How did slavery affect the culture and values of the white population of the south?
The above answer is incorrect in several respects. Barbecue was not a slave invention; it was learned by the Spanish from the Indians. They called it "baracoa," which loosely translated meant meat cooked over hot coals. Fried foods, including chicken, were brought to the south by European immigrants, primarily Germans, who fried foods frequently. The Banjo prowess of slaves is largely legend created by the music of Stephen Collins Foster among others which portrayed slaves as happy and content working on the plantation.
The primary effect on culture and values was in class distinction. Very few southerners owned slaves. Slaves were so expensive that less than one tenth of the population owned at least one slave; fewer than one per cent owned more than ten. Those who did were considered (by others and themselves) as the leaders of society. They were typically the magistrates, legislators, senators, and similar political and community leaders. Those at the top of the social pyramid often went into serious debt to present an image of affluence which did not always exist. They believed that as the leaders of society, they must demonstrate their leadership through some degree of largesse. So there was a certain facade created by social expectation that would not exist had slavery not existed; as the ownership of slaves translated directly into an indication of wealth.
Even non-slaveholding whites were supporters of the institution. Many aspired to be slaveholders themselves one day; and the existence of slavery meant that there was always one classification below them on the social scale. So one of the important effects of slavery was to clearly define social standing for both races.
I cannot agree what white slave owners used slave women "openly" for sexual purposes. There were many instances of abuse, of course; but it was not a routine matter by any means. Many slaveholders treated their slaves with some degree of kindness, even though the line between the two was indelibly drawn. In those instances in which a sexual relationship existed between the master and slave, the mistress of the house was normally aware; however it was an unspoken understanding. Open sexual abuse would hold one up to social disgrace and contempt. Ironically, the mistress often vented her rage for this offense on the slave rather than her husband. Many female slaves received cruel treatment at the hands of mistresses as a result of tranferred anger. There were, of course, instances of young men wishing to prove their manhood by attacking slaves sexually; an act which also was held in some disdain by polite society.
It should be noted that slave ownership was relatively uncommon, as slaves were expensive. As a result ownership of slaves, and the number of slaves owned was often had a cultural affect in determining one's status on the Southern social ladder. The upper class were the planters, who by definition owned a minimum of twenty slaves. Less than three per cent of the population qualified. The planters were not only the gentry, they also were the magistrates and members of the legislature. The small group of planters owned over fifty percent of the slave population.
They exercised considerable cultural affect through control over the market for staple crops. An affect on values was they believed that the welfare of the South as a whole was dependent upon their own welfare, their prosperity. Since lesser members of white society aspired to become planters one day, they all tended to agree with the planters' assessment of themselves.
Slaves were at the bottom of the social ladder. Even the poorest whites, who barely survived on subsistence farming, considered themselves better than the most comfortable slave. Slavery thus became the defining factor in determining the culture and values of white society in the antebellum South.
The impact of slavery on white culture is easy to see. It had a huge impact on white material culture. To give two examples, we can see African slaves bringing such things as barbecue and fried chicken to Southern white food culture and we can see Africans introducing things like the banjo to Southern musical culture.
The impact on values is harder to nail down with certainty. Many scholars argue that slavery coarsened Southern values. It made Southerners (they say) more accepting of things like violence. It also made the South a more patriarchal society because it created a system in which the slaveowners were able to openly use slave women sexually while the wives of the owners had to simply accept their behavior. These effects are, of course, much harder to prove than the effects of slavery on Southern culture.