Aerobic Package Research Articles

Reduction of biogenic amine and nitrite production in low-salt Paocai by controlled package during storage: A study comparing vacuum and aerobic package with conventional salt solution package

Reduction of biogenic amine and nitrites is of practical importance for promoting the safety of fermented vegetable. The aim of this study was to analyze the efficacy of package types in reducing biogenic amine and nitrite levels of Paocai during storage. And the related parameters including microbial growth, pH and generation of amino acid nitrogen (AAN) were also evaluated. The results showed that when compared with aerobic package (AP) and NaCl solution package (NP), vacuum package (VP) reduced the counts of lactic acid bacteria and yeasts to 6.98 and 1.21 LogCFU/g, respectively. The pH of Paocai was not significantly different among treatments. VP was more effective than AP and NP in suppressing the accumulation of histamine, tyramine and putrescine in Paocai, as evidenced by the contents that were 0.19, 0.15 and 0.43 mg/kg after storage, respectively. Additionally, VP and AP prevented cadaverine production throughout the storage while NP accelerated its production. For Paocai in VP and NP, the AAN content rose by 66.67% and 33.33%, respectively, while AAN in AP increased by 133.33% after storage. Meanwhile, nitrite accumulation in Paocai was mitigated by VP, as shown by nitrite content that were 56.04% and 36.31% lower than those in AP and NP groups, respectively, at the end of storage. Therefore, compared with conventional NP, VP was the most effective in suppressing the production of biogenic amines, nitrite and AAN, while AP accelerated the accumulation of these nitrogenous compounds, possibly implicated the application of VP to produce fermented vegetable with higher safety property.

Effects of Package Atmosphere and Storage Conditions on Minimizing Risk of Escherichia coli O157:H7 in Packaged Fresh Baby Spinach

Packaged fresh spinach has been associated with outbreaks of illness caused by Escherichia coli O157:H7. The purpose of this study was to assess the behavior of E. coli O157:H7 in packaged baby spinach in response to storage conditions of temperature and package atmosphere and including effects of inoculation level, spinach leaf damage (cut leaves), internalized or leaf surface contamination, exposure to hypochlorite sanitizer, and package size. Behavior of E. coli O157:H7 inoculated at 2 and 4 log CFU/g on spinach packaged in polymer bags composed of a two-layer laminate (polypropylene and polyethylene) and stored under atmospheres of 20% O2-3% CO2 and 0% O2-15% CO2 (aerobic and anaerobic, respectively) was assessed at 5, 7, 12, and 15°C for up to 14 days. Growth kinetics were calculated using DMFit software. Temperature decreases progressively diminished growth or survival of the pathogen, and an aerobic package atmosphere resulted in longer lag times (4 to 6 days) and lower population levels (0.2 to 1.4 log CFU/g) compared with the anaerobic atmosphere at 15°C. Internalized contamination, leaf cuts, or exposure to 100 ppm of hypochlorite did not result in changes in pathogen behavior compared with controls; however, a growth minimization trend consisting of longer lag times and lower population levels was repeatedly observed in the aerobic compared with the anaerobic package atmospheres. In contrast, growth of indigenous mesophiles and Enterobacteriaceae was unaffected by package atmosphere. Spinach stored at 5 to 7°C in two sizes (5 and 16 oz) of polyethylene terephthalate clamshell packages with ambient air atmospheres was more likely to progress to lower-oxygen conditions in 16-oz compared with 5-oz packages after 7 days of storage (P < 0.05). Practices to maintain aerobic conditions within the package, as well as storage of the package at low temperature, are ways to limit growth of E. coli O157:H7 in packaged spinach.

The effects of vacuum and modified atmosphere packaging on quality changes in seasoned cobia (Rachycentron canadum) sticks stored under refrigeration

Abstract The objective of this research was to compare the quality attributes of seasoned cobia sticks packed under vacuum and using modified atmosphere packaging (MAP) and stored under refrigeration, as well as to establish the most suitable gas mixtures to maintain product freshness and provide an extended shelf life. The seasoned cobia sticks were breaded with a mixture of dehydrated spices (parsley, onion, garlic, tomato and bacon), packaged under vacuum; 100% aerobic package (control, with the presence of atmosphere air); MAP1 (15% N2 + 80% CO2 + 5% O2), and MAP2 (20% N2 + 70% CO2 + 10% O2 ), and stored at 5°C for 28 days. Samples were taken every 72 hours for the microbiological analyses (total mesophilic count, total psychrotrophic count, coagulase positive Staphylococcus, Salmonella sp., and thermotolerant Coliforms at 45°C) and physicochemical analyses (pH, the nitrogen from the total volatile bases, and trimethylamine), all carried out in triplicate. The results showed that the seasoned cobia sticks remained safe and with good microbiological, physical and chemical quality for a longer period when packed in a modified atmosphere. MAP1 (15% N2 + 80% CO2 + 5% O2) was the system showing the best performance in the maintenance of quality and freshness, demonstrating the feasibility of ensuring quality and a longer shelf life (28 days) at 5°C.

Treatment of catfish processing wastewater by the combination of anaerobic and aerobic package cage rotating biological contactors

The study aimed to diversify the treatment technology of catfish processing wastewater. The experiments were implemented on lab-scale package cage rotating biological contactors with the first stage in anaerobic condition and the second stage in the aerobic condition, using PVC flexible conduit medium. The selected hydraulic retention time of anaerobic stage was 12 hours, and that of aerobic rotating package cage biological contactor was 4 hour 12 minutes. The results showed that almost monitoring parameters (pH, SS, DO, COD, BOD5, TKN, Ptotal) met the national standards of QCVN 11-MT:2015/BTNMT (column A), except +NH4 only reached the QCVN 11-MT:2015/BTNMT (column B). The results confirmed that combining both anaerobic and aerobic package cage rotating biological contactors with PVC flexible conduict medium could apply to treat catfish processing wastewater.

Modified Atmosphere Packaging and UV-C Radiation on Shelf Life of Rainbow Trout (Oncorhynchus Mykiss)

Effects of modified atmosphere packaging (MAP) in combination to UV-C radiation on rainbow trout fillets were examined. The samples were submitted to two treatments: (T1) aerobic package; (T2) MAP+UV-C radiation (80% CO2/20% N2; 106.32mJ/cm2) and were analyzed daily for microbiological (mesophilic and psychrotrophic count) and chemical (biogenic amines) parameters. MAP+UV-C radiation (T2) promoted lag phase formation and lower number of colonies in the stationary phase as well as retarded cadaverine production during storage time. MAP+UV-C radiation retard microbial growth and delay chemical changes enhancing the shelf life of rainbow trout fillets by at least twice.

Effects of Addition of Tomato Powder on Colour, Antioxidant, and Antimicrobial Traits of Pork Jerky during Storage

The aim of this study was to investigate the effects of the addition of tomato powder [1.0% (T1), 1.5% (T2) and 2.0% (T3)] on pork loin jerky with aerobic package during storage at room temperature. The T3 sample showed lower (p<0.05) pH value and higher (p<0.05) water activity than the control during storage. Total plate counts of treated samples (<TEX>${\geq}1.20$</TEX> Log CFU/g) were significantly (p<0.05) lower than the control (1.46 Log CFU/g) during storage. With the increase of the tomato powder concentration the lightness (<TEX>$L^*$</TEX>) of the jerky decreased, except at day 30 of storage, but the redness (<TEX>$a^*$</TEX>) and yellowness (<TEX>$b^*$</TEX>) increased significantly (p<0.05) during storage. T3 had higher values for hardness and cohesiveness but lower for springiness, gumminess and chewiness than others at day 40 of storage. However, there were no significant differences in TBARS values among the samples during storage. In sensory properties, the color scores of T3 was significantly (p<0.05) higher than that of control at day 40 of storage. These results suggested that 2.0% tomato powder could be used to improve the redness and extend the shelf-life of jerky with increasing water activity, providing the consumer with food containing natural colorant.

Biogenic amine formation in turkey meat under modified atmosphere packaging with extended shelf life: Index of freshness

The aim of this study was to evaluate the effect of modified atmosphere packaging (MAP) on biogenic amine production in turkey meat according to its shelf life period, determining an index of freshness. Sliced meat samples of different meat quality categories (according to color and pH₂₄) were individually packaged under aerobiosis (aerobic package) and in 6 different modified atmospheres containing different gas mixtures: MAP1, 50% N₂/50% CO₂; MAP2, 0.5% CO/50% CO₂/49.5% N₂; MAP3, 50% Ar/50% N₂; MAP4, 0.5% CO/80% CO₂/19.5% N₂; MAP5, 100% N₂; and MAP6, 50% Ar/50% CO₂. All samples were stored at 0 ± 1°C in the dark for between 12 and 25 d. Meat samples packaged in aerobic packaging were analyzed for their microbial and physicochemical characteristics on d 0, 5, and 12 of storage, and then extended to 19 and 25 d when samples were under MAP. The production of biogenic amines analyzed in turkey meat increased over time. The values of putrescine, cadaverine, and tyramine increased significantly (P < 0.05) during storage time in samples packaged under aerobiosis, MAP3, and MAP5. Histamine was not detected in turkey meat packaged under study conditions, or when present, the levels were below the limit of quantification (1.03 mg/kg). Tyramine in turkey meat under MAP was not the best amine indicator of meat deterioration, with cadaverine being suggested instead, or the sum of the amines putrescine, cadaverine, and tyramine, to characterize and quantify meat freshness. After 25 d of storage, the meat packaged under MAP with a mixture containing a higher concentration of CO₂ and with CO was the one with a lower index value (11.36 mg/kg), although not significantly different from the indices provided by the meat packaged with MAP1, 2, and 6.

Effect of Whey Protein Coating on Quality Attributes of Low‐Fat, Aerobically Packaged Sausage during Refrigerated Storage

Whey protein-based edible coating was used to reduce oxidative degradation and microbial growth of low-fat sausages (LFSs) stored at 4 degrees C for 8 wk, under aerobic package. Whey protein coating reduced (P<0.05) thiobarbituric acid-reactive substances (TBARS) and peroxide value (PV) formation compared to control sausages. The percent inhibition of TBARS and PV for whey protein-coated sausages, compared to the control, was 31.3% and 27.1%, respectively. The ability of the whey protein coating to provide a moisture barrier for the sausages was reduced (P<0.05). In addition, a reduction of moisture loss by 36.7% compared to the control was achieved by whey coating. However, whey protein coating of LFSs did not inhibit the growth of either the total number of aerobic bacteria or of Listeria monocytogenes. These results indicated that whey protein coating had an antioxidative activity in LFSs under aerobic package during refrigerated storage.

Evaluation of a single‐residence biological wastewater treatment system with thermal biosolids destruction

An aerobic package residential wastewater treatment system was evaluated to determine process performance while connected to a single‐family residence. Three components of the study were: 1) long‐term (5‐month) performance, 2) 24‐hour performance track studies, and 3) enhanced loading study. For the long‐term performance and enhanced loading study hourly influent and effluent samples were collected and composited on a flow‐averaged basis. Short‐term fluctuations in flow and mass loading rates were evaluated from the hourly discrete samples. The long‐term average removals for CBODs, TSS, and inorganic N were 97.3, 97.8 percent, and 89.6 percent, respectively, with average effluent concentrations of 5.7, 5.9, and 2.2 mg l−1. To prevent biosolids buildup in the system and to eliminate the need for frequent sludge removal a thermal process is incorporated into the system for biosolid ash conversion. Periodic spikes of influent mass loading rates persisted in the treatment system at time scales of one hour or less. Treatment process performance, evaluated from 24‐hour composite samples, was not affected by the highly variable influent concentrations and flow rates experienced in the study single‐family household. Average monthly power consumption for aeration, thermal processing of accumulated biosolids, and biomass re‐circulation was 132 kWh per month, or about 4.4 kWh per day

Oxygen Transfer Efficiency in Small Diffusers

Small on-site aerobic package plants are one alternative being explored to address situations in which septic-tank and leach-field systems are not appropriate or feasible. Such small aerobic systems use either mechanical-aeration or forced-air diffusers. However, the only information available in the literature on designing the aeration systems pertains to large-scale facilities. Oxygen-transfer characteristics of diffusers in shallow systems should be significantly different from those reported in the literature for deeper systems. This paper reports on a laboratory study conducted at the Environmental Technology Laboratory at the University of Alaska, Fairbanks, analyzing the oxygen-transfer characteristics of small diffusers. Data show that diffusers typically used in small on-site aerated wastewater-treatment systems provide lower overall oxygen transfer on a mass basis, but actually transfer oxygen at a faster rate than diffusers in deep tanks reported in the literature. The present research provides basic data of importance for the design of small wastewater-treatment systems using diffusers.

Onsite aerobic package treatment systems

Several studies were conducted to evaluate the performance of onsite aerobic package treatment systems (APTS), and to suggest operational and design modifications. In the first phase, five APTS in southwest Virginia were found to be operating poorly (average BOD 5 = 69.4 mg/l, TSS = 99 mg/l, TKN = 18.6 mg/l), often violating Virginia effluent standards. Mechanical failures, improper maintenance and design were identified as causing the poor performance. In the second phase, excessive hydraulic retention time (HRT) in field systems (over 3 days) was identified as a significant design problem. Laboratory systems operating with aeration basin HRTs of 0.5 to 2 days produced better effluent quality (average BOD 5 = 19 mg/l, TSS = 29 mg/l, TKN = 0.7 mg/l). In a separate experiment relatively high levels of laundry detergent did not significantly affect laboratory system performance. Finally, a field experiment was conducted to determine the effect of equalizing washing machine flow on the operation of an APTS. An improvement in system performance and stability was observed. Based on these studies, potential design and operational modifications are suggested, including improved maintenance, reduction of aeration basin HRT, and equalization of wastewater flow.