Tirloni Erica, Stella Simone, Bernardi Cristian, Moretti Vittorio Maria, Bersani Carla, Cattaneo Patrizia
Department of Health, Animal Science and Food Safety, University of Milan , Milan, Italy.
Ital J Food Saf. 2016 Nov 17;5(4):6165. doi: 10.4081/ijfs.2016.6165. eCollection 2016 Sep 20.
This study aimed to evaluate the shelf life of sliced cooked liver packaged in MAP (70-85% N, 15-30% CO) and stored in refrigeration (4°C) or slight thermal abuse (8°C) for up to 49 days (declared best before date 45 days). The proximate composition, aw nitrites and NaCl content were determined at T0. Weekly, samples were submitted to microbiological [total viable count (TVC), lactic acid bacteria (LAB), spp., coagulase positive staphylococci, sulphite reducing clostridia, yeasts and moulds, and spp.] and physicalchemical analyses [pH, colorimetric parameters, total volatile basic nitrogen (TVBN), thiobarbituric acid reactive substances (TBARs)], in parallel with consumer acceptability tests. The product characteristics (low salt and nitrites concentration, high aw and pH close to 6.5) were not efficient hurdles for microbial growth. No pathogens were detected in the samples; the initial TVC [5.4 Log colony forming unit (CFU)/g] increased rapidly, reaching values around 8 Log CFU/g at T14 for both the series, and was almost totally composed by LAB, leading to the acidification of the product (pH at T49=5.05 at 4°C and 5.24 at 8°C). The other microbiological parameters were below 2 Log CFU/g. The product showed a good protein and lipid stability (TVBN <33 N/100 g and TBARs <8 nmol/g at T49). The sensorial quality of liver was more affected by the storage time than by the temperature. An evident colour modification was detected after T35, when the product was also frequently rejected by the panellists, mainly due to odour. Thus, the shelf life of sliced cooked liver should be shortened below 30 days.
本研究旨在评估包装在气调包装（70 - 85%氮气，15 - 30%二氧化碳）中的切片熟肝在冷藏（4°C）或轻度热滥用（8°C）条件下长达49天（宣称保质期45天）的货架期。在T0时测定其近似成分、水分活度、亚硝酸盐和氯化钠含量。每周将样品进行微生物学分析[总活菌数（TVC）、乳酸菌（LAB）、 菌属、凝固酶阳性葡萄球菌、亚硫酸盐还原梭菌、酵母和霉菌以及 菌属]和物理化学分析[pH值、比色参数、总挥发性碱性氮（TVBN）、硫代巴比妥酸反应性物质（TBARs）]，同时进行消费者可接受性测试。产品特性（低盐和亚硝酸盐浓度、高水分活度和pH值接近6.5）对微生物生长并非有效障碍。样品中未检测到病原体；初始TVC[5.4对数菌落形成单位（CFU）/克]迅速增加，两个系列在T14时均达到约8对数CFU/克的值，且几乎全部由LAB组成，导致产品酸化（4°C时T49的pH值 = 5.05，8°C时为5.24）。其他微生物学参数低于2对数CFU/克。产品显示出良好的蛋白质和脂质稳定性（T49时TVBN < 33 N/100克，TBARs < 8 nmol/克）。肝脏的感官质量受储存时间的影响大于温度。在T35之后检测到明显的颜色变化，此时产品也经常被评审员拒绝，主要原因是气味。因此，切片熟肝的货架期应缩短至30天以下。
