Shelf-stable and safe intermediate-moisture meat products using hurdle technology

Innovative technologies for producing and preserving intermediate moisture foods: A review

Intermediate moisture foods (IMF) or semi-dried foods (SDF) have gained more attention worldwide having features very similar to fresh food products, but with a longer shelf life. This review presents the recent developments in novel technologies and methods for the production and preservation of IMF. These include new drying methods, using agents to reduce water-activity, innovative osmotic dehydration technologies, electro-osmotic dewatering, thermal pasteurization, plasma treatments (PT), high pressure processing (HPP), modified atmosphere packaging (MAP), edible coating, active packaging (and energy efficiency, improve quality and extend the shelf life of the final food AP) and hurdle technologies (HT). Innovative methods applied to producing and preserving IMF can enhance both drying products. Yet more systematic research is still needed to bridge knowledge gaps, in particular on inactivation kinetics and mechanisms related to thermal and non-thermal pasteurization technologies for control of pathogens and spoilage micro-organisms in IMF.

Development of shelf-stable, ready-to-eat (RTE) shrimps ( Litopenaeus vannamei ) using water activity lowering agent by response surface methodology

Three water-activity-lowering agents (composite phosphate, sorbitol and glycerol) were used to develop a kind of shelf-stable, ready-to-eat (RTE) shrimp. Formula of water-activity- lowering agents was optimized by response surface methodology (RSM) using a central composite design. Model equation was proposed with regard to the contents of composite phosphate (X1), sorbitol (X 2) and glycerol (X3) : [Formula: see text]. The model with a very low probability value (P < 0.0003) was highly significant and the value of lack-of-fit was 0.4028, indicating that the model could predict water activity of shrimps using different agents. Composite phosphate of 0.22%, sorbitol of 3.12% and glycerol of 2.51% were found to be the optimal condition to obtain the lowest water activity of 0.884. Compared to the control shrimps, RTE shrimps treated with water-activity-lowering agents had a longer shelflife and higher sensorial acceptability. During storage at temperature of 35 °C, the quality of RTE shrimps in term of appearance, flavor and texture was found to be superior to the untreated ones. Texture profile, TBARS value, contents of astaxanthin and free amino acid of treated samples were found to be decreased slower from origin value compared to that of untreated samples. These RTE shrimps were biologically safe and sensorially acceptable after 30 days of storage at temperature of 35 °C. Briefly, the application of water-activity-lowering agents extent the shelflife of RTE shrimps obviously and would be beneficial for the exploitation of white shrimp.

Use of γ-irradiation to reduce high levels of Staphylococcus aureus on casein–whey protein coated moist beef biltong

Moist beef biltong strips (mean moisture content = 53.6%, NaCl content = 1.91% and a(w) = 0.979) was inoculated with Staphylococcus aureus ATCC 9441 (10(6)-10(7) cfu/g), or sprayed with distilled water (non-inoculated controls). Both non-inoculated and inoculated biltong strips were coated with a casein-whey protein (1:1) edible coating followed by irradiation to a target dose of 4 kGy. S. aureus, aerobic plate, yeast and mould counts were performed to determine the effect of gamma-irradiation and the edible coating on inoculated S. aureus and the spoilage flora of the biltong. Moisture and NaCl content, a(w) and pH measurements were also performed. None of the intrinsic properties were affected to a practically significant extent. Irradiation reduced all microbial counts (P < 0.05), i.e. inoculated S. aureus (6 log cycles), aerobic plate count (5-6 log cycles) and yeast and mould counts (1-2 log cycles). Irradiation at 4 kGy is thus effective to ensure safety of moist beef biltong, and provided that initial fungal counts are not excessive, may extend the shelf-life. The edible coating had no significant effect (P > 0.05) on microbial counts, possibly because the high moisture content of the biltong diminished its oxygen barrier properties.

Effect of gamma irradiation on the survival of pathogens in kwamegi, a traditional Korean semidried seafood

Kwamegi (semidried raw Pacific saury) is traditional seafood available in Korea. It has water activity in the range of 0.90 to 0.95. Spoilage and the growth of most pathogenic bacteria is retarded because of low water activity, low temperature, and packaging. However, it is contaminated with bacteria of public health significance and poses a hazard to the consumer because it is consumed raw without any cooking. The effectiveness of these hurdles in preventing the growth of Staphylococcus aureus, Bacillus cereus, Salmonella Typhimurium, and Escherichia coli and the efficacy of irradiation treatment in eliminating these bacteria from kwamegi using inoculated pack studies was examined. Radiation sensitivity of S. aureus, B. cereus, Salmonella Typhimurium, and E. coli in kwamegi was investigated. D10-values of these organisms in kwamegi were 590 +/- 13.6, 640 +/- 14.9, 560 +/- 45.4, and 550 +/- 8.6 Gy, respectively. The growth of all four test organisms inoculated into these foods during 4 weeks of storage at an ambient winter temperature (ranging from -5 degrees C to +5 degrees C) was recorded. All four pathogens (inoculated at 10(6) CFU/g) were eliminated by irradiation at 4 kGy. These studies unequivocally demonstrate that irradiation, with a combination of low water activity and low temperature, results in microbiologically safe kwamegi.