public class Product
     {
         public string Name { get; set; }
         public DateTime Expiry { get; set; }
         public string[] Sizes { get; set; }
     }

    Product product = new Product();
    product.Name = "Apple";
    product.Expiry = , , );
    product.Sizes = new string[] { "Small" };
    string json = JsonConvert.SerializeObject(product);
    Product result = JsonConvert.DeserializeObject<Product>(json);

     public class Product
     {
         [JsonProperty("Name")]
         public string ProName { get; set; }
         [JsonProperty("Expiry")]
         public DateTime ProExpiry { get; set; }
         public string[] Sizes { get; set; }
     }

     string json = "{\"Name\":\"Apple\",\"Expiry\":\"2008-12-28T00:00:00\",\"Sizes\":[\"Small\"]}";
     var product = JsonConvert.DeserializeObject<Product>(json);
     var result = JsonConvert.SerializeObject(product);