created different models

lib/models/ingredient.dart

@@ -0,0 +1,16 @@
+import '../src/enums.dart' show IngredientType;
+import 'unit.dart';
+
+class Ingredient {
+  final String title;
+  final List<Unit> possibleUnits;
+  final List<String> preferredBrands;
+  final IngredientType type;
+
+  Ingredient({
+    required this.title,
+    required this.type,
+    this.possibleUnits = const [],
+    this.preferredBrands = const [],
+  });
+}