Low Sodium Neapolitan Pizza Prepared With Seawater: Nutritional Properties, Sensory Characteristics, Metabolic Effects

The aim of the present study is testing the nutritional properties, the sensory characteristics and the metabolic effects of a novel recipe of Neapolitan pizza featuring the substitution of common salt with commercial seawater in such proportion as to reduce the total amount of sodium chloride in the otherwise traditional dough by approximately 50%.

The dough for both StP and SWP will be prepared from 170 g of organic flour (Agguggiaro and Figna 5 stagioni, 80% type 00/20% type 1, Curatolo, Padova, Italy) with the addition of 110 mL of tap water or commercial seawater respectively. To the StP 0.05 g of brewer's yeast and 5 g of unrefined salt (Sale Vero, Oro di Sicilia Srl, Nubia di Paceno, Trapani, Italy) will be added, while only 0.02 g of yeast and no salt were added to the SWP. Because salt is known to reduce the fermentation rate, based on the calculation that the amount of sodium chloride in SWP would be approximately one half of the StP content, it was decided to use approximately half the amount of yeast while maintaining constant the fermentation time, which was 15 h for both doughs. Commercial seawater is supplied by Steralmar Srl (Bisceglie, BT, Italia).

The trial is conceived as a double blind balanced randomised crossover trial, where each subject acted as his/her own control by consuming the two different pizzas at one week elapsed time from one another according to a balanced randomised sequence. The trial was approved by the Ethical Committee of the University of Naples Federico II (n. 403.20).

The participants will sign an informed consent to participate and receive detailed written instructions by a trained researcher about the study protocol: avoid any intense physical activity and complete the evening meal by 9 pm on the day before the test; have a standard breakfast (explained in detail) before 8.30 on the morning of the test; drink at least 300 mL of water between breakfast and the meal test, to guarantee normal hydration, not eating between breakfast and the meal test to guarantee a standard hunger level.

Weight, height and blood pressure (BP) will be measured just before the test, systolic and diastolic blood pressure and heart rate will be measured 3 times and the participants will be requested to void just before being weighted and the urines produced thereafter during the 3 h of the test will be collected.

The meals will be consumed in groups of 4 volunteers at a time under standard conditions in the metabolic kitchen at Federico II University Hospital.

The volunteers will be requested to drink 300 mL of water during the meal, which will have a maximum duration of 20 min. An additional volume of 300 mL has to be drunk in the 3 h after the meal. In both meals, at intervals of 30 min for a total of 3 h, a battery of Visual Analogue Scales (VAS) will be administered to assess possible differences in the satiating power of the two pizzas and their sensory characteristics, as described in the dedicated session.

Blood samples will be drawn from an indwelling antecubital venous cannula for the measurement of glucose, insulin and sodium concentration in the fasting state and every 30 min thereafter for 3 h after eating was begun and the Area Under the Curve will be calculated.

The volume of the 3 h urine collection will be measured, and the sodium and creatinine concentrations measured by ISE and by an enzymatic colorimetric method.