ABSTRACT
Quality attributes were evaluated for irradiated (0, 1.8, or 2.6 kGy) frankfurters formulated with 0% or 3% potassium lactate/sodium diacetate solution and stored aerobically or vacuum packaged at 4 degrees C for 4 or 8 wk, respectively. Quality analyses included descriptive sensory panel, pH, L*a*b* color values, and TBARS determination. Aroma and flavor quality were retained for aerobically stored frankfurters with lactate/diacetate throughout shelf-life. Meaty/brothy complex aroma and flavor, smoke aroma and aftertaste, spice aroma and flavor, astringency, sourness, bitterness, springiness, cohesiveness, and juiciness attributes were lower for aerobically stored frankfurters formulated without lactate/diacetate compared to those with lactate/diacetate toward the end of storage. Sensory color and other quality attributes were minimally influenced by either treatment. Addition of lactate/diacetate and irradiation were also effective shelf-life extenders for vacuum-packaged frankfurters. There were fewer influences on sensory characteristics for vacuum-packaged frankfurters compared to those that were aerobically packaged. However, small yet significant differences were detected by sensory panelists for some aroma and flavor attributes, which remained consistent between treatments throughout storage. Sensory and instrumental color scores varied slightly, but were fairly consistent throughout vacuum-packaged storage. Overall, lactate/diacetate retarded deterioration of frankfurters throughout aerobic storage and helped maintain quality with or without irradiation for vacuum-packaged frankfurters.
Subject(s)
Food Irradiation , Food Packaging/methods , Food Preservation/methods , Food Preservatives/pharmacology , Meat Products/standards , Taste , Animals , Consumer Behavior , Humans , Lactates/pharmacology , Odorants/analysis , Pigmentation , Sodium Acetate/pharmacology , Temperature , Time FactorsABSTRACT
The use of antimicrobial ingredients in combination with irradiation is an effective antilisterial intervention strategy for ready-to-eat meat products. Microbial safety was evaluated for frankfurters formulated with 0% or 3% added potassium lactate/sodium diacetate solution and inoculated with Listeria monocytogenes before or after treatment with irradiation (0, 1.8, or 2.6 kGy). Frankfurters were stored aerobically or vacuum packaged and L. monocytogenes counts and APCs were determined while refrigerated. The incorporation of lactate/diacetate with or without irradiation had a strong listeriostatic effect for aerobically stored frankfurters. Outgrowth was suppressed and counts were not different from initial counts (5.2 log CFU/frank compared with 5.0 log CFU/frank); however, those without the additive increased steadily (5.4 to 9.3 log CFU/frank). Irradiation treatments alone had higher L. monocytogenes counts after 3 wk. For vacuum-packaged frankfurters, both the addition of lactate/diacetate and irradiation were effective at controlling growth after 8 wk. Large and incremental reductions in total counts were seen for irradiation treatments. Initial counts were reduced by 3 log CFU with the application of 1.8 kGy while 2.6 kGy decreased counts over 5 log CFU. These reductions were maintained throughout storage for lactate/diacetate-treated frankfurters. By 8 wk, L. monocytogenes counts on 1.8 and 2.6 kGy irradiated frankfurters without lactate/diacetate increased to 7.43 and 6.13 log CFU, respectively. Overall, lactate/diacetate retarded the outgrowth of L. monocytogenes on frankfurters throughout aerobic storage and the combination of irradiation and 3% lactate/diacetate reduced and retarded growth of L. monocytogenes, especially during the last 2 wk of vacuum-packaged storage.
Subject(s)
Anti-Bacterial Agents/pharmacology , Food Contamination/analysis , Food Irradiation/methods , Food Preservation/methods , Listeria monocytogenes , Meat Products/microbiology , Colony Count, Microbial , Consumer Product Safety , Dose-Response Relationship, Drug , Dose-Response Relationship, Radiation , Food Handling/methods , Food Microbiology , Food Packaging/methods , Lactates/pharmacology , Listeria monocytogenes/drug effects , Listeria monocytogenes/growth & development , Listeria monocytogenes/radiation effects , Sodium Acetate/pharmacology , Time Factors , VacuumABSTRACT
We have examined the nuclear genes encoding the small subunit of ribulose-1,5-bisphosphate (RuBP) carboxylase from soybean. One member of this gene family, designated SRS1, has been isolated from a soybean DNA library constructed in the lambda vector Charon 4A. The complete nucleotide sequence and structure of this gene including its two introns and portions of the 5' and 3' flanking sequences were determined. The first exon encodes the entire transit peptide (55 amino acids) and the first 2 amino acids of the mature sequence. Based on analysis of the nucleotide sequence, we concluded that the precursor of the soybean small subunit consists of 178 amino acids. A gene-specific probe for SRS1 was used to show that this gene is transcribed and that steady-state levels of its transcript are strongly light regulated. S1 nuclease mapping was used to locate the potential start of transcription in the sequence and showed that the small subunit gene contains a cap site, TATA box, and -80 sequence, which match the consensus animal sequences. The mature SRS1 small subunit polypeptide of 123 amino acids contains 30 and 34 amino acid replacements relative to the previously determined amino acid sequences from pea and spinach, respectively. Southern blotting of restriction digests of soybean nuclear DNA and data on the complete structure of SRS1 suggest that a multigene family of at least 10 members encodes the RuBP carboxylase small subunit in soybean. Quantitative evolutionary comparison of the soybean small subunit sequence for SRS1 and the pea small subunit sequence suggests that these two genes diverged long before the divergence of pea and soybean.
