Modified atmosphere packaging of precooked vegetables: effect on physicochemical properties and sensory quality

Design of equilibrium modified atmosphere packaging for postharvest cabbages preservation based on introducing available active sites into film materials as gas transport channels

This work aims to explore an available avenue to design an equilibrium modified atmosphere packaging (EMAP) by the modification of gas permeability of material. In this work, the introduction of available active sites endowed materials with adjustable gas permeability properties. With varying concentrations of the resulting materials with various gas permeability, the CO2 and O2 gas permeability of the blending films were modified at the range of 3.92 ∼ 17.84 barrier and 0.65 ∼ 3.46 barrier, respectively. On this basis, the films were used as EMAP to preserve postharvest cabbages. The results indicated that each EMAP achieved an equilibrium atmosphere containing 6.8 % ∼ 3.8 % CO2 and 2.1 % ∼ 5.2 % O2 within 15 h and maintained it continuously. In these atmosphere, the respiratory rate of the preserved cabbages was significantly inhibited, thereby delaying the deterioration of their storage quality. As the results, sensory scores of the preserved samples were maximally maintained. Declines of color indexes and texture indexes were obviously inhibited. Chemical variations in chlorophyll content, total phenolics content, total flavonoids content, ascorbic acid and nitrite content were significantly suppressed. The overall findings revealed that this method is suitable and promising to develop EMAP for the postharvest vegetables.

Coupling dynamics of respiration, gas exchange, and Pseudomonas fluorescens growth on fresh-cut cucumber (Cucumis sativus L.) in passive modified atmosphere packing

This study established microbial growth models for fresh-cut cucumber packaged with different O2 transmission rate (OTR) films. Biaxially oriented polyamide/low-density polyethylene (BOPA/LDPE) film (Ⅰ: OTR5, Ⅳ: OTR48) and polyethylene (PE) film (Ⅱ: OTR2058, Ⅲ: OTR3875) were used to construct a passive modified atmosphere packaging (MAP). Mathematic models have been established to account for dynamic variations in the O2/CO2 concentration and their impacts on Pseudomonas fluorescens growth. The coupling models included: 1) respiration models of cucumber and P. fluorescens based on Michaëlis-Menten equation, 2) coupling gas exchange models based on Fick's law that contained models of P. fluorescens growth and respiration, 3) coupling microbial growth models contained respiration and gas exchange models. Coupling model with Baranyi function successfully fitted variations of O2/CO2 concentration and P. fluorescens growth in the two packaging. In addition, quality properties of packed fresh-cut cucumber were determined. The film Ⅳ (OTR48) as a high barrier film showed the highest inhibition of P. fluorescens growth, adequately retained its colour, firmness and total soluble solid (TSS) concentration in contrast to the PE films packaging. The constructed coupling models can be utilized for assessing the shelf life and microbial growth of fresh-cut vegetables with spoilage dominated by pseudomonads.

A combination of modified atmosphere packaging and two chemical disinfectants: Effects on microbial, sensory, and physicochemical properties of raw ready-to-eat leek

In the present study, the effect of modified atmosphere packaging (MAP) on microbial (total aerobic count, yeasts and molds, Enterobacteriaceae, psychrotrophic bacteria, and lactic acid bacteria), physicochemical (pH, moisture content, and color), and sensory properties of raw ready-to-eat leek was investigated after disinfection using Percidin-Nanosil disinfectants. There were six different treatments, of which four samples were packaged as MAP (T₁ to T₄) and two samples were packaged as non-MAP (T₅ and T₆). The highest and the lowest reduction in the number of microorganisms after disinfection was observed in psychrotrophic bacteria and total aerobic count, respectively. The count of microbial variables in T₂ sample (87% N₂, 3% CO₂, and 10% O₂) was lower than in other treatments. No significant difference was observed in the physcochemical properties (moisture and pH) of treated samples except for the color of T₆ sample (cling film) compared to other treatments (p < .05). It is noteworthy that the panelists did not recognize differences among T₁, T₂, and T₅ samples. However, T₂ treatment was effective in maintaining microbial, physicochemical, and sensory properties of leek compared to the other treatments. Also, T₆ sample showed the lowest quality in all parameters. Disinfection combined with MAP was able to maintain the physicochemical, microbial, and sensory properties of raw ready-to-eat leek during storage.

Evaluation of Quality, Antioxidant Capacity, and Digestibility of Chickpea (Cicer arietinum L. cv Blanoro) Stored under N2 and CO2 Atmospheres

The aim of this work was to monitor the quality, antioxidant capacity and digestibility of chickpea exposed to different modified atmospheres. Chickpea quality (proximal analysis, color, texture, and water absorption) and the antioxidant capacity of free, conjugated, and bound phenol fractions obtained from raw and cooked chickpea, were determined. Cooked chickpea was exposed to N₂ and CO₂ atmospheres for 0, 25, and 50 days, and the antioxidant capacity was analyzed by DPPH (2,2'-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis-[3ethylbenzothiazoline-6-sulfonic acid]), and total phenols. After in vitro digestion, the antioxidant capacity was measured by DPPH, ABTS, FRAP (ferric reducing antioxidant power), and AAPH (2,2'-Azobis [2-methylpropionamidine]). Additionally, quantification of total phenols, and UPLC-MS profile were determined. The results indicated that this grain contain high quality and high protein (18.38%). Bound phenolic compounds showed the highest amount (105.6 mg GAE/100 g) and the highest antioxidant capacity in all techniques. Cooked chickpeas maintained their quality and antioxidant capacity during 50 days of storage at 4 and -20 °C under a nitrogen atmosphere. Free and conjugated phenolic compounds could be hydrolyzed by digestive enzymes, increasing their bioaccessibility and their antioxidant capacity during each step of digestion. The majority compound in all samples was enterodiol, prevailing the flavonoid type in the rest of the identified compounds. Chickpea contains biological interest compounds with antioxidant potential suggesting that this legume can be exploited for various technologies.

The combined impact of calcium lactate with cysteine pretreatment and perforation-mediated modified atmosphere packaging on quality preservation of fresh-cut 'Romaine' lettuce

The effect of perforation-mediated modified atmosphere packaging (PM-MAP) in combination with calcium lactate (1.5% CaL) and cysteine (0.1, 0.5% Cys) immersion pretreatments on the quality preservation of fresh-cut 'Romaine' lettuce was assessed for 12 days, at 5 and 10 °C. The shredded lettuce was packed in low-density polyethylene films (LDPE, 62 µm thickness), including different perforation numbers of 0 (N-MAP), 20 (20-PM-MAP, Diameter = 64 µm), and 40 (40-PM-MAP, Diameter = 64µm) per in square meter. Indices of quality maintenance were investigated. The total microbial counts were below the specified limits for ready-to-eat vegetables (< 6 log CFU/g) considering both pretreated 20-PM-MAP and N-MAP samples on day 12. After 8 days, a significant difference (P < 0.05) was observed in the browning index (BI), the total color difference (ΔE), and the chlorophyll content between N-MAP and 20-PM-MAP samples with better results in 20-PM-MA packages. At 10 °C, the BI in pretreated 20-PM-MAP samples was 32.44% to 58.35% less than N-MAP samples, on the last day of storage. The 20-PM-MAP samples pretreated with 1.5% CaL/0.5% Cys had the highest (P < 0.05) crispness coefficient and water content values. It seems that packaging the pretreated lettuce in 20-PM-MA packages is more effective for maintaining the visual properties (green fresh appearance) of this product, from the 8th to the 12th day of storage. PRACTICAL APPLICATION: The medium to high respiration rate of fresh-cut lettuce causes O2 level drops below its tolerance limit (<1% to 3%) inside the modified atmosphere packaging (MAP). It results in severe browning, off-odors, off-flavor, and growth of anaerobiosis. Perforated-mediated modified atmosphere packaging (PM-MAP) technology can be introduced as an alternative to a nonperforated MAP system (conventional MAP) for fresh-cut lettuce. The application of the PM-MAP system in combination with calcium lactate and cysteine immersion pretreatment (CaL/Cys) may lead to better maintenance of the physicochemical properties of this product.

Factors related to sensory properties and consumer acceptance of vegetables

Many consumers perceive the bitter taste or other sensory characteristic of vegetables as unpleasant, posing a challenge to dietary recommendations aiming to increase vegetable consumption. Food experience is multisensory, with complex interactions between the senses and individual differences in sensory perception. This review focuses on the factors affecting sensory properties of vegetables and sensory perception of vegetables among adults. Topical examples of sensory quality and evaluation of vegetable samples are presented. Cultivar and growing conditions are related to the internal sensory quality of vegetables. The effects of different processing methods, such as freezing and cooking, on the sensory properties of vegetables are also reviewed. Flavor modification of vegetables with seasonings may be used to improve palatability and incorporating vegetables to meals may increase the intake of vegetables. Recently, external factors (e.g. visual and odor stimuli) have been tested in multisensory research in the context of vegetable perception and choice. These options to achieve better sensory quality, more palatable meals and pleasant eating context may be used to promote vegetable intake among adults.

Thermal treatment and modified atmosphere packaging delay chilling injury and preserve the quality of cactus stems (Opuntia ficus-indica Mill.) cv Atlixco

Response surface methodology was applied in order to select the optimal thermal treatment (TT) and modified atmosphere packaging (MAP) needed to preserve minimally processed cactus stems, cv Atlixco. Accordingly, a 42 s/48°C TT together with a 10% CO₂ MAP were selected, and their effects evaluated during storage at 4°C. Controls lost more weight (3.8%) than TT (3.3%), MAP (1.4%), and TT-MAP (1.3%) cactus stems. Chilling injury (CI) symptoms decreased and were of a similar magnitude in both MAP and TT-MAP cactus stems, whereas TT-MAP cladodes were better able to preserve their characteristic green color and freshness, even after 28 days. Biochemically, no differences were detected in the electrolyte leakage (EL) of cactus stems, regardless of treatment. However, the high levels of adenosine triphosphate and of the reduced form of ascorbic acid, especially in MAP and TT-MAP cladodes, suggest that an efficient antioxidant system was present in their tissues throughout storage. PRACTICAL APPLICATIONS: In Mexico, cactus stems have been eaten as vegetables since pre-Hispanic times, and their current status as functional foods has helped them spread to various other countries. As cactus stems possess abundant spines, minimal processing is necessary in order to remove them. Stems must also be kept at 4°C so that their quality and general safety as food items are adequately preserved. However, we previously found that this temperature caused significant CI after just 14 days of storage. The present study, therefore, describes the selection of optimal conditions for the application of a TT that, together with a modified atmosphere (MA), induce tolerance to CI and maintain the quality of stems for up to 28 days. As a result, this work provides the necessary postharvest tools to further expand the distribution and sale of minimally processed cactus stems into domestic and international markets.

Total quality index of Agaricus bisporus mushrooms packed in modified atmosphere

BACKGROUND

The aim of this study was to develop a total quality index and examine the effects of modified atmosphere packaging (MAP) on the quality of Agaricus bisporus mushrooms stored for 22 days at 4 °C. Mushrooms were packaged under three MAPs: high nitrogen packaging (HNP), low carbon dioxide packaging (LCP) and low oxygen packaging (LOP). Passive MAP with air inside initially was used as the atmosphere treatment (AIR).

RESULTS

This research revealed two phases in quality deterioration of A. bisporus mushrooms. During the first week, most of the quality parameters were not statistically different. Thereafter, odor intensities were stronger for all four types of packaging. Color difference and browning index values showed significantly lower color changes for AIR and LOP compared with HNP and LCP mushrooms.

CONCLUSION

The best total quality index was calculated for LOP, followed by LCP and AIR. The findings of this study are useful with respect to examining two-component MAPs, separating the limiting factors (O₂ and CO₂ ) and evaluating quality deterioration effects and the total quality index of A. bisporus mushrooms. © 2016 Society of Chemical Industry.

STUDY OF COMBINED CLEANING PROCESS OF SUNROOT TUBERS

Elaboration and improvement of the process of raw material cleaning is an urgent scientifically technical process. The one of most prospective directions of vegetables cleaning process intensification is the elaboration of combined methods of their cleaning. The improvement of tubers cleaning process is based on the combination of thermal processing of sunroot tubers by steam and the process of further mechanical additional cleaning. The experimental studies of the influence of parameters of the process of sunroot thermal processing by steam on a tuber surface layer transformation were carried out. The influence of the steam pressure and the duration of the process of tubers thermal processing on the depth of the thermal processing of tuber surface layer and also on the effectiveness of the peel separation were studied. At the same time there were realized the studies as to the influence of the duration of tubers mechanical additional cleaning process on cleaning quality parameters. The experimental apparatus and correspondent method that allow to carry out investigations of the combined process of sunroot tubers cleaning with a possibility to determine the influence of all its parameters on the percent of raw material losses and cleaning quality were elaborated. Rational regimes of the combined process of sunroot tubers cleaning were established.

THE STUDY OF INFLUENCE OF THE PROCESS OF MECHANICAL ADDITIONAL CLEANING ON THE SURFACE ONION LAYER AT COMBINED PROCESS OF CLEANING

The one of the ways of solving question of high-quality cleaning of vegetables is the use of combined methods of cleaning, their study and creation of equipment. The improvement of process for its realization and equipment support at trade enterprises, restaurant economy and mini-factories is a topical task. The expedience of elaboration and introduction of combined processes and equipment for their realization at institutions of the restaurant economy and vegetable-processing enterprises give a possibility to exclude the additional equipment for calibration, sorting, washing, additional cleaning. It, in its turn, will provide the safety at production, favoring the more rational use of resources. The one of most prospective directions of intensification of process of cleaning of the vegetable raw material is an elaboration of combined methods and new specialized apparatuses, which work principle is based on combination of the processes of cleaning of product. The experimental setting was elaborated with correspondent methodology that allows carry out the study of process of cleaning of onion with possible determination of influence of all its parameters on the percent of the raw material losses and effectiveness of product cleaning. It is provided due to the presence of work drum in experimental setting that rotates around its axis. The rotation frequency can be changed within the necessary diapason. The work drum has on its surface the special orifices for cutting off the inedible part of onion. The experimental setting also includes tensometric module that allows determine the effort of separation of peel from onion. The use of apparatus for cleaning of onion will give a possibility to intensify process, to improve the quality of cleaning, to decrease the percent of raw material losses.