As a child he was puzzled that she had separate plates for some foods and used chicken fat instead of pork fat when cooking meals.
Years later, as an adult, he found out why, and embarked on the long path to converting to Judaism.
"I like to say that I discovered my faith through pots and pans," the 60-year-old chef said as he stood in the kitchen of the modest synagogue in Palma on the island of Majorca where he prepares kosher meals for the local Jewish community.
"Curiosity about my grandmother's habits in the kitchen turned into interest in the religion, this interest turned into love and this love turned into faith."
Forced to adopt Catholic faith
Pina belongs to the island community of Chuetas, the descendants of Majorcan Jews who were forced to convert to Christianity in the 14th and 15th centuries and kept Jewish traditions alive in secret at great personal risk.
The Chuetas – whose name comes from the Catalan word for pig – number an estimated 20,000 of the islands' 860,000 residents.
Like other descendants of Jews forced to convert elsewhere in Spain and other nations, the Chuetas generally have been reluctant to identify themselves as Jews, a legacy of the secrecy and fear passed down over generations.
But encouraged by an atmosphere of greater religious tolerance and aided by Shavei Israel, a private Jerusalem-based organization, a small minority of Chuetas like Pina are rediscovering and reaffirming their Jewish roots.
Since 2010 Pina, who sports a cross-cropped white beard and wears a kippah, has attended classes on Judaism organized by the group as part of his bid to formally convert to the religion.
About ten Chuetas have already converted to Judaism, according to Shavei Israel, which helps the descendants of Jews who converted in Spain and other countries return to the religion.
Dozens more have attended lessons in Hebrew and Jewish history, culture and religion taught by Shavei Israel to learn more about their background even if they have no plans to convert at the moment.
"I feel we the Jewish people have a historical and moral responsibility to the Chuetas and we have the opportunity now to help those who want to return to Judaism," said Shavei Israel founder and chairman, Michael Freund.
"The best revenge for what the Inquisition did to the Jews of Palma is to help as many descendants of Chuetas to return to the faith."
Shunned by Catholics and Jews alike
Most Chuetas bear surnames of 15 families whose ancestors were executed as heretics by the clerical authority known as the Spanish Inquisition. The names have made it easy to identify them – and discriminate against them.
They have historically been shunned by Majorca's Catholic majority as well as its tiny, mostly expatriate Jewish community.
"We have suffered a great deal," said Pina, who recalls being bullied in school for being a Chueta.
But in July Rabbi Nissim Karelitz, the head of a religious court in the Israeli city of Bnei Brak, officially recognized the Chuetas as Jewish after years of campaigning by Shavei Israel.
The ruling does not automatically confirm the Jewish status of every member of the community.
Chuetas who want to make a return to Judaism will still have to be vetted by a rabbinical court that will examine their family histories to determine whether they are Jewish. But the ruling makes the process easier.
"After years during which Jews did not consider us to be one of them, and the goys saw us as Jews, this decision is a real recognition," said Miquel Segura, a Chueta writer who converted to Judaism in a 2009 ceremony in New York at the age of 67.
"It is an arrival at safe port because we were castaways from two shores and it was very sad."
Unlike other descendants of Jews who were forced to convert in other parts of the world, many Chuetas can prove their Jewish lineage back hundreds of years because of the longtime refusal of Catholics in Majorca to marry them.
Pina traced his family tree all the way back to the year 1500 with the help of his genealogist brother and he hopes this will strengthen his request to convert to Judaism.
"There have been times where I have asked myself if all of this is worth it," said Pina, who has lost several friendships due to his decision to convert.
"In the end reason prevailed. My roots are Jewish."