How to add new relationship in spring data neo4j 4.1.2 - spring

Question

I already followed this Tutorial.
I want to add new ingredient called Beef to the Meat category that already created by following tutorial above. Here is my code to add new ingredient :
Category categoryMeat = categoryRepository.findByName("Meat");
Ingredient ingredientBeef = ingredientRepository.findByName("Beef");
ingredientBeef.setCategory(categoryMeat);
ingredientRepository.save(ingredientBeef);
Then I pair beef with carrot:
Pairing pairingNew = new Pairing();
pairingNew.setFirst(ingredientBeef);
pairingNew.setSecond(carrot);
pairingNew.setAffinity("Delicious");
pairingRepository.save(pairingNew);
Then I remove the beef using this code :
Ingredient deletedBeef = ingredientRepository.findByName("Beef");
ingredientRepository.delete(deletedBeef);
Then I try to add new ingredient using this code and pair lamb with carrot:
Category newCategoryMeat = categoryRepository.findByName("Meat");
Ingredient ingredientLamb = new Ingredient("Lamb");
ingredientLamb.setCategory(newCategoryMeat);
ingredientRepository.save(ingredientLamb);
Pairing pairingNewLamb = new Pairing();
pairingNewLamb.setFirst(ingredientLamb);
pairingNewLamb.setSecond(carrot);
pairingNewLamb.setAffinity("Delicious");
pairingRepository.save(pairingNewLamb);
When I try to save new ingredient lamb, I get this error:
Error executing Cypher "Neo.ClientError.Statement.EntityNotFound"; Code: Neo.ClientError.Statement.EntityNotFound; Description: Relationship with id 6
How to fix it?
For your information: i'm using spring data neo4j 4.1.2 and neo4j community edition 3.0.6
Here's my pom dependency:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-elasticsearch</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-neo4j</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
</dependency>
</dependencies>