Mendes Rogério, Schimmer Ove, Vieira Helena, Pereira João, Teixeira Bárbara
Portuguese Institute for the Sea and Atmosphere (IPMA), Department for the Sea and Marine Resources, Lisbon, Portugal.
Sequid GmbH, Bremen, Germany.
J Sci Food Agric. 2018 Jan;98(1):369-376. doi: 10.1002/jsfa.8480. Epub 2017 Jul 10.
Abusive water addition to octopus has evidenced the need for quick non-destructive methods for product qualification in the industry and control of fresh commercial products in markets. Electric conductivity (EC)/pH and dielectric property measurements were selected to detect water uptake in octopus.
A significant EC decrease was determined after soaking octopus in freshwater for 4 h. EC reflected the water uptake of octopus and the correspondent concentration decrease of available ions in the interstitial fluid. Significant correlations were determined between octopus water uptake, EC (R = -0.940) and moisture/protein (M/P) ratio (R = 0.923) changes. Seasonal and spatial variation in proximate composition did not introduce any uncertainty in EC discrimination of freshwater tampering. Immersion in 5 g L sodium tripolyphosphate (STPP) increased EC to a value similar to control octopus. EC false negatives resulting from the use of additives (STPP and citric acid) were eliminated with the additional determination of pH. Octopus soaked in freshwater, STPP and citric acid can also be clearly discriminated from untreated samples (control) and also from frozen (thawed) ones using the dielectric properties. No significant differences in the dielectric property scores were found between octopus sizes or geographical locations.
Simultaneous EC/pH or dielectric property measurements can be used in a handheld device for non-destructive water addition detection in octopus. M/P ratio can be used as a reference destructive method. © 2017 Society of Chemical Industry.
向章鱼中滥加水已证明行业内需要快速无损的产品鉴定方法以及市场上新鲜商业产品的控制方法。选择电导率（EC）/pH和介电性能测量来检测章鱼中的水分吸收情况。
将章鱼在淡水中浸泡4小时后，确定其电导率显著下降。电导率反映了章鱼的水分吸收情况以及组织液中可用离子相应的浓度降低。确定了章鱼水分吸收、电导率（R = -0.940）和水分/蛋白质（M/P）比（R = 0.923）变化之间存在显著相关性。近似成分的季节性和空间变化在电导率辨别淡水掺假方面未引入任何不确定性。浸泡在5 g/L三聚磷酸钠（STPP）中会使电导率升高至与对照章鱼相似的值。通过额外测定pH消除了因使用添加剂（STPP和柠檬酸）导致的电导率假阴性。使用介电性能也可以清楚地区分浸泡在淡水、STPP和柠檬酸中的章鱼与未处理样品（对照）以及冷冻（解冻）样品。在章鱼大小或地理位置之间未发现介电性能得分有显著差异。
同时进行电导率/ pH或介电性能测量可用于手持设备中对章鱼进行无损加水检测。M/P比可作为参考性的破坏性方法。©2017化学工业协会。
