No abstract

Surimi seafood is a cooked gel product that utilizes fish protein from surimi to produce seafood analog products. Starch is the second most important ingredient used in the manufacture of surimi seafood due to its water holding ability and capacity to partially replace fish proteins while maintaining desired gel characteristics at a reduced cost. Typically, starch is added to surimi seafood formulations at 4-12%. Functional properties of surimi seafood to control wetness, stickiness, and/or thermal stability upon different storage and serving temperatures have been extensively studied using modified starches. There is a great need to review the role of starches in various applications of surimi seafood.

The objective of this study was to determine the effectiveness of packaging films coated with a methylcellulose/hydroxypropyl methylcellulose-based solution containing 10,000, 7,500, 2,500, or 156.3 IU/ml nisin for controlling Listeria monocytogenes on the surfaces of vacuum-packaged hot dogs. Barrier film coated with a methylcellulose/hydroxypropyl methylcellulose-based solution containing nisin or no nisin (control) was heat sealed to form individual pouches. Hot dogs were placed in control and nisin-containing pouches and inoculated with a five-strain L. monocytogenes cocktail (approximately 5 log CFU per package), vacuum sealed, and stored for intervals of 2 h and 7, 15, 21, 28, and 60 d at 4 degrees C. After storage, hot dogs and packages were rinsed with 0.1% peptone water. Diluent was spiral plated on modified oxford agar and tryptic soy agar and incubated to obtain counts (CFU per package). L. monocytogenes counts on hot dogs packaged in films coated with 156.3 IU/ml nisin decreased slightly (approximately 0.5-log reduction) through day 15 of refrigerated storage but was statistically the same (P > 0.05) as hot dogs packaged in films without nisin after 60 d of storage. Packaging films coated with a cellulose-based solution containing 10,000 and 7,500 IU/ml nisin significantly decreased (P < 0.05) L. monocytogenes populations on the surface of hot dogs by greater than 2 log CFU per package throughout the 60-d study. Similar results were observed for hot dogs packaged in films coated with 2,500 IU/ml nisin; however, L. monocytogenes populations were observed to be approximately 4 log CFU per package after 60 d of refrigerated storage from plate counts on tryptic soy and modified oxford agars.

Escherichia coli O157:H7 emerged as a foodborne pathogen in 1982 and can cause three major disease syndromes (hemorrhagic colitis, hemolytic uremic syndrome, and thrombotic thrombocytopenic purpura). Outbreaks caused by E. coli O157:H7 have been linked to ground beef, milk, apple cider, lettuce, radish and alfalfa sprouts, and water. In 1994, an outbreak of E. coli O157:H7 infection was linked to dry, fermented, pork and beef salami. In response to this first implication of a dry fermented sausage product, the United States Department of Agriculture/Food Safety Inspection Service developed guidelines requiring sausage manufacturers to validate that their processes achieve a five‐log reduction of E. coli O157:H7. Various validation studies have shown that E. coli O157:H7 is able to survive in sausages that are fermented and then dried to various moisture‐to‐protein ratios of 2.3, 1.9, or 1.6:1. Additional thermal processing methods or longer fermentation processes were utilized to achieve 5‐log reductions.

The purpose of this study was to develop and characterize a packaging film coating containing nisin. A spot-on-lawn assay was used to determine the effect of acid type (ascorbic, acetic, hydrochloric, lactic) and nisin level (equal increments from 10,000 IU to 9 IU) to be used in the formulation of the film coating. Zones of inhibition were measured after incubation on tryptic soy agar (37 degrees C, 48 h). Low-density polyethylene films coated with differing levels of nisin were characterized by field emission scanning electron microscopy, tensile strength, elongation, and water vapor transmission rate. The MIC of nisin in solution was 157 mg/ml. All acids were equally inhibitory (P > 0.05), but acetic acid produced the largest zone of inhibition (21 mm). Field emission scanning electron microscopy confirmed that the cloudy appearance of the films was due to sodium chloride found in the commercially prepared nisin. Tensile strength increased as nisin concentration increased, which also corresponded to increasing film thickness. The nisin coatings (10,000 and 2,500 IU/ml) did not have a significant effect (P > 0.05) on the water vapor transmission rate of the low-density polyethylene film.

Low-density polyethylene film was coated with a solution containing a high-molecular-weight or low-molecular-weight methylcellulose and hydroxypropyl methylcellulose. Films contained 10000, 7500, 5000, 2500, or 0 IU/cm 2 nisin. Film samples were placed into peptone water, and 10-L samples were removed and placed onto spiral plated lawns of Listeria monocytogenes. Zones of inhibition were measured using a caliper. Films containing 5000, 7500, and 10000 IU/cm 2 nisin inhibited L. monocytogenes after 30 min; films with 7500 and 10000 IU/cm 2 nisin inhibited L. monocytogenes after 60 min and 8 h, respectively. No zones of inhibition were observed after 24 h and 4 d for all films. After 8 d, zones of inhibition were observed for films with all levels of nisin except 2500 IU/cm 2 . Films with 0 and 2500 IU/ cm 2 nisin did not produce zones of inhibition throughout the study. Molecular weight of the cellulose-based carrier had no effect on inhibition of L. monocytogenes. A standard curve of inhibition was developed using solutions of 10000, 7500, 5000, 2500, or 0 IU/cm 2 nisin applied directly to lawns of L. monocytogenes. The amount of inhibition using a direct application of a solution was 25% to 50% more effective for inhibition of L. monocytogenes compared with the coated film samples. Overall, the coated film samples were effective for inhibition of L. monocytogenes, particularly when 7500 and 10000 IU/cm 2 nisin were used, but the release of nisin was not controlled and did not provide consistent inhibition throughout the 8-d study.

The effectiveness of a typical production process for eliminating Escherichia coli O157:H7 in directly acidified snack sticks made with beef or a venison/beef fat blend was evaluated for formulations of different fat content (10% and 25%) and type of direct acidulant (encapsulated citric or lactic acid). Raw batter inoculated with E. coli O157:H7 to an initial level of approximately 7.1 log CFU/g was stuffed into 21‐mm casings and processed according to a thermal‐processing schedule typical of those used commercially for directly acidified sausage products (maximum internal product temperature of 68.3 °C, followed by drying and cooling). For both beef and venison/beef fat blend snack sticks, log reductions ranged from 6.2 to > 6.6 CFU/g at the end of processing. Although moderate reductions (1.5 to 2.0 log CFU/g) were achieved as a result of processing to internal product temperatures of 68.3 °C, latter stages of the process (during which products were dried and cooled) factored prominently in the overall lethality of the process, and were essential in achieving the 5‐log reduction required by the U.S. Dept. of Agriculture, Food Safety and Inspection Service. The efficacy of the process was not affected (P≤ 0.05) by fat content (10% or 25%) or by the type of direct acidulant used (encapsulated citric or lactic acid). Phenol red sorbitol agar was more effective for recovering heat‐ and acid‐injured E. coli O157 than MacConkey sorbitol agar was and, therefore, provided a more conservative estimate of process lethality.

Midwestern meat processors were surveyed to determine whether consensus existed among industry processing practices for jerky production. Seventy-eight plants were contacted, 37 responded and 33 plants sent 61 samples consisting of whole muscle (56%) or chopped and formed (44%) jerky. Samples had mean water activity, salt (NaCl) and pH of 0.74, 6. 85% and 5.85, respectively. Plants used either smokehouses (34) or commercial ovens (3). Nine plants measured wet bulb temperature, and one used a relative humidity instrument. However, 35 plants claimed that they were able to control humidity. Controls included closing dampers, steam injection, direct addition of water, placing a pan of water in the house, or a combination of methods. Plants used sodium nitrite (32), sodium erythorbate (15) and potassium sorbate (5), and vacuum (78%), no vacuum (32%) and gas flush (14%) packaging. Most products were stored at room temperature (38%) or refrigerated (32%); or a combination of methods was used.