Aerobic Psychrotrophs Research Articles

Chemical and microbiological characterization of “samburá” from two stingless bee species

The pollen stored by stingless bees (samburá) is a product of the hive considered a functional food. However, few studies related to this promising product for human consumption are found in the literature. Thus, the aim of this study was to evaluate the chemical and microbiological characteristics of samburá from two species of stingless bee. The samples were submitted to chemical (moisture, ash, pH, acidity, water activity, proteins, lipids, total carbohydrates, total phenolic compounds, total flavonoids) and microbiological analyses (coliforms 35 °C and 45 °C, Staphylococcus coagulase positive, Clostridium sulphite reducers, Salmonella spp., aerobic mesophiles, aerobic psychrotrophs, molds, and yeasts). The results showed differences in samburá composition in both species, complying with the threshold established by the Brazilian legislation for bee pollen, except for moisture content (26.96 − 30.11%), ash (4.92 − 5.41%) and pH (3.47 − 3.42) in samburá of T. angustula and S. xanthotricha, respectively. Samburá S. xanthotricha had higher values for moisture (30.11%), ash (5.41%), water activity (0.78 Wa), acidity (120.93 mEq kg−1), and total flavonoids (20.94 mgEQ g−1). No microorganisms that compromise product quality (spores of Clostridium sulphite reducers and Salmonella spp.), health quality (coliforms at 45 °C and Staphylococcus coagulase positive), or commercial quality (psychrotrophic aerobes) were observed in the samples. Samburá of both species displayed different chemical characteristics and good nutritional conditions, constituting promising products for human food and were also safe for consumption, as no pathogenic microorganisms were detected.

Current knowledge on the microbiota of edible insects intended for human consumption: A state-of-the-art review.

Because of their positive nutritional characteristics and low environmental impact, edible insects might be considered a 'food of the future'. However, there are safety concerns associated with the consumption of insects, such as contaminating chemical and biological agents. The possible presence of pathogenic and toxigenic microorganisms is one of the main biological hazards associated with edible insects. This review presents an overview of the microbiota of edible insects, highlighting the potential risks for human health. Detailed information on the microbiota of edible insects from literature published in 2000-2019 is presented. These data show complex ecosystems, with marked variations in microbial load and diversity, among edible insects as well as stable and species-specific microbiota for some of the most popular edible insect species, such as mealworm larvae (Tenebrio molitor) and grasshoppers (Locusta migratoria). Raw edible insects generally contain high numbers of mesophilic aerobes, bacterial endospores or spore-forming bacteria, Enterobacteriaceae, lactic acid bacteria, psychrotrophic aerobes, and fungi, and potentially harmful species (i.e. pathogenic, mycotoxigenic, and spoilage microbes) may be present. Several studies have focused on reducing the microbial contamination of edible insects by applying treatments such as starvation, rinsing, thermal treatments, chilling, drying, fermentation, and marination, both alone and, sometimes, in combination. Although these studies show that various heat treatments were the most efficient methods for reducing microbial numbers, they also highlight the need for species-specific mitigation strategies. The feasibility of using edible insects as ingredients in the food industry in the development of innovative insect-based products has been explored; although, in some cases, the presence of spore-forming bacteria and other food-borne pathogens is a concern. Recent studies have shown that a risk assessment of edible insects should also include an evaluation of the incidence of antibiotic-resistance (AR) genes and antibiotic-resistant microorganisms in the production chain. Finally, as proposed in the literature, microbial hazards should be limited through the implementation of good hygienic practices during rearing, handling, processing, and storage, as well as the implementation of an appropriate HACCP system for edible insect supply chains. Another issue frequently reported in the literature is the need for a legislative framework for edible insect production, commercialisation, and trading, as well as the need for microbiological criteria specifically tailored for edible insects. Microbiological criteria like those already been established for the food safety and hygiene (e.g. those in the European Union food law) of different food categories (e.g. ready-to-eat products) could be applied to edible insect-based products.

Postharvest conservation of minimally processed cassava roots subjected to different packaging systems

Cassava ( Manihot esculenta Crantz) is one of the main energy sources in human food, being largely consumed and produced in Brazil. However, it is not easy to prepare and has a high deterioration degree after harvest. As an alternative, producers and agribusinesses are extensively using vacuum packaging for the storage of minimally processed cassava roots. This study evaluates the postharvest conservation of minimally processed cassava roots packed in 130 μm, 200 μm, and 300 μm LDPE packages with and without vacuum, stored at 3 °C and 90% relative humidity. Samples were evaluated every seven days for a period of 28 days for pH, titratable acidity, so­luble solids, SS/TA ratio, texture, fresh weight loss, moisture, dry matter, cooking time, color (L*, a*, b*, increase in browning, chroma, and hue angle), and microbiology (counting mesophilic aerobes, psychrotrophic aerobes, molds and yeasts, total and thermotolerant coliforms). Minimally processed cassava roots packed in LDPE pack­ages with higher thickness (200 μm and 300 μm) show greater stability in physicochemical and microbiological components. For packages 200 μm vacuum LDPE and 300 μm LDPE in the two atmosphere conditions, stored at 3 oC and 90% relative humidity, the shelf life of minimally processed cassava roots was 14 days. The recom­mended storage period for the remaining treatments is seven days.

In vivo and in vitro effects of selected antioxidants on rabbit meat microbiota

The purpose of this study was to investigate the effect of dietary vitamin E or EconomasE™ supplementation on the growth of several background/pathogenic bacteria on rabbit carcasses and hamburgers during refrigerated storage. For 51days, 270 New Zealand rabbits received either a basal diet, or experimental diets enriched with 100 or 200mg/kg of vitamin E or EconomasE™. The bacteria studied were Salmonella, Listeria monocytogenes, Pseudomonas, Enterobacteriaceae, Escherichia coli, coagulase-positive staphylococci, plus both mesophilic and psychrotrophic aerobes. The growth of Listeria monocytogenes on contaminated patties was evaluated through a challenge test. The potential protective or antimicrobial effect of vitamin E or EconomasE™ on Listeria monocytogenes or Pseudomonas aeruginosa was assessed in vitro. Diet did not influence the concentrations of bacteria found on rabbit carcasses and developing on hamburgers. Vitamin E (in vivo and in vitro) and EconomasE™ in vivo had a protective antioxidant role, while EconomasE™ in vitro had strong antibacterial activity against Listeria monocytogenes, but not against Pseudomonas aeruginosa.

The effect of cinnamon, oregano and thyme essential oils in marinade on the microbial shelf life of fish and meat products

Fresh and minimally processed fish and meat are easy targets for microbial spoilage. The demand for natural alternatives to synthetic additives increases. In this study essential oil (EOs) in marinades were used on fish and meat and the effect on the microbial growth during storage was assessed. EOs from Oreganum compactum (oregano), Cinnamomum zeylanicum (cinnamon), and Thymus zygis ct. Thymol (thyme) were chosen. The marinade was composed of water, Na-lactate/lactic acid buffer (2 w/w %), NaCl (10 w/w %), and EO emulsified with Tween 80 and with a pH of 4.5. The necessary Tween 80 to emulsify the EOs in the marinade depended on the EO type and was increased more than tenfold by the NaCl and lactate buffer. The treatment consisted of immersion of meat (pork filet, pork bacon, chicken filets, chicken skin), salmon or scampi for 2 min in marinade solution. The samples were stored at 4 °C in air. Samples were analyzed for microbial counts (dependent on matrix: total coliforms, Escherichia coli, lactic acid bacteria, yeasts and molds, total aerobic psychrotrophs). Growth inhibition was achieved with some EO + marinade treatments but marinade itself did not slow down the microbial growth. Most notably, the growth of yeasts and molds was inhibited by immersion of all food matrices in 1 w/w % cinnamon EO. Use of (1 w/w % for all EO) cinnamon EO (+marinade) led to microbial shelf life increase of all matrices (except the chicken matrices as the end of the shelf life was not reached during the experimental duration), oregano EO to shelf life increase of pork filet and salmon, and thyme EO of pork filet and scampi. Sensorial analysis on pork filet and salmon showed that immersion in 3% EO (resulting in 0.09 g EO/100 g pork filet and 0.05 g EO/100 g salmon) resulted in an acceptable odor after 24 h of storage. The results in this study show that the sensorial properties of the meat/fish are inevitably affected when the necessary EO concentrations to extend the microbial shelf life are applied.

SANITIZERS ON MICROBIOLOGICAL QUALITY OF STRAWBERRIES ‘OSO-GRANDE’

The objective of this study was to evaluate the effect of two disinfectants on the microbiological quality of strawberries cv. ‘Oso-grande’ in nature sold in Lavras, MG, and stored for 6 days at room temperature. 5 treatments were used (control, sodium hypochlorite 100 and 200 mg L-1 and sodium dichloroisocyanurate (Hidrosan ®) 100 and 200 mg L-1 for 15 min) and 3 days of analysis, corresponding to days 0, 3 and 6, with 4 replicates of 10 fruits for each treatment. Microbiological tests performed were: coliform count at 35 o C and heat tolerant, detection of salmonella spp., Aerobic psychrotrophs counts, isolation and identification of fungi and yeast counts. The dichloroisocyanurate and 200 mg L-1 inhibited the growth of filamentous fungi and psychrotrophs and the yeast count was lower when compared with other treatments.

A simple method to evaluate the shelf life of refrigerated rabbit meat

The shelf life of rabbit meat during refrigerated storage was investigated under industrial conditions. Rabbit carcasses were bulk packed (BP), packed under air (PUA) and under modified atmosphere (MAP) (30% O2:40% CO2:30% N2). The main groups studied were mesophilic aerobes, psychrotrophic aerobes, Pseudomonas spp., lactic acid bacteria, yeast and moulds and Enterobacteriaceae. The microorganisms that showed faster growth were psychrotrophic aerobes (growth rate of 0.36 ± 0.09 day−1) for BP, Pseudomonas (0.26 ± 0.03 day−1) for PUA, and lactic acid bacteria (0.22 ± 0.01 day−1) for MAP, and the lag phases were 4, 4 and 8 days, respectively. The main effect of MAP was the increase in lag phase from 4 to 8 days, for lactic acid bacteria, psychrotrophic and mesophilic aerobes. The respective growth rates were similar to those observed with PUA. In addition, MAP inhibited Pseudomonas growth during 18 days. Considering 6 log CFU g−1 as maximum tolerable microbial load, the calculated values of shelf life in BP, PUA and MAP were 6, 7 and 12 days, respectively, when considering the fastest growing microorganisms.

Effect of illumination on the display life of fresh pork sausages packaged in modified atmosphere. Influence of the addition of rosemary, ascorbic acid and black pepper

Pork forelegs were used for manufacturing fresh sausages, treated with different natural antioxidants (rosemary, ascorbic acid and black pepper), packaged in 80% O 2 + 20% CO 2 atmosphere and displayed at 2 ± 1 °C under different lightings (darkness, standard fluorescent, low-UV colour-balanced lamp and standard fluorescent plus a UV-filter). Two packs for each treatment were opened every 4 days for subsequent analysis of colour CIE L ∗, a ∗, b ∗, TBARS, microbial psychrotrophic aerobes and sensory discolouration and off-odour. Lighting with standard fluorescent was highly deleterious for sausage display life, which fell from 12 to 8 days due mainly to early discolouration. Inserting a UV-filter extended display life to 12 days, while the use of a low-UV lamp was not effective in protecting from discolouration. Addition of rosemary plus ascorbic acid, in the absence of black pepper, retarded discolouration only in sausages illuminated with the UV-filter, reaching a display life of 16 days, equal to that of sausages maintained in the dark.

Combined Effect of Modified Atmosphere Packaging and Addition of Rosemary (Rosmarinus officinalis), Ascorbic Acid, Red Beet Root (Beta vulgaris), and Sodium Lactate and Their Mixtures on the Stability of Fresh Pork Sausages

The effects of rosemary, in combination with ascorbic acid, red beet root, and sodium lactate, as well as their mixtures, on the inhibition of both lipid and pigment oxidation of fresh pork sausages packaged in a modified atmosphere were studied. Sausages (240) were packaged in a 80% O2 + 20% CO2 gas mixture and analyzed for CIE a, metmyoglobin, TBARS, psychrotrophic aerobes, and sensory discoloration and off-odor throughout 20 days of storage at 2 +/- 1 degrees C. The mixture of rosemary + ascorbic acid + sodium lactate + red beet root extract extended the shelf life of fresh pork sausages from 8 to 16 days. Results demonstrated that all of the components of the mixture contributed to obtaining the maximum delay in color and/or odor decay, due to a combined inhibitory action on both pigment and lipid oxidation, as well as on microbial growth.

Effect of Capsicum annuum (Red Sweet and Cayenne) and Piper nigrum (Black and White) Pepper Powders on the Shelf Life of Fresh Pork Sausages Packaged in Modified Atmosphere

ABSTRACT Capsicum annuum (red sweet and hot cayenne) and Piper nigrum (black and white) pepper powders were evaluated for inhibition of oxidative reactions and extension of the shelf life of fresh pork sausages packaged in a modified atmosphere. Sausages containing either red sweet pepper or cayenne pepper (0.1%, 0.5%, or 2%) or black or white pepper (0.1%, 0.5%, or 1%) were packaged in a modified atmosphere of 80% O2+ 20% CO2, stored for 16 d in the dark at 2 °C, and analyzed each 4 d for pH, CIE L*, a*, and b*, 2‐thiobarbituric acid‐reactive substances (TBARS), psychrotrophic aerobes, sensory discoloration, and off‐odor. Results demonstrated that Capsicum peppers (sweet red and hot cayenne) enhanced red color but failed to prevent discoloration, whereas they were very effective in inhibiting lipid oxidation, chiefly at the highest concentration used (2%), which resulted in a delay of off‐odor formation. Piper peppers (black and white) significantly delayed discoloration with small modification of sausage color; furthermore, they also inhibited lipid oxidation, which led to a delay of off‐odor formation, particularly in the form of black pepper. Besides this, all those spices inhibited microbial growth when added at the highest concentration (1%Piper and 2%Capsicum).

GROWTH DYNAMICS OF INDIGENOUS MICROBIAL POPULATIONS ON VEGETABLES AFTER DECONTAMINATION AND DURING REFRIGERATED STORAGE

To ensure microbiological stability and safety in minimally processed (MP) salad vegetables, it is essential to consider the microbiology of this produce during cultivation and harvesting, and the potential changes to this microbiology through preparation, distribution and storage. This study takes two salad vegetables (lettuce and white cabbage) and, having enumerated a range of different physiological groups of microorganisms present on unwashed produce, determines the impact on each microbial group of applying a decontamination step in the preparation protocol. The disinfectant used was sodium dichloroisocyanurate. Decontamination reduced the total microbial load significantly on both vegetables. The levels of different microbial groups enumerated differed significantly between vegetables. All the microbial populations were reduced, but the biocidal effect of chlorine treatment varied with vegetable type. Reduction of the levels of lactic acid bacteria and aerobic psychrotrophs on cabbage was only achieved with inclusion of the decontamination step, and this effect, in general, did not last more than 3 days. Decontamination significantly reduced the levels of coliforms, and although the levels increased during refrigerated storage, they did not exceed initial levels found on unwashed produce. In addition, the levels found on treated cabbage remained lower than produce washed with water only.

5569424 Method and apparatus for recycling waste composite material : Amour William Monroe, WA, United States

The purpose of this study was to investigate the effect of dietary vitamin E or EconomasE™ supplementation on the growth of several background/pathogenic bacteria on rabbit carcasses and hamburgers during refrigerated storage. For 51 days, 270 New Zealand rabbits received either a basal diet, or experimental diets enriched with 100 or 200 mg/kg of vitamin E or EconomasE™. The bacteria studied were Salmonella, Listeria monocytogenes, Pseudomonas, Enterobacteriaceae, Escherichia coli, coagulase-positive staphylococci, plus both mesophilic and psychrotrophic aerobes. The growth of Listeria monocytogenes on contaminated patties was evaluated through a challenge test. The potential protective or antimicrobial effect of vitamin E or EconomasE™ on Listeria monocytogenes or Pseudomonas aeruginosa was assessed in vitro. Diet did not influence the concentrations of bacteria found on rabbit carcasses and developing on hamburgers. Vitamin E (in vivo and in vitro) and EconomasE™ in vivo had a protective antioxidant role, while EconomasE™ in vitro had strong antibacterial activity against Listeria monocytogenes, but not against Pseudomonas aeruginosa.

Low‐dose Gamma Irradiation and Refrigerated FStorage in vacua Affect Microbial Flora of Fresh Pork

ABSTRACTVacuum‐packaged ground fresh pork samples absorbed gamma radiation doses of 0. 0.57. 1.91. 3.76. 5.52. or 7.25 kGv at 2°C. Samolcs were analyzed after 1, 7, 14, 21, 28,‘or 35 days itorage at 2°C’for presence and number of aerobic and anaerobic mesophiles and endospore formers, and aerobic psychrotrophs. Conventional plate counts did not detect surviving microflora in any sample that received an absorbed dose of 1.91 kGy or higher, even after refrigerated storage for up to 35 days. The microflora in the control were predominantly Gram‐positive for the first 21 days; however, Serratia predominated at 28 and 35 days. Staphylococcus, Micrococcus, and yeast species predominated in samples that received 0.57 kGy.

Effect of spray-chilling on quality of beef from lean and fatter carcasses.

Carcasses from five trim cows and five choice steers were used to study the effects of spray-chilling on cooler shrink, chill rate, purge loss from vacuum-packaged cuts, cook loss, shear values and bacterial growth. Spray-chilling reduced cooler shrink but had no effect on chill rate, purge loss from vacuum-packaged cuts, cook loss or shear values. Aerobes, facultative anaerobes, aerobic psychrotrophs, facultative anaerobic psychrotrophs and lactic acid bacteria all tended to be higher on rounds from spray-chilled sides. Leaner (and lighter) cow carcasses chilled faster and had lost a higher percentage of their weight at 24 h than fatter and heavier steer carcasses. The leaner carcasses had higher bacterial counts initially and throughout storage. This difference may have been due to differences in the level of initial contamination during dressing and not due to the carcasses' leanness. Purge-weight loss for each carcass increased and cooking weight loss decreased with increased storage times, making the total weight loss from meat aged 5 vs 10 wk similar.

Some microbiological assays of ground beef blended with hydrogenated soybean oil

Ground beef patties were formulated from beef lean, beef fat and hydrogenated soybean oil. Using the Pearson Square Method, the patties were formed to contain three total fat levels (16,20 and 24%). At each level, vegetable fat was substituted for 0,25 or 50% of total fat to end up with nine different blends. Aerobic psychrotrophs and mesophiles of the blends were investigated at 0−, 3− and 6-day intervals. A split-split plot design with two replications was used to differentiate significant and non-significant attributes of the main effect and the corresponding interactions. Results obtained show that total fat level, percentage vegetable fat or replication did not have a significant effect on bacterial numbers of ground beef extended with hydrogenated soybean oil of 70 iodine value. However, the days of storage significantly ( P <0·001) affected both the Standard Plate Count (SPC) and Psychotrophic Plate Count (PPC). The log number of bacteria in both SPC and PPC continued to increase with length of storage. In all the cases studied PPC was found to be higher than SPC, which indicates that the predominant microflora in raw beef products is psychrotrophic in nature.

Growth of Aerobic Psychrotrophs and Color Changes of Precooked Beef Slices as Affected by Packaging Procedure

Precooked beef slices from top round roasts were used in replicate trials to determine the effects of packaging treatment upon shelf-life characteristics (microbial growth and color attributes) during retail storage. Roasts were dry-roasted to an internal temperature of 60°C, cooled for 1 h, then sliced (3–4 mm). Slices were packaged in: (a) vacuum; (b) 15% CO2, 40% O2, 45% N2; (c) 15% CO2, 20% O2, 65% N2; or (d) 15% CO2, 10% O2, 75% N2 and held at 4°C for up to 18 d. Enumeration of microorganisms and determination of color attributes were done at 0, 3, 6, 9, 12, 15, and 18 d of storage. Psychrotrophic counts were higher (P<.05) on slices stored 9–18 d in atmospheres containing ambient (20%) oxygen level as compared to the other packaging treatments. Vacuum packaging exhibited a greater lag phase for psychrotrophs. Vacuum packaged slices maintained a superior cooked beef color for 18 d and had greater (P<.05) chroma readings, indicating a greater color intensity.

Bacteriology and Weight Loss of Pork Carcasses Treated with a Sodium Hypochlorite Solution

One hundred thirty-two pork carcasses were used with 36 of these receiving a wash with tap water and 96 receiving a wash with tap water plus 200 ppm of sodium hypochlorite. The first trial involved 16 carcasses measured for total aerobic psychrotrophs. A reduction (P<.05) in the bacterial level was found on those carcasses sprayed for 10 min with a 200 ppm sodium hypochlorite solution. Three additional trials involved 116 carcasses that were measured for degree of shrinkage after a 24 h chill. Shrinkage was reduced (P<.01) from a high of 2.46% for the controls to slight increases in weight for those treated for 30 min. Generally there was a linear relationship with reduction of shrinkage and length of spraying with a 200 ppm sodium hypochlorite solution.

Bacteriology of Restructured Lamb Roasts Made with Mechanically Deboned Meat

Composite samples of restructured lamb roast containing 10 or 30% mechanically deboned meat (MDM) were analyzed for bacteriological quality before and after cooking to 62.8°C (145°F). Uncooked samples had less than 3.0 × 104 colony forming units/g mesophilic and psychrotrophic aerobes and anaerobes including lactobacilli. In general, these groups, as well as coliforms and fecal coliforms, were present in higher numbers in uncooked roasts containing higher percentages of MDM. Staphylococcus aureus, Clostridium perfringens, Salmonella sp., Yersinia enterocolitica and Campylobacter jejuni were not detected in uncooked samples. Cooking reduced the number of aerobic and anaerobic spoilage bacteria and eliminated index bacteria (in 0.1 g) effectively.

INFLUENCE OF PRERIGOR AND POSTRIGOR MUSCLE ON THE BACTERIOLOGICAL AND QUALITY CHARACTERISTICS OF PORK SAUSAGE

ABSTRACTThe right and left sides of three market‐weight pigs were assigned to two treatments, designated prerigor and postrigor, for pork sausage manufacture. Muscle and fat were obtained from the right side within 1 hr after slaughter and were immediately processed into sausage referred to as prerigor sausage. The left side of the carcass was chilled for 6 days at 2°C. The sausage made from this tissue is referred to as postrigor sausage. The sausage samples were stuffed into 0.45‐kg packages and stored at 2–5°C or °22°C for 8 wk. The pH values, bacterial counts, cooking loss and taste palatability traits were investigated on fresh and frozen samples representing the prerigor and postrigor groups. The prerigor sausage samples stored at 2–5°C had significantly higher pH values, higher total aerobic mesophiles and lipolytic bacterial counts, higher juiciness and overall acceptance scores and a lower cooking loss than did the samples prepared from the postrigor muscle. No significant difference was found in total aerobic psychrotrophs and flavor score, but the sausage made from prerigor muscle had slightly higher values. The period of storage at 2–5°C influenced the bacterial counts and 911 taste panel scores. The sausage stored at °22°C was similar to the nonfrozen samples for taste panel comparisons.

MICROBIOLOGICAL FEATURES OF TERRESTRIAL SITES ON THE DEVON ISLAND LOWLAND, CANADIAN ARCTIC

Bacterial populations of the Devon Island Lowland consist mainly of psychrotrophic aerobes and facultative types, with counts falling within temperate zone limits. Nitrification and sulphate reduction appear restricted but denitrification potential is considerable. Peat polygon and mesic meadow areas have the highest microbial activities, the polar desert the least.