C was stored at 0 °C for 6 months with normal air, and treated groups were exposed to 100 ppm ethylene at 20 °C for 24 h. After that, samples were kept at 0, 10, and 15 °C for 2 weeks. Stiffness, chlorophyll fluorescence, ethylene and CO2 production of fruit were investigated during 2 weeks. Application of ethylene resumed the ripening of pear after long term storage. The results showed that fruit treated with ethylene achieved more homogeneous surface colour in comparison with non ethylene treated pears. In addition, the ethylene and carbon dioxide production of ethylene treated pears had higher values than that of control. The ethylene treatment could accelerate the softening of pear. Temperature also has significant effect on ripening during storage. This study found that ethylene treatment could accelerate the normal ripening of 1-MCP treated pears.
Authors:Tamás Zsom, Petra Polgári, Lien Phuong Le Nguyen, Géza Hitka, and Viktória Zsom-Muha
Broccoli's high perishability and its sensitivity to negative quality changes (i.e., mass loss, ethylene induced degreening, abscission of leaves, and florets) generates quality problems during postharvest. Freshly harvested samples were stored at 5 and 21 °C after separately treated for 24 h with 625 ppb 1-methyl-cyclopropene (1-MCP), 24 h with 2 ppm ethylene and 1-MCP followed by ethylene. Quality maintenance effectivity of 1-MCP was investigated during cold and room storage by non-destructive optical methods (chlorophyll fluorescence and DA-index®) and by the evaluation of the visual physiological symptoms. The highly positive effects of 1-MCP treatment combined with cold storage were obviously proven on quality maintenance providing better retention of initial quality related to the initial mature green stage as chlorophyll content related DA-index®; Fm, Fv, Fv/Fm, and Fm/F0 chlorophyll fluorescence values. From the practical point of view, the rapid, and easy-to-use Sintéleia FRM01-F Vis/NIR DA-meter® could be applied relatively easy for the quality measurement of broccoli. The reproducibility of quality determination could be increased by the enhanced number of measuring points or using computer aided imaging methods (i.e., chlorophyll fluorescence imaging, machine vision system) providing global and more reliable information about quality changes.
Authors:Viktória Zsom-Muha, Lien Le Phuong Nguyen, László Baranyai, Géza Hitka, Zsuzsanna Horváth-Mezőfi, Gergő Szabó, and Tamás Zsom
Among improper harvest and/or postharvest storage conditions, the effect of direct sunlight plays an important role in quality degradation of potato resulting in the development of green surface color based on chlorophyll formation associated with the formation of poisonous chemicals – glycoalcaloids – known as α-chaconine and α-solanine. Yellow skinned and fleshed potatoes with or without visible initial marks of green surface color were stored at normal room temperature under direct natural (sun)light conditions for almost two months. The aim of this study was the preliminary investigation of the sunlight induced formation of chlorophyll related compounds in potato indirectly by the detection of chlorophyll development. This attempt was based on nondestructive determination of chlorophyll related spectral and fluorescence indices for both sunlight exposed and unexposed potato sides. For both potato groups the chlorophyll content related DA-index® and chlorophyll fluorescence characteristics (F0, Fm, Fv and Fv/Fm) increased during the storage period representing chlorophyll formation. In the case of Fm, Fv and Fv/Fm values, the yellow samples reached the values of the initial spotted green samples by the 7th–9th days. From this time, the chlorophyll fluorescence values changed only minimally. After storage day 34, in the case of both at day 0 yellow and green spotted potatoes, the sunny side's F0 value was lower than that of shaded side. Close relationship was found between the results of Walz monitoring-PAM (Pulse Amplitude-Modulated) chlorophyll fluorometer and the PSI (Photon Systems Instruments) chlorophyll fluorescence imaging device (e.g. Fv R2 = 0.7226). According to our preliminary results, the Vis/NIR DA-meter®, the monitoring-PAM and the chlorophyll fluorescence imaging fluorometers were found to be suitable nondestructive devices for further investigations concerning the postharvest chlorophyll formation based greening phenomena, which is associated with solanine development in potato.
Authors:Tamás Zsom, Viktória Zsom-Muha, Lien Phuong Le Nguyen, Dávid Nagy, Géza Hitka, Petra Polgári, and László Baranyai
Application of cold storage temperatures below optimum induces a high risk and threat of chilling injury (CI) in the case of sensitive commodities. Sweet pepper belongs to this group of vegetables, so our main objective was to investigate and monitor the effect of non-optimal temperatures (2.5 and 5 °C) induced stress (chilling injury) on kápia type sweet pepper (Capsicum annuum L.) during its postharvest storage by nondestructive quality measuring methods. Fresh, semi-matured (reddish-green colored) samples of ‘Kapitány F1’ cultivar were stored at 2.5, 5 and 10 °C for 7 d followed by 7 d shelf-life. Nondestructive texture measurements were carried out by a purpose built tabletop acoustic stiffness device. Surface color and chlorophyll content related quality indices were evaluated by a chroma meter, a DA-meter® and a chlorophyll fluorescence imaging system. High resolution digital pictures were captured and analyzed for possible CI defects by means of surface color values (normalized RGB, hue and saturation). According to our results, the evaluated quality indices (DA-index®, acoustic stiffness coefficient, surface color parameters; F0, Fm, Fv and Fv/Fm chlorophyll fluorescence parameters) clearly represented the temperature dependent quality changes during low temperature storage, subsequently followed by ambient shelf-life. Samples stored under and at 5 °C showed the chilling temperature stressed symptoms of delayed and partly retarded postharvest ripening, even under simulated shelf-life conditions, but without the onset and manifestation of the characteristic visible symptoms of chilling injury. This may raise doubts and suggest possible future research areas regarding the role of non-optimal cold storage temperatures induced stress, the effect of chilling injury contributing factors and consequences.