**2.3. Sample extraction procedures**

Ten grams of fresh frozen fruits from different production systems was pestled for 2 min with 50 mL of 50% methanol at 25°C using a Polytron blender (Brinkmann Instruments, Westbury, NY, USA). The mixture was filtered firstly through Whatman no. 1 filter paper and then through a 0.45-μm Acrodisc syringe filters (Gelman Sciences, Ann Arbor, MI, USA). The filtrate was finally kept at −20°C, and the extracts resulting from this step were used in the TPC and TAC analysis [24].

### **2.4. Chemicals**

The chemicals used for TPC, TAC, HPLC and ORAC are shown in **Table 1**.


**Table 1.** The chemicals used for TPC, TAC, HPLC and ORAC.

### **2.5. Soluble solids content, titratable acidity and firmness**

Five strawberries were selected randomly and blended thoroughly using a Supreme Juicerator (Acme Juicer Manufacturing Co., New Hartford, CT, USA), and the SSC of the juice was measured at room temperature with a refractometer (Abbe Mark II, Reichert-Jung, Depew, NY, USA) as described previously [25]. TA was measured by diluting 1 mL of strawberry juice with 9 mL of distilled water, adjusted to pH 8.1 using 0.1 N of NaOH (Accumet AB15 Basic pH metre; Fisher Scientific) as described previously [25]. Firmness was ranked from 1 (very soft) to 5 (very firm).

### **2.6. Fruit postharvest quality**

Five fruits per replicate randomly selected from each plot were placed on Whatman no. 1 filter paper in open Petri dishes and left at room temperature (23°C) to evaluate postharvest deterioration. Fruit weight loss and juice leakage, fruit glossiness and the postharvest incidence of grey mould (*Botrytis cinerea* Pers.) were monitored daily until the fruits were considered non marketable. Fruit weight loss was calculated according to Wang et al. [26] using the following method:

$$\text{Weight loss = weight}\_{\text{day} \, x} \text{ -- weight}\_{\text{day} \, x+1} . \tag{1}$$

where weightday *<sup>x</sup>* is the total weight of the five tested berries in each Petri dish and weightday *x*+1 is the total weight of the same five berries day after.

The fruit juice leakage was ranked from 1 ('no leak or juice loss') to 4 ('significant fruit leak or juice loss'), fruit glossiness was ranked from 1 ('dull') to 3 ('shiny'), and presences of grey mould were ranked from 1 ('no disease') to 5 ('the presence of mould') [24].
