Unique Distribution of Diacyl-, Alkylacyl-, and Alkenylacyl-Phosphatidylcholine Species Visualized in Pork Chop Tissues by Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging

Hirofumi Enomoto; Tomohiro Furukawa; Shiro Takeda; Hajime Hatta; Nobuhiro Zaima

doi:10.3390/foods9020205

Unique Distribution of Diacyl-, Alkylacyl-, and Alkenylacyl-Phosphatidylcholine Species Visualized in Pork Chop Tissues by Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging

Foods. 2020 Feb 16;9(2):205. doi: 10.3390/foods9020205.

Authors

Hirofumi Enomoto^{1

2

3}, Tomohiro Furukawa¹, Shiro Takeda⁴, Hajime Hatta⁵, Nobuhiro Zaima^{6

7}

Affiliations

¹ Department of Biosciences, Faculty of Science and Engineering, Teikyo University, Utsunomiya 320-8551, Japan.
² Division of Integrated Science and Engineering, Graduate School of Science and Engineering, Teikyo University, Utsunomiya 320-8551, Japan.
³ Advanced Instrumental Analysis Center, Teikyo University, Utsunomiya 320-8551, Japan.
⁴ Department of Animal Science and Biotechnology, School of Veterinary Medicine, Azabu University, Sagamihara 252-5201, Japan.
⁵ Department of Food and Nutrition, Faculty of Home Economics, Kyoto Women's University, Kyoto 605-8501, Japan.
⁶ Department of Applied Biological Chemistry, Graduate School of Agriculture, Kindai University, Nara 631-8505, Japan.
⁷ Agricultural Technology and Innovation Research Institute, Kindai University, Nara 631-8505, Japan.

Abstract

Phosphatidylcholine (PC) is the major phospholipid in meat and influences meat qualities, such as healthiness. PC is classified into three groups based on the bond at the sn-1 position: Diacyl, alkylacyl, and alkenylacyl. To investigate their composition and distribution in pork tissues, including longissimus thoracis et lumborum (loin) spinalis muscles, intermuscular fat, and transparent tissues, we performed matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI). Eleven diacyl-, seven alkylacyl-, and six alkenylacyl-PCs were identified using liquid chromatography (LC)-tandem MS (MS/MS) analysis. Despite many alkylacyl- and alkenylacyl-PC species sharing identical m/z values, we were able to visualize these PC species using MALDI-MSI. Diacyl- and alkylacyl- and/or alkenylacyl-PC species showed unique distribution patterns in the tissues, suggesting that their distribution patterns were dependent on their fatty acid compositions. PCs are a major dietary source of choline in meat, and the amount was significantly higher in the muscle tissues. Consumption of choline mitigates age-related memory decline and neurodegenerative diseases; therefore, the consumption of pork muscle tissues could help to mitigate these diseases. These results support the use of MALDI-MSI analysis for assessing the association between PC species and the quality parameters of meat.

Keywords: lipid distribution; liquid chromatography-tandem mass spectrometry (LC-MS/MS); mass spectrometry imaging (MSI); matrix-assisted laser desorption/ionization (MALDI); phosphatidylcholines; pork.