Fresher Under Pressure Scientific Research
MEAT, POULTRY, AND GAME
Effects of High-Pressure Processing on the Safety, Quality, and Shelf Life of Ready-to-Eat Meats
MM Hayman; I Baxter; PJ Oriordan; CM Stewart
Journal of Food Protection, 1 August 2004, vol. 67, no. 8, pp. 1709-1718(10)
Abstract
Ready-to-eat (RTE) meats (low-fat pastrami, Strassburg beef, export sausage,
and Cajun beef) were pressure treated at 600 MPa, 20°C, for 180 s to evaluate
the feasibility of using high-pressure processing (HPP) for the safe shelf-life
extension of these products. After processing, samples were stored at 4 °C
for 98 days during which time microbiological enumeration and enrichments
were performed. Additionally, sensory analyses were undertaken to determine
consumer acceptability and purchase intent over the duration of storage. Counts
of aerobic and anaerobic mesophiles, lactic acid bacteria, Listeria spp.,
staphylococci, Brochothrix thermosphacta, coliforms, and yeasts
and molds revealed that there were undetectable or low levels for all types
of microorganisms throughout storage. Comparison of consumer hedonic ratings
for unprocessed and processed meats revealed no difference in consumer acceptability,
and no deterioration in the sensory quality was evident for any of the products
tested during the study. Additionally, inoculated pack studies were conducted
to determine if HPP could be used as a postlethality treatment to reduce or
eliminate Listeria monocytogenes and thus assess the potential use
of HPP in a hazard analysis critical control point plan for production of
RTE meats. Inoculated samples (initial level of 104 CFU/g) were pressure treated
(600 MPa, 20 °C, for 180 s) and stored at 4 °C, and survival of L. monocytogenes
was monitored for 91 days. L. monocytogenes was not detected by plating
methods until day 91, but selective enrichments showed sporadic recovery in
three of the four products examined. The results show that HPP at 600 MPa,
20°C, for 180 s can extend the refrigerated shelf life of RTE meats and reduce
L. monocytogenes numbers by more than 4 log CFU/g in inoculated product.
Inactivation of barotolerant Listeria monocytogenes in sausage by combination of high-pressure processing and food-grade additives
YK Chung, M Vurma, EJ Turek, GW Chism, AE Yousef
Journal of Food Protection, 2005 Apr;68(4):744-50
Abstract
Food-grade additives were used to enhance the efficacy of high-pressure processing
(HPP) against barotolerant Listeria monocytogenes. Three strains
of L. monocytogenes (Scott A, OSY-8578, and OSY-328) were compared
for their sensitivity to HPP, nisin, tert-butylhydroquinone (TBHQ), and their
combination. Inactivation of these strains was evaluated in 0.2 M sodium phosphate
buffer (pH 7.0) and commercially sterile sausage. A cell suspension of L.
monocytogenes in buffer (10(9) CFU/ml) was treated with TBHQ at 100 ppm,
nisin at 100 IU/ml, HPP at 400 MPa for 5 min, and combinations of these treatments.
Populations of strains Scott A, OSY-8578, and OSY-328 decreased 3.9, 2.7,
and 1.3 log with HPP alone and 6.4, 5.2, and 1.9 log with the HPP-TBHQ combination,
respectively. Commercially sterile sausage was inoculated with the three L.
monocytogenes strains (10(6) to 10(7) CFU/g) and treated with selected
combinations of TBHQ (100 to 300 ppm), nisin (100 and 200 ppm), and HPP (600
MPa, 28 degrees C, 5 min). Samples were enriched to detect the viability of
the pathogen after the treatments. Most of the samples treated with nisin,
TBHQ, or their combination were positive for L. monocytogenes. HPP
alone resulted in a modest decrease in the number of positive samples. L.
monocytogenes was not detected in any of the inoculated commercial sausage
samples after treatment with HPP-TBHQ or HPP-TBHQ-nisin combinations. These
results suggest that addition of TBHQ or TBHQ plus nisin to sausage followed
by in-package pressurization is a promising method for producing Listeria-free
ready-to-eat products.