Influence of respiratory quotient dynamic controlled atmosphere (DCA – RQ) and ethanol application on softening of Braeburn apples

Elevated CO2 in dynamic controlled atmosphere storage: Impact on anaerobic metabolism and overall quality of 'Maxi Gala' apples

BACKGROUND

The present study investigated the effects of high CO2 partial pressures (pCO2) in dynamic controlled atmosphere monitored by respiratory quotient (DCA-RQ 1.3) on the anaerobic metabolism compounds, physiological disorders and overall quality of 'Maxi Gala' apples after 9 months of storage (2.0 °C), plus 7 days of shelf life (20 °C). Two experiments were conducted over 2 years. In the first year, 'Maxi Gala' apples were stored under controlled atmosphere (CA - 1.2 kPa O2 + 2.0 kPa CO2), CA + 1-methylcyclopropene (1-MCP), DCA by chlorophyll fluorescence (DCA-CF + 1.2 kPa CO2) and DCA-RQ 1.3 with different pCO2 (0.4, 1.2, and 1.6). The same treatments were evaluated in the second year, with addition of DCA-RQ 1.3 + 2.0 kPa CO2.

RESULTS

'Maxi Gala' apple stored under DCA-RQ 1.3 + 0.4 kPa CO2 and DCA-CF maintained healthy fruit amount similar to DCA-RQ 1.3 + 1.2 and 1.6 kPa CO2, but with lower flesh firmness. DCA-RQ 1.3 with higher pCO2 (1.6 or 2.0) increases the production of ethyl acetate, but did not impact physiological disorders compared to DCA-CF. CA + 1-MCP maintained high flesh firmness, but reduced healthy fruit amount.

CONCLUSION

The present study has demonstrated that DCA-RQ 1.3 with 1.6 or 2.0 pCO2 can be adopted for 'Maxi Gala' apples storage, resulting in similar or better fruit quality than DCA-RQ 1.3 + 1.2 kPa CO2. Additionally, the adoption of high pCO2 in the DCA-RQ storage system can result in cost reductions related to CO2 adsorption. © 2024 Society of Chemical Industry.

Comparative Analysis of Aroma Emissions in 'Gala' Apples Stored in Ethanol- and Hexanal-Enriched Controlled Atmosphere

The objectives of this study were to investigate the effects of extended and constant ethanol and hexanal exposure on 'Gala' apples' production of aroma compounds after long-term CA storage. 'Gala' apples were stored in a CA under 2 kPa O2 and 98 kPa N2 at 1.0 ± 0.1 °C with a constant ethanol (CA-et) or hexanal (CA-he) concentration maintained at 50 µgL-1 throughout a six-month storage period. A total of 25 volatile compounds (VOCs) were identified. The odor activity value (OAV) results show that nine VOCs were key aroma compounds. Among them, hexyl acetate, 2-methylbutyl acetate, and 1-butanol were the highest. Hexanal increased the production of hexyl acetate, while ethanol increased the production of 2-methylbutyl acetate and ethyl 2-methylbutanoate. Both precursors promoted the production of 1-butanol after two months of storage and 1 day of shelf life. Overall, the impact of the precursors on aroma production was more pronounced after two months than after six months of storage. Different storage atmospheres significantly influenced VOC correlations, suggesting that ethanol and hexanal addition altered aroma biosynthesis pathways in the 'Gala' apples. For varieties like 'Gala' that rapidly lose their aroma during CA storage, CA-et and CA-he treatments may be beneficial for short-term storage, enhancing key aroma compounds and improving sensory quality.

Impact of different storage conditions with combined use of ethylene blocker on 'Shalimar' apple variety

This research investigates the impact of storage conditions on the quality and preservation of 'Shalimar' apples, a relatively new cultivar known for its resistance to apple scab and powdery mildew. The study explores the efficacy of different storage techniques such as regular atmosphere (RA), controlled atmosphere (CA), and dynamic controlled atmosphere with CO2 Monitoring (DCA-CD), as well as the integration of 1-methylcyclopropene (1-MCP) at different storage temperatures (1 °C and 3 °C). Various fruit quality parameters were monitored under different storage conditions, including firmness, titratable acidity, total soluble solids, background color, respiration, ethylene production, and volatile compounds. The results indicate that the controlled atmosphere (CA) at 1 °C emerges as an efficient method for long-term storage. However, it is noted that CA storage may impact the apple aroma, emphasizing the need for a balance between preservation and consumer acceptability. On the other hand, DCA-CD at variable temperatures (approximately 2.5 °C) offers a promising approach for maintaining fruit quality and a higher concentration of volatile compounds. Integrating 1-MCP enhances firmness, but its impact varies across storage conditions. Principal component analysis (PCA) provides insights into the relationships between storage conditions, fruit quality, and volatile compounds. This study contributes valuable insights into optimizing storage strategies for 'Shalimar' apples, addressing sustainability and quality preservation in apple production.

Reflections on food security and smart packaging

Estimating the number of COVID-19 cases in 2020 exacerbated the food contamination and food supply issues. These problems make consumers more concerned about food and the need to access accurate information on food quality. One of the main methods for preserving the quality of food commodities for export, storage, and finished products is food packaging itself. In the food industry, food packaging has a significant role in the food supply which acts as a barrier against unwanted substances and preserves the quality of the food. Meanwhile, packaging waste can also harm the environment; namely, it can become waste in waterways or become garbage that accumulates because it is nonrenewable and nonbiodegradable. The problem of contaminated food caused by product packaging is also severe. Therefore, to overcome these challenges of safety, environmental impact, and sustainability, the role of food packaging becomes very important and urgent. In this review, the authors will discuss in more detail about new technologies applied in the food industry related to packaging issues to advance the utilization of Smart Packaging and Active Packaging.

Recent advances in Penicillium expansum infection mechanisms and current methods in controlling P. expansum in postharvest apples

One of the most significant challenges associated with postharvest apple deterioration is the blue mold caused by Penicillium expansum, which leads to considerable economic losses to apple production industries. Apple fruits are susceptible to mold infection owing to their high nutrient and water content, and current physical control methods can delay but cannot completely inhibit P. expansum growth. Biological control methods present promising alternatives; however, they are not always cost effective and have application restrictions. P. expansum infection not only enhances disease pathogenicity, but also inhibits the expression of host-related defense genes. The implementation of new ways to investigate and control P. expansum are expected with the advent of omics technology. Advances in these techniques, together with molecular biology approaches such as targeted gene deletion and whole genome sequencing, will lead to a better understanding of the P. expansum infectious machinery. Here, we review the progress of research on the blue mold disease caused by P. expansum in apples, including physiological and molecular infection mechanisms, as well as various methods to control this common plant pathogen.

Methods of detection of β-galactosidase enzyme in living cells

The application of β-galactosidase enzyme ranges from industrial use as probiotics to medically important application such as cancer detection. The irregular activities of β-galactosidase enzyme are directly related to the development of cancers. Identifying the location and expression levels of enzymes in cancer cells have considerable importance in early-stage cancer diagnosis and monitoring the efficacy of therapies. Most importantly, the knowledge of the efficient method of detection of β-galactosidase enzyme will help in the early-stage treatment of the disease. In this review paper, we provide an overview of recent advances in the detection methods of β-galactosidase enzyme in the living cells, including the detection strategies, and approaches in human beings, plants, and microorganisms such as bacteria. Further, we emphasized on the challenges and opportunities in this rapidly developing field of development of different biomarkers and fluorescent probes based on β-galactosidase enzyme. We found that previously used chromo-fluorogenic methods have been mostly replaced by the new molecular probes, although they have certain drawbacks. Upon comparing the different methods, it was found that near-infrared fluorescent probes are dominating the other detection methods.

A ratiometric fluorescent probe for the detection of β-galactosidase and its application

Herein, a coumarin fluorescent probe (Probe 1) was developed for the ratiometric detection of β-galactosidase (β-gal) activity. The detection range was 0–0.1 U mL⁻¹ and 0.2–0.8 U mL⁻¹, and the limit of detection (LOD) was 0.0054 U mL⁻¹. Moreover, the luminous intensity of Probe 1 increased gradually with increase in β-gal activity. It could be observed under 254 nm UV irradiation by the naked eye. Furthermore, this method only required a small amount of sample (20 μL) and a short analytical time (30 min) for the detection of β-gal activity with a low LOD. Probe 1 was successfully used to detect β-gal activity in real fruit samples, and can be applied to the quantitative and qualitative detection of β-gal activity.

A ratiometric fluorescent probe was successfully used as a tool to determine β-galactosidase activity in fruits.

Ethylene scavengers for the preservation of fruits and vegetables: A review

The phytohormone ethylene is the main cause of postharvest spoilage of fruit and vegetables (F&V). To address the global challenge of reducing postharvest losses of F&V, effective management of ethylene is of great importance. This review summarizes the various ethylene scavengers/inhibitors and emerging technologies recently developed for the effective removal of ethylene released, paying particular attention to the ethylene scavenger/inhibitors containing catalysts to promote the in-situ oxidation of ethylene without inducing further pollution. Packing ethylene scavengers, such as zeolite, titanium dioxide and transition metals, in a small sachet has been practically used and widely reported. However, incorporating ethylene scavenger into food packaging materials or films along with the in-situ oxidation of ethylene has been rarely reviewed. The current review fills up this gap, covering the latest research progress on ethylene scavengers/inhibitors and discussion on the mechanisms of ethylene elimination and oxidation associated with F&V packaging.

Inhibition of fruit softening by cold plasma treatments: affecting factors and applications

Softening is a common phenomenon of texture changes associated with plant cell walls, inducing a decrease in the quality of fruit. Inhibiting the softening is effective to extend the shelf life of fruit. Cold plasma (CP), as a novel nonthermal technology, has been applied to keep the freshness of the fruit. This review centers on applying cold plasma treatments to the inhibition of fruit softening. Different pathways for inhibiting fruit softening by CP treatments, including maintenance of fruit firmness, reduction in the activities of enzymes, inactivation of fungal pathogens and lowering of respiration rates, are discussed. The biochemistry of fruit softening and the fundamental of cold plasma are also presented. In general, among all postharvest technologies, cold plasma is a promising method with many advantages, showing great potential in maintaining the quality and inhibiting the softening of the fruit. Future work should focus on process optimization to achieve better results in maintaining fruit freshness, and commercial applications of cold plasma technology should also be explored.