Application of MAP and ethylene–vinyl alcohol copolymer (EVOH) to extend the shelf-life of green and white asparagus (Asparagus officinalis L.) spears

Abstract

In this study, ethylene vinyl alcohol copolymer (EVOH) and polypropylene/polyethylene (PP/PE) films combined with MAP packaging were developed to enhance the shelf-life of green and white asparagus spears. The scope of the research included measurements of weight loss, pH, acidity, color, texture, and sensory analysis as indicators of green and white asparagus spear quality for up to 17 days of storage at 2 and 10 °C. The application of modified atmosphere packaging combined with EVOH-based packaging material and refrigeration at 2 °C promoted a reduction in asparagus weight loss, preventing changes in color and texture as well as sensory quality, thereby extending the shelf-life of the asparagus. According to the obtained results, it was possible to maintain good quality of green and white asparagus for up to 17 and 10 days, respectively, when packed in MAP using EVOH-based packaging stored at 2 °C. Asparagus stored in packaging with PP/PE film showed lower quality during storage at 2 and 10 °C. These results suggest that EVOH films are potential candidates for advanced packaging materials for the asparagus packaging application.

Sustainable Postharvest Treatments for Prolonging Asparagus (Asparagus officinalis L.) Shelf Life by Minimizing the Development of Physiological Disorders

“…The efficiency of vacuum packaging to maintain green asparagus postharvest quality can be improved when combined with cold water (0 °C) postharvest treatment for 60 min . MAP also has some disadvantages, such as the potential growth of some anaerobic bacteria at low O 2 levels (<1%) that result in the development of off-odor and quality deterioration, the high cost of gas packaging equipment, and the relationship between MAP and storage temperature, since storage temperature may affect the gas composition in the package and, hence, produce quality. ,, In conclusion, the higher CO 2 and lower O 2 levels during MAP may extend asparagus postharvest quality by (i) reducing respiration rates, (ii) inhibiting the synthesis of enzymes involved in lignification (i.e., PAL, POD), hence preventing toughening, (iii) inhibiting anthocyanin synthesis and chlorophyll catabolism, hence maintaining white and green asparagus color, respectively, and (iv) enhancing the synthesis of antioxidant enzymes (i.e., superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)), hence delaying asparagus senescence due to oxidative damage. ,,,, …”

“…noted a significant increase in the total amount of phenolic monomers and ferulate di- and trimers in white asparagus during postharvest storage at different temperatures (i.e., 20 and 1 °C). It is important to note that both ferulic and p -coumaric acids are intermediates in the lignin biosynthetic pathway. , Several parameters are responsible for enhancing asparagus toughening, including variety, storage temperature, storage duration, and ethylene presence in the storage atmosphere. ,,, Studies have shown that postharvest toughening is faster in white asparagus than in green. , This might be due to the different kinetics of enzymes (i.e., PAL, POD, etc.) involved in the metabolism (i.e., lignification) of the different asparagus varieties. ,, Specifically, it has been noted that PAL activity is higher in white asparagus than in green .…”

“…The discoloration of white asparagus is associated with the development of yellow, red, and violet colors mainly in the spear tips and secondarily in the stem, as well as a glassy (glassiness) or brown (browning) color mainly in the lower and middle surface area of the spears (i.e., stem) and less frequently on the bracts (Figure ). ,, Several postharvest parameters may affect white asparagus discoloration, including light type, duration of exposure to light, variety, handling before storage (i.e., hydrocooling, injuries on asparagus spears), and storage conditions (i.e., temperature, atmosphere composition, duration). ,,,− The development of yellow, red, and violet colors in asparagus is due to the synthesis and accumulation of flavonols (for the yellow color) and anthocyanins (for the red and violet color) in the epidermal tissue. ,, PAL has been characterized as a key enzyme in anthocyanin synthesis since it catalyzes the conversion of phenylalanine into cinnamic acid, a precursor for the anthocyanin metabolic pathway. Additionally, other enzymes such as C4H, 4CL, CHS, CHI, F3H, F3′H, DFR, ANS, and 3GT are also responsible for anthocyanin synthesis in asparagus. , Future studies are encouraged to investigate the critical factors that trigger the activity of each enzyme and lead to the anthocyanin synthesis in asparagus.…”

“…The effects of various packaging systems have been tested on the maintenance of green and white asparagus postharvest quality (Table ). Several studies have examined the effects of passive or active modified atmosphere packaging (MAP) on asparagus quality maintenance individually or in combination with other treatments (i.e., CO 2 or short-term anoxia pretreatments, types of films). ,,, The efficiency of MAP to maintain asparagus quality is influenced by packaging film permeability and storage temperature, with temperatures between 2 and 5 °C to be more favorable. , Gantner et al noted that ethylene vinyl alcohol copolymer (EVOH) film combined with active MAP (5% CO 2 , 15% O 2 , and 80% N 2 ) extended green and white asparagus postharvest quality for up to 17 and 10 days, respectively, at 2 °C, by delaying toughening and discoloration. Li and Zhang noted that silicon gum film combined with active MAP (5% O 2 and 10% CO 2 ) maintained green asparagus quality (i.e., appearance, firmness, and odor) above the acceptable limits during 30 days of storage at 2 °C.…”

“…It is important to note that both ferulic and p-coumaric acids are intermediates in the lignin biosynthetic pathway. 30,35 Several parameters are responsible for enhancing asparagus toughening, including variety, storage temperature, storage duration, and ethylene presence in the storage atmosphere. 27,34,36,37 Studies have shown that postharvest toughening is faster in white asparagus than in green.…”