Growth Inhibitory and Selective Pressure Effects of Sodium Diacetate on the Spoilage Microbiota of Frankfurters Stored at 4 °C and 12 °C in Vacuum

Abstract

This study evaluated microbial growth in commercial frankfurters formulated with 1.8% sodium lactate (SL) singly or combined with 0.25% sodium diacetate (SDA), vacuum-packaged (VP) and stored at 4 °C and 12 °C. Standard frankfurters without SDA, containing 0.15% SL, served as controls (CN). Lactic acid bacteria (LAB) were the exclusive spoilers in all treatments at both storage temperatures. However, compared to the CN and SL treatments, SL + SDA delayed growth of LAB by an average of 5.1 and 3.1 log units, and 3.0 and 2.0 log units, respectively, after 30 and 60 days at 4 °C. On day 90, the SL + SDA frankfurters were unspoiled whereas the SL and CN frankfurters had spoiled on day 60 and day 30 to 60, respectively. At 12 °C, LAB growth was similar in all treatments after day 15, but strong defects developed in the CN and SL frankfurters only. Differential spoilage patterns were associated with a major reversal of the LAB biota from gas- and slime-producing Leuconostoc mesenteroides and Leuconostoc carnosum in the CN and SL frankfurters to Lactobacillus sakei/curvatus in the SL + SDA frankfurters. Thus, SL + SDA extends the retail shelf life of VP frankfurters by delaying total LAB growth and selecting for lactobacilli with a milder cured meat spoilage potential than leuconostocs, particularly under refrigeration.

Assessment of the Spoilage Microbiota and the Growth Potential of Listeria monocytogenes in Minced Free-Range Chicken Meat Stored at 4 °C in Vacuum: Comparison with the Spoilage Community of Resultant Retail Modified Atmosphere Packaged Products

“…fuchuensis from Lb. sakei and its closest relative species Latilactobacillus curvatus [35,37]. In agreement, the remaining four (MC6, MC9, MC33, MC73) arginine-negative Latilactobacillus isolates failed to ferment D-xylose, as well as melibiose and L-arabinose, while they grew well in 6.5% and 8.0% salt and fermented maltose (Table 3).…”

“…Presumptive LAB (TSAYE or MRS) isolates were confirmed for Gram-positive and catalase-negative reactions by the rapid 3% KOH and 3% H 2 O 2 testing methods, respectively, and then, they were grouped according to basic taxonomic criteria at the genus or species level [34,35]. Unless stated otherwise, the incubation temperature was 25 • C for all biochemical tests.…”

“…Unless stated otherwise, the incubation temperature was 25 • C for all biochemical tests. Grouping of the LAB isolates was based on cell morphology by phase contrast microscopy, growth at 37 • C and 45 • C in MRS or BHI broth, gas (CO 2 ) production from glucose, ammonia (NH 3 ) production from arginine, growth in the presence of 6.5, 8.0, and 10.0% NaCl, slime formation from sucrose, acetoin production from glucose, and fermentation of 13 key differentiating sugars (Merck or Serva), L arabinose, cellobiose, galactose, lactose, maltose, mannitol, melibiose, raffinose, ribose, sorbitol, sucrose, trehalose, and xylose, in 96-well miniplates [32,35]. One to five representative colonies of each LAB group (i.e., depending on the group size) were tested for hydrogen sulfide (H 2 S) formation on lead acetate (LA) agar with 0.1% (v/v) Tween 80 and 0.005% (w/v) MnSO 4 4H 2 O, incubated aerobically and anaerobically (BD Gas Pack EZ Anaerobe Container System, Becton Dickinson Co., Sparks, MD, USA) for 5 days [32].…”

“…MA, microscopic appearance as rods (R), curved rods (CR), slender rods (SR), coccobacilli (CB) or cocci (C); CO 2 , gas production from glucose; NH 3 , ammonia production from arginine; 37 Based on the biochemical identification results (Table 3), 50 (65.8%) of the 76 LAB isolates from all spoiled VP chicken meat minces belonged to the major phenotypic group A (Table 4) of Latilactobacillus sakei [35,37]. All were facultative heterofermentative lactobacilli which grew at 37 • C but not at 45 • C, produced ammonia from arginine, and fermented galactose, sucrose, and trehalose, but failed to ferment xylose (Table 3), mannitol, raffinose, and sorbitol [34,35]. According to Tsafrakidou et al [32], the MCM (group A) isolates of Lb.…”

Pectinase Activities of Selected Fungi Grown on Agrowastes via Solid-state Fermentation

“…Pectinases have also been recovered using acetate buffer [41,42]. However, some studies have reported acetate as a preservative and its effect in the suppression or considerable reduction of gene expression in particular enzymes, such as alcohol dehydrogenase [43][44][45][46][47]. Hence, its exclusion from this investigation.…”