## 1 Introduction  
Vacuum impregnation (VI) is a food processing technique used to introduce different substances to the porous matrices of plant tissue. It has been commonly used in the enrichment of vegetables and fruits with probiotics and micronutrients [1], texture enhancement [2], modification of the sensory attributes [3] and extension of shelf life by pH reduction [4]. The metabolic consequences of impregnating different substances in plant tissues have not been widely studied, although it is an important factor that can affect the product shelf life. It is important to understand that the introduction of other substances into the plant tissue might affect its metabolism and might change the quality of the vegetable and subsequently affect the shelf life. This could lead to the increase in food waste. According to [PERSON] and [PERSON] [5], along with roots and tubers, fruits and vegetables have the highest wastage rates (1.3 billion tons per year) of any food products due to their perishable nature. One of the most common methods used to prolong the post-harvest shelf life of fruits and vegetables is by storing them at low temperatures. As for leafy vegetables like spinach, the storage at low temperatures might reduce the microbiological deterioration but the sensitive tissue might be vulnerable to chilling injury. The effect of chilling injury can be seen as browning, surface pitting, wilting and loss of flavor [6] and, thus, might affect the consumer acceptability and resulted in the increase of post-harvest loss. Most research has been done to treat chilling injury and most research has been focusing on treating and improving the physical appearance of the leafy vegetables. However,to the best of our knowledge, none of the research has explored the effectiveness of GABA, sucrose and SA compounds scientifically reported to mitigate the chilling injury effect. Salicylic acid (SA), a type of phenolic compounds, is widely distributed in plants and is considered as a plant hormone because of its roles in plant growth and development, as well as in responses to environmentally stressful conditions [7; 8; 9]. In recent years, a few studies have reported the effects of SA on chilling injury in fruits and vegetables, such as increasing antioxidant enzyme activities in banana [10], enhancing total antioxidant activity and preserving bioactive compounds in orange fruit [11], improving proline content in banana [12], delaying activities of polyphenol oxidase (PPO) in banana [10] and reducing electrolyte leakage in banana and orange fruit [10; 11]. \(\gamma\)-aminobutyric acid (GABA), a non-protein amino acid, is regarded as an endogenous signal molecule that plays a pivotal role in regulating the stress response and plant growth and development [13]. In plants, GABA content is typically low, but abiotic stresses such as chilling, heat, drought, UV irradiation and low level of oxygen can cause GABA to accumulate rapidly [14; 15]. Recent studies have reported that GABA could be used as a post-harvest treatment to alleviate chilling injury in zucchini [16] and white clover [17] by enhancing proline accumulation and also delays senescence in cherry [18] and blueberry [19] by enhancing antioxidant system activity. Sucrose represents the major transport form of photosynthetically assimilated carbohydrates and plays an important role in plants [20]. Sugars as sources of carbon skeleton are necessary to maintain energy supply and extend the post-harvest life of perishable fruits and vegetables [20]. It has been proven that exogenous sucrose supply can delay senescence in asparagus [21], reduce yellowing and enhance antioxidant capacity of broccoli [22] and reduce nitrate content in baby spinach leaves [23].