cultures-ways.js

const names = cultures.map(item => item.cultureName)
// ['Soybean', 'Maize', 'Wheat']

const energies = cultures
  .reduce((acc, nextObject) => {
    const nextValue = nextObject.energy.quantity;
    const currentValue = acc[nextObject.energy.unit] 
      ? acc[nextObject.energy.unit].quantity 
      : 0;
    acc[nextObject.energy.unit] = {
      quantity: currentValue + nextValue,
    };
    return acc;
  }, {})
// { kJ: { quantity: 1728 }, g: { quantity: 0 } }

const totalQuantity = cultures
  .filter(item => item.quantity)
  .reduce((acc, nextObject) => acc + nextObject['quantity'], 0);
// 2700.80